Rough Idle

1.8-liter VVTL-i (2ZZ-GE) and VVT-i (1ZZ-FE) engine, transmission, exhaust, intake, and performance tuning discussions
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blue_can
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Rough Idle

Post by blue_can »

Wonder if anyone can help me troubleshoot this or experienced something similar that they fixed. I disconnected the battery while replacing the recirc air actuator a while ago. I cannot recall exactly why but I did remove the airbag so it may have been part of the procedure to disable the airbag.

Shortly after the repair when driving and came to a stop the car suddenly got a very rough idle. I assumed this was due to the battery being disconnected so I continued to drive and it got better. But the rough idle never went completely away. It seems to be particularly noticeable just after coming to a stop.

I did some basic things like disconnecting and reconnecting the battery, running injector cleaner and cleaning out the TB. None of this seems to have helped I also used the OBD2 scan tool and looked at the real-time engine parameters and don't see anything clearly wrong.

In some situations the idle rpm seems lower than what it should be. Do these numbers look normal? When warmed up and in "P" the idle reads about 700rpm. It drops to about 660 in "D" and around 640 in "R". I tried shifting through the ranges and on some occasions the values seem to end up lower particularly just after shifting. On one occasion I even saw the rpm drop to around 580 just after going into "R" and then rising to around 620. On another occasion the idle was much higher in "R" just after shifting into it and did not see the dip like on a previous occasion.

Is it possible the issue could be related to the transmission. I could check the line pressure on the transmission and see what that looks like if the rpm variations is based on shifting in and out. It does seems like the idle is also a bit rough when in "P" but I don't have a frame of reference now as to how things used to be and also from what I recall the car always seemed a bit rough at idle. The rough idle feel does get worse as the rpm drops.

Any ideas would be welcome on other things to look at.
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vibrologist
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Re: Rough Idle

Post by vibrologist »

How about the spark plugs? How old are they? how do they look?
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blue_can
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Re: Rough Idle

Post by blue_can »

Good point - did not check the spark plugs and never looked at them. Vehicle is 07 and now has about 71K miles and I thought they were supposed to be changed at 100K so I have yet to take a look at them.
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blue_can
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Re: Rough Idle

Post by blue_can »

Checked the spark plugs today - looked healthy and all gaps within spec. Also checked the PCV valve and that tested fine as well.

I'm starting to wonder if this is an engine/transmission mount issue. I went through the test again and the vibration is really only noticeable in "R" or "D" with "R" being much worse. I had someone sit in the car and shift through the ranges and observed the engine. The idle appears steady in all ranges but when in "D" and especially "R" the engine shakes a fair bit. I've also recently noticed somewhat of a jump when going into "D" or "R" recently which is also a possible clue.

The service manual lists the normal idle range as 650 - 750 so broadly the idle speed is okay although a bit lower than 650 in some cases. However today I did observe that the idle speed was less of a factor and the bigger factor in causing the vibration is whether it was in gear or not. When in "P" or "N" the idle smooths out and also the engine shaking stops.

I did inspect the mounts and don't see any obvious issue. Not really sure how to tell which one(s) might be an issue.
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vibrologist
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Re: Rough Idle

Post by vibrologist »

blue_can:
I am shooting in the dark:

How long has it been that the ATF has been replaced? If the fluid is not so good anymore it could affect the stall speed of the torque converter and induce vibration.

Since you played around with the battery: are the poles really clean and firmly attached? Is there corrosion entering the battery cables? How about having the battery tested? Sometimes a minor thing can cause unexpected issues.

Try tracing back your steps from that repair prior to the vibration issue.

By the way: please edit your signature and add your location and the model you have.
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blue_can
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Re: Rough Idle

Post by blue_can »

The AFT has never been replaced. Whether it needs to be done or not is unclear to me based on the service schedule. Do you know if there are magnets in the pan to catch waste clutch material - if so I guess it would be a good idea to do this at some point and clean the magnets before they become saturated.

I'm guessing old fluid being responsible is very remote. Stall speed refers to the engine speed at WOT with the turbine section of the torque converter stalled - generally the rpm at stall does give some clues about the health of the torque converter. But this has nothing to do with performance at idle. The only remote possibility I can see would be a very partially applied TCC which could apply excess load to the engine - that or something binding in the impeller section of the torque converter. But in all those cases that should even manifest itself while in "P" or "N".

Battery terminals are in good shape and clean. In fact I made sure to clean them recently when trying to figure this out. Connections all look good as well. However testing the battery is not a bad idea. I do have a tester so I will do a load test and see what that shows. I thought I recently checked that as well but I have been also doing some stuff on another car and getting confused.

The only thing I did on this car prior to this issue was to disconnect the battery and then replace the recir air actuator. While it may be related I have also seen situations where an issue crops up after a repair and think it is related only to find out the issue was unrelated and probably would have occurred whether the original repair was done or not. All adds to the complexity of trying to figure stuff like this out. I did try disconnecting the batteries for a second time once this issue showed up in case something in the ECM had ended up in an indeterminate state or some electronic component had latched up or in a metastable state.
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lannvouivre
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Re: Rough Idle

Post by lannvouivre »

Yes, there are magnets.

Have you let the car run for a long while? When the battery is disconnected, the fuel trims saved by the ECM all get cleared and need to be "relearned." Takes 15-30 minutes, usually. You may also want to clean the throttle body. A clean throttle body and sometimes MAF will bring the current state of the car closer to the base settings of the ECM.
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vibrologist
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Re: Rough Idle

Post by vibrologist »

I have done the drop the pan ATF replacement using Toyota T-IV fluid. There are 2 magnets in the pan.

I think I didn't have the correct definition for stall speed in mind. What I intended to say is that the fluid being old may cause the converter to grab at lower rpm and therefore tug a bit more on the drive train when idling in gear.

change the ATF. This is how mine looked: viewtopic.php?f=30&t=43476#p507231
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blue_can
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Re: Rough Idle

Post by blue_can »

lannvouivre wrote:Yes, there are magnets.

Have you let the car run for a long while? When the battery is disconnected, the fuel trims saved by the ECM all get cleared and need to be "relearned." Takes 15-30 minutes, usually. You may also want to clean the throttle body. A clean throttle body and sometimes MAF will bring the current state of the car closer to the base settings of the ECM.
Yep did all that. I might try disconnecting the battery terminals for a longer period in case there are caps designed to filter the supply in the ECM that might be discharging slowly and preventing a proper cold boot of the ECM when the battery is reconnected.
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blue_can
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Re: Rough Idle

Post by blue_can »

vibrologist wrote:I have done the drop the pan ATF replacement using Toyota T-IV fluid. There are 2 magnets in the pan.

I think I didn't have the correct definition for stall speed in mind. What I intended to say is that the fluid being old may cause the converter to grab at lower rpm and therefore tug a bit more on the drive train when idling in gear.

change the ATF. This is how mine looked: viewtopic.php?f=30&t=43476#p507231
So the pink spot is the new fluid? I thought the Toyota stuff looked clear - at least that's how it looked when the Vibe was new. It does look dark now.

I must admit I could not make much sense of the ATF change schedule -according to the owners manual under some circumstances you don't have to ever change it which sounds odd.
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Re: Rough Idle

Post by vibrologist »

The new fluid is at the tip of the funnel. The old fluid looks dark on the paper but it was solid black when it drained into the bucket.

The manuals are getting more confusing every year. The reason is they are written by lawyers to protect the manufacturer. Some manufacturer's talk about "lifetime" fluids. What exactly is the definition of "lifetime" for a car?
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tribones
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Re: Rough Idle

Post by tribones »

My car has a rough idle after I disconnect the battery. Usually takes a few days for the car to reset its settings in the engine to run well again. My car feels like it will stall at a stop light. I have put it in neutral to rev it up - its never actually stalled on me though. After a couple days it always rev'ed fine. I have an 05.
blue_can
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Re: Rough Idle

Post by blue_can »

vibrologist wrote:The new fluid is at the tip of the funnel. The old fluid looks dark on the paper but it was solid black when it drained into the bucket.

The manuals are getting more confusing every year. The reason is they are written by lawyers to protect the manufacturer. Some manufacturer's talk about "lifetime" fluids. What exactly is the definition of "lifetime" for a car?
Yes I agree it never hurts to change out the fluid. That said I have the Toyota Automatic Transmission Training Notes (primary designed for service techs) and it does say there that with modern fluids color is not a major indicator of failure due to the newer fluids and the materials that go into making up the clutches and bands on newer vehicles. Consistency is more important than color - for example tacky fluid.
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blue_can
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Re: Rough Idle

Post by blue_can »

tribones wrote:My car has a rough idle after I disconnect the battery. Usually takes a few days for the car to reset its settings in the engine to run well again. My car feels like it will stall at a stop light. I have put it in neutral to rev it up - its never actually stalled on me though. After a couple days it always rev'ed fine. I have an 05.
Well it has been a while since I disconnected the battery. I agree initially the idle was very rough sometimes at stop lights and felt like it was going to stall although it never did. It has smoothed out from where it was but does not feel quite the same as before. Another possibility is that the really rough idle after the battery was reconnected caused the mounts to degrade slightly leaving more vibration that before.
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RRich89
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Re: Rough Idle

Post by RRich89 »

tribones wrote:My car has a rough idle after I disconnect the battery. Usually takes a few days for the car to reset its settings in the engine to run well again. My car feels like it will stall at a stop light. I have put it in neutral to rev it up - its never actually stalled on me though. After a couple days it always rev'ed fine. I have an 05.
My '06 Vibe does the same exact thing when the battery is disconnected but it actually stalls at a stop. It will Idle very poorly until it stalls (never while moving thank goodness) and after that it will run as if nothing ever happened. This happened with both my old and brand new battery, I'm wondering if something is a bit off with a CM.
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