Help!! Insight, knowledge, and tips needed for this...

[Dilweed]

Quote, originally posted by joatmon »my guess would be powertrain control module, sometimes referred to as the ECU, which is perhaps electronic control unit. The car's computer that controls how the engine runs, and when an automatic tranny shifts. You can reset it by diconnecting the negative lead on the battery for a while, some say 2 minutes, others say 15. Ahhh, I was thinking along the lines of "resetting" something, notably disconnecting the battery, but I wasn't sure how to do it. So, what do I do? Can you please tell me how to do this? Thanks!

[4azdmunky]

Yes you are correct, I guess it is called EUC in the vibe and PCM in Saturns. Sorry it took so long to respond, I'm in Georgia visiting my wifes family.

[4azdmunky]

Just unhook the neg battery cable, let it sit for at least 20 minutes (over night if you have the time), clean it while its off, might was well add water to the battery too if you dont have a sealed battery. Use distilled or filtered water.hook it back up, restart the car.Dont rev the engine, just let car idle for 10 minutes.Take it out for a spin. It can take up to 2 weeks for the car to settle down all the way. You should see the most improvement by day 3. At least that seems to be the average.

[Dilweed]

Quote, originally posted by 4azdmunky »Just unhook the neg battery cable, let it sit for at least 20 minutes (over night if you have the time), clean it while its off, might was well add water to the battery too if you dont have a sealed battery. Use distilled or filtered water.hook it back up, restart the car.Dont rev the engine, just let car idle for 10 minutes.Take it out for a spin. It can take up to 2 weeks for the car to settle down all the way. You should see the most improvement by day 3. At least that seems to be the average.Done. Just did that last night. The car had the battery disconnected for over 3 hours, then it idled for ten minutes, then a 25 minute spin down some longer back roads. Gas needle seems to still be sinking fast (part of my original complaint), but I will have faith in what you said about three days to a couple of weeks' time for the car to settle. Thanks, munky! ** Received a compliment from a perfect stranger last night in a parking lot, too! "Pretty car," remarked an older woman. She asked if I like it, and I had to bite my tongue regarding this gas mileage, but elected to admit that, yes, I do like this car. Heh. I really, really hope that the mileage adjusts and gets up to the claims that I'm seeing everywhere in this online community!*Crossing fingers*

[ColonelPanic]

You may want to (if you haven't already) start logging every single tank in the event you need this information as ammo later... Hopefully it improves for you soon!

[4azdmunky]

Dilweed..Any updates on this issue?

[Dilweed]

Quote, originally posted by 4azdmunky »Dilweed..Any updates on this issue?I did what you suggested, and I managed 30 mpg all highway. It's been almost two weeks since I reset stuff by disconnecting the battery. Still terrible in the city, though. About 20 mpg, and that needle drops every time I start it up. Waiting it out is the best I can do while I look for someone to trade 16" alloys for my huge 17" alloys.Keep the ideas coming!

[patrickogrady]

Trade 16s for 17s? How many miles on your tires? Mine are brand new...PEI Canada here...

[Dilweed]

They seem like new, really. 9K miles. They're monsters!

[mikey00]

Your mileage problem is being caused by the 17" wheel/tire tire situation. You have 17" wheels on a base with a speedo calibrated for 16". You never mentioned the tire size but I bet they are oversized which is adding to the problem. 1oldbanjo posted a simple test for checking the odometer above but I never saw your response. I would do this first before chasing all these other probable causes. I bet you find your odometer is off by quite a bit and your car is actually traveling more miles than the odometer is showing. Do your calculations once you know these numbers. I bet your mpg is not as bad as you think it is. I would definetly try to trade out the 17" wheel/tire combo. Somebody with stock 16" will trade you to get the 17" look. Changing to 16" is not going to improve your actual mpg. It will just make the odometer accurate to reflect the true miles traveled with will give you the true mpg.Mike

[Dilweed]

Thanks, Mike. My door has the sticker with the 17" tire settings already on it, though. The previous owner must have optioned up through the factory. Each mile traveled seems accurate. I wish you were spot on, but I think it's set this way through the factory. What do you think?

[mikey00]

I thought I was on to something here because I didn't think 17" wheels were on option on the 05 base. I have an 05 base myself and still have a brochure. I just checked it and 17" actually were an option on the base.As long as your odometer is checking out accurate, my theory is blown away. If this is the case, I would be inclined to stick with the 17" wheels/tires and just shop for a good all weather 17" tire in the proper size. If you changed to 16" wheels/tires your speedometer and odometer would now be off in the other direction. With the snow you get in Maine you may even consider a set of dedicated winter tires but then you have the additional cost and hassle of seasonal tire changes. Check out tirerack.com to get an idea of what is available and an education on tire types.Another thought is to go to 16" wheels/tires so you save some money on tires and see what the dealer would charge to calibrate your speedometer for the 16" tires. On cable driven speedometers it is usually a small plastic gear in the trans that drives the speedometer that has to be changed. I am not sure how they do it on the Vibe.

[CAN-AWD-VIBE]

Quote, originally posted by mikey00 »As long as your odometer is checking out accurate, my theory is blown away. If this is the case, I would be inclined to stick with the 17" wheels/tires and just shop for a good all weather 17" tire in the proper size. If you changed to 16" wheels/tires your speedometer and odometer would now be off in the other direction. With the snow you get in Maine you may even consider a set of dedicated winter tires but then you have the additional cost and hassle of seasonal tire changes. Check out tirerack.com to get an idea of what is available and an education on tire types.Another thought is to go to 16" wheels/tires so you save some money on tires and see what the dealer would charge to calibrate your speedometer for the 16" tires. On cable driven speedometers it is usually a small plastic gear in the trans that drives the speedometer that has to be changed. I am not sure how they do it on the Vibe.no need to recalibrate if you get the right size tire 15,16,17,18,19 all fit without calibration if you get the right tire size to go with it. I would be tempted to try a P205/55R16 just to see if they didn't get it right from factory, just to see if it may be out?

[mikey00]

Yes, you are correct. I just wasn't thinking along those lines when I posted my reply. I am not sure if this is how they do it on the Vibe but as long as you use a 16" or 17" tire size so that the circumference remains the same the speedo is not affected. There are online tire calculators to figure this out.I am not sure why you suggest trying 16" tires just to see if they got it right from the factory. If the Vibe uses the above method to keep the speedo accurate it shouldn't matter. Even if the Vibe doesn't use that method dilweed checked out the odometer and said each mile seems right on. So I don't think thats it.Mike

[2002sportside]

What size tires are actually on the car?

[Dilweed]

Quote, originally posted by 2002sportside »What size tires are actually on the car? 215 50 r17's

[mikey00]

215 50 r17's are also the size listed in the 05 Vibe brochure I have. If I put that size into a tire calculator and compare it to the stock size (205 55 R16), the 17" tires have a circumference of 80 while the 16" tires have a circumference of 78.2. The 17" tires will show a speedometer reading 2.4% slower than the 16" or the odometer will show 2.4% less for distance traveled. I don't know if there are different speedometer calibrations for these 2 tire sizes or if they just decided it was close enough.The price difference for good winter or all season tires is about $20 more per tire for 17" compared to the 16". I would stick with the 17" and just get a good set of tires.But I guess the original thread starting question is still unsolved: Why is your mpg so bad?

[Dilweed]

Quote, originally posted by mikey00 »215 50 r17's are also the size listed in the 05 Vibe brochure I have. If I put that size into a tire calculator and compare it to the stock size (205 55 R16), the 17" tires have a circumference of 80 while the 16" tires have a circumference of 78.2.The options for 16's are many, though, and 17's aren't so variable for me - and all of which are quite expensive. Plus, I heard from several sources that a tire with less width is better in the snow. What is the width difference between the 55 r16's and the 50 r17's? Would that really make much of a difference?Thanks for all of your insight, by the way.

[mikey00]

The 17" are 3/10" wider than the 16". I can't imagine that there would be much difference in snow assuming both are good rated all season or winter tires. If you are more of a "practical" guy trade out the 17" for some 16". You will save some money on tires over the life of the car. I am sure someone will want the 17" look over the practability. Maybe even consider a set of steelies with wheel covers. It will increase your trade possibilities. However if you like the 17" look, just order a good set of tires and stick with it. tirerack.com is a good place to research your tires, no matter where you buy them. What tires are presently on the car. You may want to check them out at tirerack and see how they are rated for snow.

[4azdmunky]

Alignment?How is the tread wear?I guess it is possible to have your tires mounted backwards (outside sidewall is facing inside), but I think this is grasping at straws.Do you have a stuck injector? Do you have access to a ODBII reader like this: http://www.scantool.netCould the O2 sensor be going out causing the car to run rich? or the engine coolant temp sensor? I had one go out on my Saturn and it caused the timing to go ff so bad that the car wouldn't start. Not bad for a $7 part.What does the inside your exhaust tip look like? is it blackened? If so, your running rich (too much gas).Does anyone know if there is a way to test the ECU? could it be corrupted from the factory?

[4azdmunky]

What type of oil are you using?i noticed a improvement by switching to Royal Purple. I also switched the transmission fluid to Royal Purple. It runs so much smoother that my wife made a comment and she doesnt know that I switched fluids.

[4azdmunky]

I was wondering if the O2 was going out but not out enough to throw codes.Check the plugs, that's a good idea. They would show how rich/lean the engine is running.So the tires could (while being a long shot) an issue. I remember my jeep in HS (1991) was setup this way and it had all sorts of weird 'issues' from loss of gas mileage, to vibrations, to sluggish feeling.

[Dilweed]

Hey, Munky -No codes were triggered by anything, and that's why the dealership service department couldn't do anything about this. Just wait it out is all they could prescribe. Meh. I changed the oil a couple weeks ago to Castrol gtx, which was great with my neon. No complaints there. I re-set the ecu by disconnecting the negative battery, as stated earlier. Been using the car all highway this past week, and actually got almost 32 mpg, but... city driving consisting of short trips at 25-40 mph still KILLS my mpg. Nowhere near 29 mpg; more like 20, and this is on the base model.The tailpipe does have dark color at the tip....COuld that be from taking it out on back roads and flooring it for a few seconds at a time in order to "open it up" and clean out the possible carbon in the guts of this vehicle from the previous owner?Seems to shift smoother now, anyway. I dunno. What should I say if I bring it back to the dealer for a road test? Should I mention the running rich possibility?Oh, and the tread wear was really messed up when I brought it to get a rotation on a hunch. 3 different readings on all 4 wheels!

[4azdmunky]

Castrol is good oil, haven't heard anyone having issues with it.A little dark at the tip could be normal, depending on the quality of the gas. If the inside is coated, then there is a problem.Having your own OBDII tool is a good idea, because you can watch things like real time voltage on your sensors as well as things like how much air pressure your MAF is reporting, you can data map your fuel use (trim) and perform your own dyno's.If your tires are worn weird, that is something to look into. It doesn't mean that your alignment is currently off, but if they were worn from a previous bad alignment, then they will affect your current good alignment and ride. I am going through this right now on my 92 S10. I rebuilt the front end this summer, piece by piece. During the rebuild, I wore the outside of my front right tire down. Now that the truck is fixed, and the alignment is fixed, the worn tire bounces and pulls like a belt slipped inside of it....I wonder if there is a slight vacuum leak? Do you hear a light high pitch whine when the hood is up?I fixed a VW Jetta this week at work that belongs to an employee that was running like crap and had poor gas mileage. The dealer said it was normal, but as soon as I found and plugged the vacuum leak, the car has ran 100% better.

[Dilweed]

Quote, originally posted by 4azdmunky »I wonder if there is a slight vacuum leak? Do you hear a light high pitch whine when the hood is up?I fixed a VW Jetta this week at work that belongs to an employee that was running like crap and had poor gas mileage. The dealer said it was normal, but as soon as I found and plugged the vacuum leak, the car has ran 100% better.I couldn't tell you, but there is a high pitched humming noise when I get above 59-60 mph....

[4azdmunky]

No, you would hear the vacuum leak at idle with the hood up. You'll know it if you find it.Something we do with classic VW engines to find leaks is to spray around the carb, the base of the carb, the manifold, and the manifold end(s) with carb cleaner. If the engine changes pitch or idle when spraying these area's then there is a air leak. The same might work for this. I would spray around the throttle body and the PCV hoses under the right side of the engine cover. I know some old school VDubers that use propane to instead of carb cleaner. Never had an explosion or a fire. Just dont set the can on the battery and cross the + and -.

[Dilweed]

I filled up at the usual gas station (Shell, which has been steady, at least) a couple days ago and then drove it all highway at about 65-70 mph. Down to below 3/4 of a tank, and guess how many miles it's logged? 78!! That's freaking TERRIBLE! On a bad tank, i'd get at least 100 miles at the 3/4 mark. I am seriously disappointed in this vehicle. I am beside myself, and I feel like losing money and ponying up for a Toyota Corolla here. Add to this the very strange tread wear on the tires (dealer said to just keep rotating them every 6k miles...) and my very limited options (All very expensive, too) with my 17" alloy rims, and you can see what I mean. I cannot believe that people are getting such high figures for CITY driving mpg, let alone highway.... I am 100% disappointed and completely frustrated. Just idling this thing for two minutes while waiting in a parking lot LOWERED the gas needle in front of my eyes! There went a good 30 highway miles or so just in idle.What the heck is going on?? It's going back to the dealer, and I'll have them road-test it until they see what I'm seeing. Sorry, all... I am having a moment, and it's really frustrating. Grrrrrrr....I wish there was a magic solution. I can't afford any more payments on a different car, but, geez... this Vibe is such a let down every time I start the damn thing up. I will be lucky to get 225 miles out of this tank.Thanks for bearing with me, too. I'm all ears for other advice or tips, as always. Any mechanics out there with some ideas and magic words to say to the techs at the dealership that would get them interested in troubleshooting more seriously over this problem? That would also be much appreciated.I shouldn't be lamenting the loss of my old Neon, for goodness's sake...

[ragingfish]

My 03 base never got better then about 27 in mixed driving loops.It may be time to see a different dealer. And realize you're pretty much already driving a Corolla now...

[mikey00]

Here is what I would do if it were my car. First get some good accurate measurements over a few full tanks. No dealer will take you seriously when you base your gas mileage on less than a one tank and looking at the gauge. Maybe even pick up a scangauge. (www.scangauge.com) I realize you may already have more accurate measurements from your previous posts. If after this your mileage is off and your dealer is not helping, try a Toyota dealer. As ragingfish said you are really driving a Corolla here. They have much more experience with the engine. However, with out a lot of good accurate measurements most dealers will tend to blow you off. They would rather work on a car with a CEL.

[Dilweed]

What is a CEL?I brought the car in to the dealer yesterday, and no conclusive results. Everything looks good to them, and no vacuum leaks, etc. He looked me in the eye and said that if I can get 300 miles out of one tank, then that is good -- REALLY good. As if! This guy is full of it, as you can tell. My latest: half a tank (what's that, 6.7 gallons or so?) and 160 miles, all but 20 of those miles are highway driving. So, I got nowhere. THey did a road test for the tires, and they come out to specs for 17" wheels on this vehicle. I'd also called a toyota service guy who's really good and this was months ago. Tried that. He said he couldn't touch it because it's not a Toyota vehicle, even though the main engine components (not all of them, but most of them) are, indeed, Toyota in the Vibe. Grrrrrrrr....General question: why on Earth does the gas needle sink so fast (in a matter of minutes!) when the Vibe idles in a parking lot??Anyway, happy Thanksgiving, everyone! That's a general great thing to celebrate, my weird Vibe fuel economy aside!

[mikey00]

CEL is a Check Engine Light, which allows them to read a code with a code scanner which should point to the problem.As I said before I would not appraoch service people with data based on my last 1/2 tank of gas and how fast the guage is moving. If I were the service manager my response would be the same as theirs. Get some good data based on a number of tanks over some time. I would still approach this through a Toyota tech unless, of course, you are looking for warranty work. Just cause one shot you down doesn't mean they all will.

[Dilweed]

Actually two different Pontiac techs shot me down in the past few months, and the Toyota tech couldn't really help, although he was very informative and helpful with what he could offer for suggestions. I have been figuring the mileage since I bought the car in late July of this year, so I brought that information with me. Nothing the techs can do in the service departments, I guess. It's a royal bummer....

[mikey00]

I do have one other thought. You could try your luck over at matrixowners.com. First do a search on gas mileage or mpg and see if you come up with anything. If not, try joining and posting you question.

[Dilweed]

Quote, originally posted by mikey00 »I do have one other thought. You could try your luck over at matrixowners.com. First do a search on gas mileage or mpg and see if you come up with anything. If not, try joining and posting you question.Thanks, I will check out that site.

[jimincalif]

I just did a 1300 mile trip to N California and back, almost all on I-5 at 75-80 mph. My 03 GT got 32 mpg this trip. When around town I do very little highway driving and consistently get 24 mpg - and I am a bit of a leadfoot.Calculating mileage tank by tank can be misleading, as gas pumps click off at different times. Sometimes I can get almost 2 full gallons in after it clicks, other times just 1/2 gal. Keep a running total of your distance and gas purchases over several fillups to minimize pump error. Ignore the gauge when figuring mileage.

[Moonstone06Vibe]

Poor gas mileage, and strange treadwear patterns? Could the alignment be off? That could have an effect on gas mileage, especially if there's excessive toe-in or toe-out. I don't know what the symptoms of incorrect toe are on a Vibe, but when I experienced it with another car, the symptoms were scalloping of the front tires across the entire tread ( unlike camber / caster issues, where scalloping generally shows up only on the edges) and non-linear responses to steering input from dead center at highway speeds (i.e., you move the steering wheel a little bit off-center, and the car doesn't react at first, so you turn the wheel a little more, and the car responds by changing direction more than you'd expect). My 06 base Vibe needed an alignment from day one; it pulled to the left on a level road at highway speeds. Car now has 9800 miles, and consistently averages 30 mpg on a 90 mile per day commute, 60 miles of which is highway driving ( if you can consider the Long Island Expressway a highway during rush hour).