Does your engine sound exactly like this when cold(read post first)?

montreal · Post by **montreal** » Wed Apr 20, 2005 1:47 am

Quote, originally posted by MiVibe-ToolGuy Â»If you feel up to it hopefully it does not come down to you fixing the car yourself, I have a portable Smoke Machine we used to make the larger DaimlerChrysler machine. I can certainly loan it to you if you think it will help. I just tested it and it is full of smoke. The shipping back to me may be expensive though, the unit is about two feet tall and one foot wide. Weighs about 15-20 lbs. You will need an air supply and it runs off 12 Volts. You are most generous to make me this offer.Major problem is bringing anything across the border and back is very complicated.Now suppose there is an air leak and I don't have access to a smoke machine.Apart from the propane solution, there is also the method of taking rubber tubing and making a stethoscope and listening for a hissing sound. Then there is the idea of disconnecting the vacuum hose at the throttle body and inserting a valve and vacuum gauge in series. The motor could then be run and the vacuum builds up to its maximum. Then the valve is closed trapping the vacuum in the hoses. The motor is stopped and the gauge is monitored to see if the vacuum slowly collapses. If the vacuum holds, then there are no cracks in the hoses.That leaves us with the possibility that there is a leak in the intake manifold gasket. By examining the color of each sparkplug, we may see if there is one much lighter than the others. That would indicate that the air leak is near that cylinder.If smoke can be introduced into the throttle body (via a hose) under pressure without harming the engine components, then I imagine pure air can also be introduced. If we place some soapsuds around the manifold gasket, maybe we will see bubbles.

joatmon · Post by **joatmon** » Wed Apr 20, 2005 1:55 am

Maybe you can work out some deal for the michigan mega meet. I'm sure tool guy wouldn't gloat about "smokin' a matrix"

montreal · Post by **montreal** » Wed Apr 20, 2005 2:22 am

Quote, originally posted by joatmon Â»Maybe you can work out some deal for the Michigan mega meet. I'm sure tool guy wouldn't gloat about "smokin' a matrix" Better idea than blowing soap bubbles off the manifold.Soon I will be doing a compilation of the 5 polls located at the different sites.Tell me if you voted on a poll located on the other site(s) so that I don't count you more than once. So far, it looks like there are about 4 of us with the problem out of a total of 76 who voted.If we assume that the membership is equally distributed between cold and warm climates, then it would appear that 1 in 20 cars might have this problem.The fact that all the attempts by different mechanics to fix all the cars mentioned in the posts makes me think that there is no single engine part that we can be call defective. I canÃ¢Â€Â™t stop thinking that there is an oversight in the computer software, but since the car is 100% drivable and the scantools show no out of line data, it may be hard to claim that there is a defect here.On the other hand, there is definitely a very unpleasant cosmetic issue here that is bound to affect resell value.

ToolGuy · Post by **ToolGuy** » Wed Apr 20, 2005 2:41 am

Quote, originally posted by joatmon Â»Maybe you can work out some deal for the michigan mega meet. I'm sure tool guy wouldn't gloat about "smokin' a matrix" Hey that is true, the work something out part at the Mich meet...Joatman, it is all "Smoke and Mirrors!!!!!!"

joatmon · Post by **joatmon** » Wed Apr 20, 2005 5:59 am

Quote, originally posted by montreal Â»Tell me if you voted on a poll located on the other site(s) so that I don't count you more than once. So far, it looks like there are about 4 of us with the problem out of a total of 76 who voted.If we assume that the membership is equally distributed between cold and warm climates, then it would appear that 1 in 20 cars might have this problem.You and I are the only two who voted yes here at genvibe, and I did not vote in any of your other polls at whatever sites they were on.I think that extrapolating the 1 in 20 poll results to the entire collection of Vibes and Matrixes ever made is a big stretch. You could also look at the same data and say that out of large sampling (five automotive forums worth of people) you only found four people who had had the problem. Not that big of a deal, the GT/XRS clutch issues is much more prevalent. We've had more people with power windows spontaneously shatter than have this cold idle problem. I won't even talk about paint issues.I'm not trying to be discouraging, just realistic. Lucky for me I appear to be the only Viber who has run into this problem. So for Vibes, it seems like its just "one", not "1 in 20".

montreal · Post by **montreal** » Wed Apr 20, 2005 6:34 am

Quote, originally posted by joatmon Â»You and I are the only two who voted yes here at genvibe, and I did not vote in any of your other polls at whatever sites they were on.I think that extrapolating the 1 in 20 poll results to the entire collection of Vibes and Matrixes ever made is a big stretch. You could also look at the same data and say that out of large sampling (five automotive forums worth of people) you only found four people who had had the problem. Not that big of a deal...I agree that its hard to extrapolate the results from 75 votes. People who have problems or who are more preceptive of problems tend to join forums, so for everyone of the 70 who voted no, there are probably thousands more like them, and very few like us.Which is not necessarily a bad thing. The rarer our problem is, the stronger our claim that we stand a more difficult, if not impossible, job of reselling our car without being forced to discount for this cosmetic issue.I say cosmetic issue, because the jury is still out as to whether there is a defective part at the origin of the noise.If ever we could prove that there is a defective part, then we would already have the remedy.

MadBill · Post by **MadBill** » Wed Apr 20, 2005 9:35 am

I really don't think an air leak could be so consistently time/temperature dependent. Has anyone taken data with a Tech II scan tool? It also could be used to record a number of values during the erratic idle period. It might be set up for example to monitor and record RPM, TPS, coolant temp, MAF values, O2 sensor voltage and injector pulse width. It can be triggered when the problem begins and should capture enough data to see what anomaly is responsible. E.g., a spike in the MAF signal preceeds the sudden RPM drop, or the coolant sensor reading jumps 100 degrees, etc..

Mavrik · Post by **Mavrik** » Wed Apr 20, 2005 9:38 am

I'm still trying to wrap my mind around how warranty work ends at $400 if the problem is not fixed... and nothing is done about it after that because the tech is to dumbassed (sorry) to know what else could be wrong.

montreal · Post by **montreal** » Wed Apr 20, 2005 10:06 pm

Quote, originally posted by MadBill Â»I really don't think an air leak could be so consistently time/temperature dependent. Has anyone taken data with a Tech II scan tool? It also could be used to record a number of values during the erratic idle period. It might be set up for example to monitor and record RPM, TPS, coolant temp, MAF values, O2 sensor voltage and injector pulse width. It can be triggered when the problem begins and should capture enough data to see what anomaly is responsible. E.g., a spike in the MAF signal precedes the sudden RPM drop, or the coolant sensor reading jumps 100 degrees, etc..Yes, I witnessed two such tests and supposedly the dealership made a third one at an inopportune time when the car is reported to have not made this noise.The problem is that all the PIDs looked normal during the event.I agree that an air leak should not create this precisely controlled and consistently time and temperature dependent event.Therefore it is likely that the ECU has ordered an unreasonably high cold idle rpm of 2300 instead of the typical 1800 that occurs on cars that don't make this sound. Also the sudden drop of the rpms seems consistent with the way most computers deal with an over-rev situation.Over-rev is defined as an unacceptable high rpm for a given temperature and a given amount of fuel being injected. I believe this strategy is designed to protect the motor if a mechanical part in the drive train should break and there is a sudden loss of load that causes the motor to speed up faster than would be expected for the amount of fuel being consumed. If we can get the initial high rpm to be lowered to a normal 1800, then I think the problem of the over-rev cut-off (which is what creates the pulsing sound) will disappear.So what would explain the computer wanting to order a faster rpm during the initial 2 minutes when the engine is cold? In open loop mode, a typical computer uses all information that is available to help it propose the optimum idle speed.We know that by resetting the computer memory, the computer will propose a lower 1800 rpms in spite of it having the same sensor information available as existed before the memory reset. The act of resetting the memory forces the computer to treat historical and current sensor information in a different way, at least for 2 days until it relearns itÃ¢Â€Â™s bad habit.All this should suggest that the current and historical sensor data on my car is not the same as on other similar cars that don't idle as high.So we are back to the original question, what current and historical sensor data can make the computer decide that a faster rpm is the way to go?Can a small air leak alter the historical data?And can an engine with all its parts being in spec still create this noise?Thanks for your post.

montreal · Post by **montreal** » Wed Apr 20, 2005 10:22 pm

Quote, originally posted by Mavrik Â»I'm still trying to wrap my mind around how warranty work ends at $400 if the problem is not fixed... and nothing is done about it after that because the tech is to dumbassed (sorry) to know what else could be wrong.The lesson that I have learned and that is an important one for all car owners is that when you have a car that is drivable, does not pollute, gets good fuel economy, and has all the scan tests find no defective engine component, then despite the presence of this highly embarrassing noise, the manufacturer may have the right to walk away from the problem.It is at that point that the car owner must assume the burden of proving:1) that even this cosmetic situation diminishes the resale vale of the car, and therefore the owner is worthy of compensation.2) that also there may be a defect in the car that causes this cosmetic issue.By setting up this poll and 4 others like it, I believe that I have proved that even if this issue is merely cosmetic, there has been a diminished value to my car due to the unrepairable noise.I am not confident that there is any scan tool in the world that will prove one way or another whether there is a hidden defect in the motor that causes this noise.In short, just because there is smoke, it may not be possible to prove that there is fire.

joatmon · Post by **joatmon** » Thu Apr 21, 2005 2:58 am

somebody else here just voted yes, who was it?

montreal · Post by **montreal** » Thu Apr 21, 2005 4:45 am

Quote, originally posted by joatmon Â»somebody else here just voted yes, who was it?I don't know, when I set up the poll I selected the option that would not allow anyone, including myself, to know who voted and how.I noticed the new count this morning, so it was in the last 12 hours or so.

montreal · Post by **montreal** » Sat Apr 23, 2005 3:11 am

I have placed the combined results of all polls on different forums at the top of the first post in this thread.It appears that no more than 8% have this issue.

martinz · Post by **martinz** » Wed Dec 07, 2005 4:15 am

I just started a new thread about this because I had missed this one in my searches. I just bought a used 2003 Vibe and am having exactly the same problem. When I bought that car, the temp wasn;t low enough for me to spot the problem on my test drives. Now that temps have dropped, I am having these sysmptoms each morning. I don't have any warranty on the car, it's at over 100,000km. So, I'm waiting for someone more knowledgable to find a solution. I will try to inspect my air hoses to check for any obvious leaks. Thanks.

joatmon · Post by **joatmon** » Wed Dec 07, 2005 9:02 am

I forgot about this problem, and haven't noticed it yet this cold season, but I finally cleaned out the garage enough to park in there. I used to notice the problem most when scraping frost off the windows, engine running to warm up, but since I don't need to scrape anymore, I haven't left it idling to warm up, so I haven't noticed the probHaven't heard from montreal for a while, he was really pursuing this issue, hopefully he'll come back and let us know if he ever found a solution.

montreal · Post by **montreal** » Wed Dec 07, 2005 11:58 am

Back again after a 7 month time out.This season it has been my car's turn to spend the night in the attached un-heated garage which is still slightly above freezing temperature, so I haven't had the car out in the cold yet. Last winter, my car spent the night outside and my wife's car stayed inside.There are three things that I can report:1) I still think the problem is the result of an oversight in the engine computer software, so without a new release, I don't expect any solution.2) A friend of my wife has a Toyota ECHO with the same problem. This is the first report of an occurance in an engine outside the Matrix/Vibe/Corolla family. Does the ECHO use the same engine software? This ECHO's owner was given a written promise from her dealer that no harm would ever come to the engine due to this behaviour. Our problem is the loss in resale value due to the way that the general public distrusts the engines that make this sound.3) I asked for and received a written acknowledgement from Toyota that this problem exists on my car and that Toyota will procede in the future (years maybe) to look for a solution. I need this letter so that if the day arrives when I have to resell my unfixed car in a private sale (not a trade-in which yields less benefit), only then will I be able to assess the real financial loss due to the noise and sue the manufacturer for this loss.The sample audio recordings were hosted last season by a generous member at another forum. One file was a .MP3 and the other much larger file was a .WAV. It seems that one or the other of these two files was downloaded so often that he went over quota and eventually his ISP cut him off, so the links to these files no longer work. I have the original and if some member in this forum would like to host the .MP3 file (50 kb.), I would be happy to email a copy. Please remember that there can be five forums that offer readers the opportunity to access this file, so please make sure you're comfortable with the resources required.

joatmon · Post by **joatmon** » Wed Dec 07, 2005 12:26 pm

Quote, originally posted by montreal Â»I have the original and if some member in this forum would like to host the .MP3 file (50 kb.), I would be happy to email a copy. Please remember that there can be five forums that offer readers the opportunity to access this file, so please make sure you're comfortable with the resources required.If it's only a 50KB file, you could upload it here with a post. When you create or edit a post, there is a file attachment section, use the browse button to locate the file on your local file system and when you post the info, it will upload the file to the genvibe server. Not sure if other corums could hot link to the uploaded file, but you could refer them to the post where it is. THe file upload has a limit of about one megabyte, and it's one file per post.

montreal · Post by **montreal** » Thu Dec 08, 2005 5:39 am

The audio file is now at the head of a new thread so that I can supply the link to other forums discussing this same issue. My car has restarted to idle hunt.

Baltovibe · Post by **Baltovibe** » Thu Dec 08, 2005 6:00 am

Quote, originally posted by montreal Â»Here is the file.located at http://forums.genvibe.com/zerothread?id=20409

Mavrik · Post by **Mavrik** » Fri Dec 09, 2005 1:12 am

only time my Vibe sounded like that was when I had my MAF sensor problem. It would actually idle fine but but sounded like that when I tried to drive it. Of course I had an engine code for a failed MAF. Are they using a TECH II to monitor air/fuel flow mixtures? It sounds like its not getting enough of one or the other...The wife says her old Vibe sounded just like that but she never looked into it to find out what was wrong. She didn't worry about it I guess.

montreal · Post by **montreal** » Sat Dec 10, 2005 2:44 am

Quote, originally posted by Mavrik Â»It would actually idle fine but but sounded like that when I tried to drive it. ........The wife says her old Vibe sounded just like that but she never looked into it to find out what was wrong. She didn't worry about it I guess.We have the inverse problem, the motor hunts as long as the foot is off the pedal (in neutral, or clutch in), but the engine speed becomes smooth the moment you step on the pedal. Once the computer sees the TPS move, it uses a different part of the software. The engine is no longer in idle mode and the computer no longer considers that the rpms are too high and worthy of being attenuated. Pulsing is the result of temporary attenuation due to two separate software routines competing for control of the motor speed, IMHO.

montreal · Post by **montreal** » Thu Feb 02, 2006 1:32 am

Bump.Anyone new having this problem in 2006?

Andrew-4ce · Post by **Andrew-4ce** » Thu Feb 02, 2006 6:21 am

my car does this... it's a 2003 with 100k I bought this past October... as soon as the temp goes below about -6 C it does it on cold starts. Very annoying. I added to your poll.Andrew

montreal · Post by **montreal** » Thu Feb 02, 2006 8:02 pm

Quote, originally posted by Andrew-4ce Â»my car does this... it's a 2003 with 100k I bought this past October... as soon as the temp goes below about -6 C it does it on cold starts. Very annoying. I added to your poll.AndrewThanks for voting.Since Vibe and Matrix ( mine is a Matrix) share the same engine, last spring I asked a local Pontiac dealership if they had ever dealt with this problem. They said no and suggested that the engine computer software in the Vibe (at least in Canada) was different from the software in Vibes sold in the U.S., and that this difference was designed to help the engine work better in a colder climate.Your response is proof that Canadian sold Vibes are just as vulnerable to this problem.

burkeyro · Post by **burkeyro** » Mon Feb 06, 2006 10:56 am

I have this problem as well - I just figured it was the Computer's way to get the car up to temp. when it is really cold - My 5.0 mustang did the same thing when it was really cold. It's annoying as hell but I just go start the car and go back into the house and wait for it to warm up.

montreal · Post by **montreal** » Tue Oct 10, 2006 4:30 am

Hello again, it's been nearly 8 months since I updated this thread.Normally I would not want to bump it up to the front page until at least November, the month when the weather becomes cold enough to allow old and new members to be reminded that this problem is still there.In late June 2005, I received a committment in writing from the head office of Toyota Canada that they would be "investigating this issue when the cold weather resumes". Well the cold weather of winter 2005/2006 came and went without any news from headoffice.By late summer 2006, I was becoming impatient and I contemplated creating a followup letter to Toyota headoffice asking for some concrete proof that some effort was going into this investigation. I sent a letter to an automobile journalist who writes a weekly column in my local paper. I asked him what questions I should be asking Toyota under the circumstances. He didn't even bother to respond so our issue is either a taboo subject or too frivilous for his consideration.Fortunately, a letter sent last month to the Automobile Protection Association (of Canada) fell on much more sympathetic ears, those of president George Iny.George Iny co-hosts a call in radio show each week on a local AM radio station. He has invited me to call in, perhaps even be a guest. I am preparing for this eventuallity and I am hopeful of getting the audio recording played on the air.I even tried to sneak an e-mail about the pending radio program to the president of Toyota Canada, via the JAMA web site, of which he is also president. My e-mail was read at JAMA, but never an acknowledgement of it having been forwarded.The reason I am setting up this post is that I want to formalize the fact that 8 of us voted YES in the poll attached to this thread.While the poll is anonymous, there are posts in this thread made by 8 owners claiming to have the identical issue.They are as follows in no particular order:Heh!heh '03 location:Ontariojoatmon location:?martinz '03 location: OntarioAndrew-4ce '03 location:Ontarioburkeyro '03 loaction:OhioMontreal '03 (Matrix)location:QuebecDo any of the listed owners want to add any comments about what has happened to their cars in the last 12 months?Did any of you have additional work done above what you already mentioned in your posts in an attempt to correct this issue?Nicknames are nice, but do you think that it would be a good idea for me to build a list of real names of the affected owners so that I can forward this list to the APA. If so, PM me and I'll send you my personal e-mail address.Thanks

ToolGuy · Post by **ToolGuy** » Mon Oct 16, 2006 5:15 am

Montral, did you get on the show?Also, as I read your last post I thought "hey there is a car show called Car Talk on Sat mornings here in the states". It is called Car Talk, click and clack the Tappet brothers.They might be able to help! Here is their site but trust me, calling in is way better. There are too many wanna be mechaincs on the site! I got into it with one joe once and refuse to go back. This was in 2002! http://www.cartalk.com/

montreal · Post by **montreal** » Mon Oct 16, 2006 6:09 am

Quote, originally posted by MiVibe-ToolGuy Â»Montreal, did you get on the show?Also, as I read your last post I thought hey there is a car show called Car Talk on Sat mornings here in the states". It is called Car Talk, click and clack the Tappet brothers.I remember hearing an automotive self help talk show on Saturday morning coming in from Vermont. But the show I am supposed to participate in is located here in Canada. The co-host has been busy and has not scheduled my involvement which he promised me three weeks ago. I wrote him today hoping for a response, as his show is on tonight and I don't want to have our subject broached without them first being able to play the audio recording.As for those arm-chair mechanic Tappet brothers (is that their real names?), I don't expect anyone to accurately diagnose this issue without getting their hands dirty. I've used up all my warranty credits, so I can't personally finance an expedition based on what these experts might suggest.Thanks for your interest and I'll post as soon as anything happens here with the radio show. I've suggested that we wait a few weeks until the weather is cold enough to bring to life this issue in cars where the defect is latent in summer.

ToolGuy · Post by **ToolGuy** » Tue Oct 17, 2006 12:35 am

Quote, originally posted by montreal Â»As for those arm-chair mechanic Tappet brothers (is that their real names?), I don't expect anyone to accurately diagnose this issue without getting their hands dirty. I've used up all my warranty credits, so I can't personally finance an expedition based on what these experts might suggest.Thanks for your interest and I'll post as soon as anything happens here with the radio show. I've suggested that we wait a few weeks until the weather is cold enough to bring to life this issue in cars where the defect is latent in summer.Yep, the Tappet brothers is their last name. Both are mechanics by trade and have worked on all makes and models and years. They are great at diagnosis too. I would try to find a station in your area that carries their show and start calling! They really know cars and get all kinds of callers that know nothing about cars but can describe a noise the car is making and the brothers diagnose it! The arm chair guys are on their site, average joes... I think if you tell them it is surging in the cold weather and tell the RPMs the engine sees while doing this, they should be able to help! I know you have all the info to describe this to them! I just am interested since I have heard this before on cars but am baffled as to what causes this. The last I heard this besides yours was in the summer and older 1980's Mustang on my street was doing it.

ToolGuy · Post by **ToolGuy** » Tue Oct 17, 2006 12:52 am

I just looked for any GM TSBs on this issue and still did not find any...I just remembered . I have a good friend who is a General Motors Master Tech. He is an awesome tech! I got to know him through my Corvette and Corvette sites. I will ask him and post on his site your engine audio sample! Stay tuned!

montreal · Post by **montreal** » Tue Oct 17, 2006 2:34 am

Thanks for your two previous posts.Did that older 1980's Mustang (doing it in summer) have electronic fuel injection? If it didn't ,there may be purely mechanical reasons to explain an idle hunting which repeats indefinetely.In our current case, we are talking about the control loop within the computer being crippled by some mysterious defective mechanical part.I imagine that your friend, the Corvette mechanic, is familiar with modern day engine computers and he might have some ideas.As far as the Cartalk radio program, I'll try e-mailing them the audio recording and see if they are interested.

ToolGuy · Post by **ToolGuy** » Tue Oct 17, 2006 2:58 am

Yep the Mustang was a Fuel Injection car. I heard it and walked to the front room of my house to see what the heck was making those rev noises.I know Paul already looked at my posting on his site but has not replied yet. He has a site called corvettemechanic.com, you need to become a member to even view the site and that is where we talk about Corvettes and all cars. It is run by himself and a few other techs. No BS, just all serious car talk. Paul rarely has no idea on what is wrong with a vehicle but in this case, this will be a good one for him to try and solve! To become a GM master tech you must pass a lot of tests and Paul loves knowledge so that is not an issue for him. Cars, trucks, computers or carburettors, Paul knows them!

montreal · Post by **montreal** » Tue Oct 17, 2006 3:14 am

Quote, originally posted by MiVibe-ToolGuy Â»Paul rarely has no idea on what is wrong with a vehicle but in this case, this will be a good one for him to try and solve! To become a GM master tech you must pass a lot of tests and Paul loves knowledge so that is not an issue for him. Cars, trucks, computers or carburettors, Paul knows them! I owned a number of vehicles in the 70's which used the GM 5.7 liter V8 block(350 cu.in.). I believe this block found its way into some early Corvettes, or maybe it was the bigger brother of the 5.7 block.I have fond memories of pulling apart the Rochester 4 barrel carb to change the jets. Today the technology must be quite different. So any master mechanic who can work on a Corvette engine will rate high in my mind.Given that the 1ZZ-FE engine, which has this idle hunting problem, was jointly developed by both Toyota and GM (perhaps Yamaha was also implicated), your friend may have another reason to want to help out his fellow GM-Vibe owners.Thanks for your continuing support, and I just sent off an email to CarTalk, so maybe there will be news from them to share.

ToolGuy · Post by **ToolGuy** » Tue Oct 17, 2006 4:03 am

Yep the GM small block has been around for many years! Ok here is what he said..."HI there,It would be suggested to check crankshaft position sensor when cold, specifically the hz frequency when cold.See what changes when it gets warm.Is it possible that the clearance between the 2 get tighter, therefore the signal is better??Please keep me posted,"Now the hard part will be you getting access to a scan tool that shows this data. At least it is a starting point... I suppose you just need a cold day now! You could also get a baseline of the sensor now, when the engine is warm and then fianlly when it is cold.

montreal · Post by **montreal** » Tue Oct 17, 2006 5:03 am

Quote, originally posted by MiVibe-ToolGuy Â»Ok here is what he said..."HI there,It would be suggested to check crankshaft position sensor when cold, specifically the hz frequency when cold.See what changes when it gets warm.Is it possible that the clearance between the 2 get tighter, therefore the signal is better??Please keep me posted," Paul seems to be suggesting that the signal from the crankshaft position sensor (which basically sets the control loop timing for the computer) could experience a change in phase and/or duty cycle when cold. Or that the odd pulse from this sensor is being lost and the computer has to propose to itself where the missing pulses should be taking place without really knowing for sure. If this is so, could you please ask Paul how the resetting of the ECU (forcing the factory default long term fuel tables to be reloaded) would make such a defective crankshaft position sensor suddenly work perfectly for two days. Also, if the ECU were missing pulses, it would generate an OBD-II error code, which is not the case here.Without wanting to lead Paul too much away from his intuition, I respectfully suggest he try to explain which false engine sensor readings (MAF, coolant temperature, O2, etc) would lead to the ECU thinking that it is necessary to increase idle speed progressively each day following a reset until the runaway idle speed exceeds a threshold which triggers a repetitive fuel cut/fuel resume cycle.ThanksP.S. Before I retired recently, I spent my career programming control loops in robot computers driven by timing sources just like the crankshaft sensor.

ToolGuy · Post by **ToolGuy** » Tue Oct 17, 2006 5:11 am

Sure, I will ask him! Interesting career you had!

ToolGuy · Post by **ToolGuy** » Thu Oct 19, 2006 8:44 pm

Here is what he said now..."Hi there,Well, thank you for the additional details.Yes, when and if the crankshaft signal drops out, the PCM thinks that the signal has stopped because the engine is stopping. Then, the signal picks up, thus the engine adds fuel again.All the technician has to do is monitor the crankshaft signal with a DC HZ scale to see if its dropping out.Cold is the key, because the cold temps cause the open loop operation, which will NOT monitor the o2 sensor readings until closed loop is reached.As for the 'resetting the ecu', is it possible that the fuel injectors are clogging, creating incorrectly atomized fuel and when you reset the ecu, you are starting the fuel trim enable all over again???OBD2 diagnostics are vague in a Vibe, so you may NOT always get a code, so do NOT use a code as an end all for diagnostics.Allthebest, c4c5"

montreal · Post by **montreal** » Fri Oct 20, 2006 9:43 am

Quote, originally posted by MiVibe-ToolGuy Â»Here is what he said now..."Hi there,Well, thank you for the additional details.Yes, when and if the crankshaft signal drops out, the PCM thinks that the signal has stopped because the engine is stopping. Then, the signal picks up, thus the engine adds fuel again.All the technician has to do is monitor the crankshaft signal with a DC HZ scale to see if its dropping out.Cold is the key, because the cold temps cause the open loop operation, which will NOT monitor the o2 sensor readings until closed loop is reached.Please thank him for his contribution.In the area that I worked in, we always assumed that if a pulse from a shaft sensor went missing, it did not mean that there had been a loss of speed by the apparatus, so we built a contingency into the software for this accident. But with an automobile motor, the computer has to be prepared for the case where an engine is reving at say 2000 rpms in neutral and the driver accidently pops the clutch with the transmission in the wrong gear, thus stalling the engine and bringing the rpms to zero within a fraction of a second. Here the ECU would want to instantaneously cut the fuel injection, even though the ignition key is still on.The loss of even one pulse should have an immediate effect in creating a partial loss of power in an engine already turning over under no load at say 2000 rpms. And then, if the pulses immediately resume, the ECU will have no reason not to restore the fuel which will rapidly raise the rpms.So a pulsing of the idle in tandem with the intermittant loss of pulses from the crankshaft position sensor can be easily be explained by this principle.Now if your friend, the mechanic, could download the audio recording and instead of listening to it, if he could load it into an audio editing utility, then he would see the pattern of the engine noise being modulated. The recording has only 20 seconds of the actual event, but when we look at the full 40 seconds, we see something.I have done this and what we see are, for the most part, perfectly spaced bursts of sound within an envelope, much the way the signal from an AM radio transmitter looks on a scope when there is a test tone being transmitted over the radio.Because the pattern we see is so perfect and the cadence is so regular, I am forced to conclude that there is no way that pulses from the crankshaft position sensor, being lost at random, would generate the final product that I have. I believe that the idle hunting I have is simply the result of a too high idle speed occuring due to a fuel trim problem, where the idle speed surpasses the limits imposed in the de-acceleration algorithm.The de-acceleration algorithm is outlined in the Toyota engine design literature which addresses the way the ECU controls the fuel injectors when you are cruising along at 50 mph going down a hill and take your foot off the gas (TPS goes to idle position). If the rpms of the engine (in gear) are above a certain rpm, then the fuel is cut until the rpms fall below a lower threshold at which point the fuel is restored. Normally if you are in gear going down a hill, with your foot off the gas pedal, then the engine speed, with or without a fuel cut, is determined by the transmission gear. If we are in neutral going down the hill, then the motor is disengaged and assumes its low idle speed (of say 800 rpms). But what if some fault in our fuel injectors was causing a leakage of gas into our cylinders beyond the amount normally required for idling. Would the engine rpms speed up and the computer would be upset by the engine speed going above a certain amount, thereby triggering a fuel cut? I believe the same thing is happening to my cold engine trying to warm up in the winter. But that is just my way of explaining the unexplainable.Quote, originally posted by MiVibe-ToolGuy Â»As for the 'resetting the ecu', is it possible that the fuel injectors are clogging, creating incorrectly atomized fuel and when you reset the ecu, you are starting the fuel trim enable all over again???I agree that if the fuel trim gets out of wack over time for some reason, then the way the engine performs is going to change. I would suggest that the result of introducing incorrectly atomized fuel into a cold engine is a higher than normal idle speed. And if you can explain a high idle, then using the de-acceleration algorithm, you can explain idle pulsing.Now can we explain what might be causing a radical change in long term fuel trims which are used by a cold engine in open loop mode?

NewNeptune · Post by **NewNeptune** » Fri Oct 20, 2006 1:36 pm

Quote Â»The de-acceleration algorithm is outlined in the Toyota engine design literature which addresses the way the ECU controls the fuel injectors when you are cruising along at 50 mph going down a hill and take your foot off the gas (TPS goes to idle position). If the rpms of the engine (in gear) are above a certain rpm, then the fuel is cut until the rpms fall below a lower threshold at which point the fuel is restored.Ah! So this is why when I take my foot off at 40 MPH and the RPMs drop out to 1200 and then surge back up? Bad programming of this piece of code? Could the issues be related?

montreal · Post by **montreal** » Sat Oct 21, 2006 12:04 am

Quote, originally posted by NewNeptune Â»Ah! So this is why when I take my foot off at 40 MPH and the RPMs drop out to 1200 and then surge back up? Bad programming of this piece of code? Could the issues be related?Yes and No.You don't say if you are still in gear when you take your foot off the gas pedal. And you don't say what your rpms would be on your car if you were in idle while sitting still. My idle when sitting still and when my engine is all warmed up is 800 rpm. But yours may be much higher because you have modified your car to do that. You may also have added accessories that load down the engine and require more fuel to maintain your (custom?) programmed idle speed.So if you are going down a hill and take your foot off the gas pedal and shift into neutral, then the engine rpms which are already high will begin to drop because fuel is being cut and when they drop below a certain level, the fuel will be resumed. At the moment the fuel is resumed, depending on the amount of fuel that your (custom) program will call for, then your idle speed will either continue to drop or it will rise as it seeks your normal idle speed. So you might get a surge in the idle speed on your tachometer, but you wouldn't feel it at your wheels because you are in neutral.So if you see a surge on your tach, it probably means that you have modified your ECU program in some way.Now if we take our above example and repeat it, but leave the car in gear, depending on the gear, the slope of the hill, and the speed of the car, it is conceivable in my mind that we could have a situation where we take our foot off the gas and the car begins to slow down on compression due to a fuel cut. When the car and engine together reach that critical speed when the ECU orders the fuel to resume, the engine would receive the amount of fuel normally required to maintain idle at about 800 rpms (our TPS is still closed). This small amount of fuel would normally not result in a drastic increase in power to the engine that would cause our car and engine speed to increase back above the threshold required for a fuel cut.But if the slope of the hill and the gearing were such, it might just happen, a continuous "bucking" of the car. I've heard of cars "bucking" in the winter time on a flat surface because the fuel is so rich when the engine is cold, and the engine is so strong. This usually is the result of a bad TPS signal when the foot is OFF the gas pedal.What kind of hill slope and gear ratio would trigger this unique situation?We would need a combination of hill steepness, transmission gearing, and vehicle speed that with our foot lightly on the gas pedal, we are going downhill with our engine turning over at around 2300 rpm if the temperature is about 80 degrees F. The computer has different thresholds for different temperatures. Ideally, it should be first gear because that will make the "bucking" effect most pronounced.If you then take your foot off the gas, the motor should slow down to 2100 rpms reducing the car speed at the same time. When the fuel kicks in at 2100, the car, with this extra assistance from the injectors having been just turned back on, and the assistance from gravity would combine to speed us up and the rpms might rise back to 2300 at which point the injectors would be cut again.This "bucking" cycle could continue as long as the slope of the hill remained the same. Find the right slope to create 2300 rpms in first gear with little or no gas and see for yourself.Why do we rarely hear about such an event happening. First, this would never happen with automatic transmissions.Next, when we are going down a hill, we usually don't take our foot off the gas pedal if we are happy with the speed of the car or if we want to speed up. And if we do want to slow down on compression, we usually choose a gear that will slow us down, a low gear that sends and keeps the rpms high, high enough that they never fall into that deadband between 2100 and 2300. The deadband numbers are taken from the chart on page 16 from the document titled "ENGINE CONTROLS PART #2 - ECU PROCESS and OUTPUT FUNCTIONS". see link:http://www.autoshop101.com/forms/h25.pdfIronically, these two numbers correspond to the exact same limits of my idle hunting problem.In other words, if there is a time when the ECU orders a certain amount of fuel during a cold idle situation without regard for the amount of rpms that results, and if the resultant rpms rises above the numbers on that chart, will the ECU not react exactly the same way it does when you go down a hill in compression?Afterall, we are talking about a manual transmission. How the the ECU know if the car is moving or not?, in gear or not?, clutch depressed or not? It doesn't, so it behaves the same way in each case. That's my theory to explain the idle hunting.Now to explain what is causing the ECU to order so much fuel at idle when cold.

sylvainber · Post by **sylvainber** » Tue Dec 05, 2006 1:11 am

I have been away from the forums for several months... so here's my .02I have experienced the same idle hunting in cold weather since winter 2005 (the car is an 04). first occurence was at -30F at about 16,000 miles (second winter). It began happening at higher temperatures (-20, -10 and then near zero F) later in the seasoni drive for about 45 seconds to a stop near my house in the morning and the idle starts hunting from 2000 to 2200 RPMS while at the stop. If i start the car and let it idle it tends to stay at 2000 RPMS in cold weather (wihtout hunting)once the engine warms up just enough to drop the idle rpms below 2000, the hunting goes away and the idle rpms gradually drop to the normal 'warm idle' at 800 RPM (the car idles smoothly without any hiccups)this winter, cold weather just arrived on 12/1 and now the idle hunting happens at 25 F.Yesterday, the car threw a steady CEL (after idle hunting after startup, at 25F ). Called the dealer on my way home to schedule an apointment in 3 days (soonest they could fit me in)I was scheduled for an oil change this morning at the dealer and they ran a diagnostic. They told me 'bad O2 sensor'. They will put that in to fix the CEL (they think it will address the idle hunting in cold weather starts... but i have my doubts)My warranty runs out in 5 days... i guess i lucked out on the CEL timing... if not on the CEL itselfmy fuel consumption and warm idle are fine (i get an overall 30 mpg with mostly suburban driving) i will update you with the results of the O2 sensor replacement.Sylvain

montreal · Post by **montreal** » Tue Dec 05, 2006 2:25 am

Quote, originally posted by sylvainber Â»I have experienced the same idle hunting in cold weather since winter 2005 (the car is an 04). first occurence was at -30F at about 16,000 miles (second winter). It began happening at higher temperatures (-20, -10 and then near zero F) later in the season.Because the computer takes time to learn in the Fall, it also takes time to forget in the Spring. Even though the outdoor temperature may suddenly drop, it takes several days of sustained cold to get the computer to change. This would explain why your thresholds change.Quote, originally posted by sylvainber Â»i drive for about 45 seconds to a stop sign near my house in the morning and the idle starts hunting from 2000 to 2200 RPMS while at the stop. If i start the car and let it idle it tends to stay at 2000 RPMS in cold weather (without hunting).In my case, if my car is parked outside and it is cold enough outside, then my hunting will occur within 2 minutes as I let the car idle in a stopped position. This Fall, I have had my car in a unheated attached garage. I also found that my hunting was more likely to occur at the first stop sign than if I rolled the car out of the garage and let it idle there for two minutes Two minutes is a long time if you are not looking at a watch. Now that the outdoor temperature has droped, my garage has become cold enough that the hunting will happen while letting the car idle. I agree that driving your car to the stop sign seems to raise the probability that the hunting threshold would be exceeded. Once it is very cold outside, I believe that this difference between driving to a stop sign versus idling for two minutes in front of your home will disappear.Quote, originally posted by sylvainber Â»Yesterday, the car threw a steady CEL (after idle hunting after startup, at 25F ). Called the dealer on my way home to schedule an apointment in 3 days (soonest they could fit me in)I was scheduled for an oil change this morning at the dealer and they ran a diagnostic. They told me 'bad O2 sensor'. They will put that in to fix the CEL (they think it will address the idle hunting in cold weather starts... but i have my doubts)I know of one other forum member who like you had an O2 sensor CEL and idle hunting. He reports that since his O2 sensor was replaced, his hunting has not returned. There seems to be a casual link between a bad O2 sensor and idle hunting. I believe that the hunting is caused by another problem but is agravated if the O2 sensor is also bad, or slow. When the O2 sensor works well and warms up quickly, it can override the other bad problem, and prevent the hunting.There can be at least three things that can go wrong with an O2 sensor. 1) This sensor may not generate a good reading at any time, or 2) it may work well when heated by the exhaust gases, but if the sensors's internal heater is defective, then it won't work when you start your car when very cold, or 3), the sensor may be fine but the electrical current needed to operate the sensor's internal heater may not be supplied by the ECU module.In my case, my O2 sensor was replaced and the hunting did not go away, so I suspect that my ECU is not supplying the necessary heater circuit electrical current.Quote, originally posted by sylvainber Â»My warranty runs out in 5 days... i guess i lucked out on the CEL timing... if not on the CEL itselfIf your 2004 car was purchased in late '03, you seem to be suggesting that the 36 month bumper to bumper warranty is running out. The motor is guaranteed for 5 years, if I am not mistaken, and the computer, being an anti-pollution device, may be 8 years. I don't think the O2 sensor is guaranteed for more than 3 years.In the event that your problem returns in a few weeks, I suggest that you try to protect yourself now by having your work order for your O2 sensor repair also note the incidence of the idle hunting, which in the end may have no link with the O2 sensor. In other words, prior to your car coming off warranty, you need a document testifying to the presence of the idle hunting. And to do this, you may have to leave your car overnight at the dealership so that in the morning, you can have them witness you starting your car outside in the cold and producing the idle hunting.As your O2 sensor has just been replaced, your car will take several days to start hunting again, if it is destined to, so your warranty will probably be expired before you have a steady sequence of cold nights to allow you to leave your car at the dealorship with a reasonable expectation that it will hunt the following morning.In this case, I would have today's work order register the hunting problem with your committment to demonstrate it to them in the coming week or two, if necessary.One warning, don't leave your keys with the dealorship when you leave your car overnight. When I did so, someone accidentally started my car and that sabotaged the demo. Keep your keys and show up early enough the next day before the morning sun warms up your car too much to void the demo. Good luck and please vote in the poll.

sylvainber · Post by **sylvainber** » Tue Dec 05, 2006 3:17 am

merci pour toute l'information Quote, originally posted by montreal Â»If your 2004 car was purchased in late '03, you seem to be suggesting that the 36 month bumper to bumper warranty is running out. The motor is guaranteed for 5 years, if I am not mistaken, and the computer, being an anti-pollution device, may be 8 years. I don't think the O2 sensor is guaranteed for more than 3 years.the warranty on the vibe in the US is 3/36 . Just in case this morning, i had the work order drafted for the CEL, hunting idle and a growing dashboard rattle. I brought in a bulleted letter outlining all the symptoms, which will be filed with the work order (and is referred to hereinto so i'm planting the stake for future warranty work if needed.ps: i took the poll sylvain

montreal · Post by **montreal** » Tue Dec 05, 2006 3:34 am

Quote, originally posted by sylvainber Â» Just in case this morning, i had the work order drafted for the CEL, hunting idle and a growing dashboard rattle.Sylvain,It looks like you have the situation under control.I look forward to reading about the results in a week or two. Montreal

montreal · Post by **montreal** » Wed Dec 06, 2006 10:30 pm

I AM PLEASED TO ANNOUNCE THAT TOYOTA CANADA TELEPHONED ME TODAY TO ADVISE THAT WHAT THEY CALL A "REPAIR SOLUTION" IS PENDING AND THEY HOPE TO DELIVER IT TO ME BEFORE THE END OF THE YEAR.My dealership has already been advised to expect a communication.This will NOT be a technical service bulletin.I pointed out on the telephone that there have been many attempts to fix this idle hunting by the now 23 car owners with this problem, and that all approaches have failed to date. Toyota's answer is that they have made a serious effort in formulating the new proposed "repair solution" and I should have a reason to trust that it will succeed where traditional approaches by many shop mechanics have failed.Stay tuned...

stoutvibe · Post by **stoutvibe** » Thu Dec 07, 2006 2:53 am

Montreal - just wanted to let you know that I have this same problem in my 04 Vibe base w/manual. It has occured ever since I purchased the car new in 2004, but of course didn't surface until cold weather. This morning it was -2 outside and the idle hunting was especially bad - much much worse than ever before. The rpm was surging up and getting cut back so quickly that the rpms were going above the normal 2300 to 2500-2600 from what seemed like just the momentum from the engine accelerating so violently. It was almost like the computer couldn't keep up with the idle shooting up so quickly. One difference in this incident is the time at which this hunting starteds. As established, it usually takes about a minute to start acting up, which is about normal for mine also. However, this morning as soon as it turned over it just started doing it. I tried shutting down and restarting a few times with no noticeable effect. It is supposed to be just as cold tomorrow here, so I am going to try to get it on video. I already have the normal idle hunting on video and could post if needed for others who still might be confused about what exactly this strange phenomenon is. Thanks for all of your work on this problem and hopefully your efforts will pay off with a true solution to the problem!

montreal · Post by **montreal** » Thu Dec 07, 2006 8:36 am

Quote, originally posted by stoutvibe Â»The rpm was surging up and getting cut back so quickly that the rpms were going above the normal 2300 to 2500-2600 from what seemed like just the momentum from the engine accelerating so violently. My peak idle is never much above 2300, so if your peak idle is hitting 2500-2600, it means your fuel mixture is much richer than mine, which is already abnormally rich.My car takes 60 odd seconds for the idle to build up to 2300 at which time the hunting starts. Because your engine is getting more fuel than mine immediately after turning the key, your hunting starts right away.Hunting is nothing more than a repeated series of fuel cuts. Normally when going down a hill, if you take your foot off the gas when your rpms are already above 2300, your computer will order a fuel cut to place your car under compression. Any situation which results in your engine turning at above 2300 rpms when your foot is off the gas pedal results in the same fuel cut. Your computer with its manual transmission has no idea if your car is sitting still or coasting down a hill. It cuts the fuel in either case.Your challenge is to determine what is causing so much fuel to be injected immediately after starting the car. Pull the fuse on the computer and if the problem goes away for a few days, then that will indicate a different situation compared to the case where the hunting does not temporarily go away.Good luck.P.S. Please vote in the poll.

stoutvibe · Post by **stoutvibe** » Thu Dec 07, 2006 9:00 am

I will try removing the fuse and resetting the ECU and see what that does. Here is a video to my normal idle hunting problem (not the severe case I mentioned):http://www.youtube.com/watch?v=Ev8ZUbN5f8sThanks for your advice.

Neouka · Post by **Neouka** » Thu Dec 07, 2006 9:03 am

mine does the hunting thing too now that it's below 0 out, but not nearly as bad as your sound clip. It'll do it 4-6 times maybe, and each time it takes a little longer before it hits the fuel cut. Personally I don't think it's hurting anything mechanically, so I'm not overly worried about it, really... Mostly it just makes me laugh.But my car has about 7000 km of powertrain warranty left, so maybe if you find a solution I can have it fixed

montreal · Post by **montreal** » Thu Dec 07, 2006 9:45 am

Quote, originally posted by stoutvibe Â»Here is a video to my normal idle hunting problem (not the severe case I mentioned):Viewing your video made me feel like I was in my car.There are a number of reasons that would explain why the number of seconds between each of your pulses is slightly longer than mine - engine and transmission oil viscosity, electrical load, accessories on the V-belt.Your rpm range however is very similar to mine. How long after starting your car did you have to wait for your pulsing to begin? Mine is 60 to 75 seconds.