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02-05-2019, 10:56 PM | #1 |
Drives: 2007 Hatch Join Date: Feb 2019
Location: Norristown, PA
Posts: 14
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Stumbling idle when stopping.
Hello all,
I'm new here and recently was gifted a 2007 hatch with a few issues. Most were easy to remedy, squealing serpentine belt, hazy headlights, out of round rear drums and things of that nature. One thing that has eluded me has been an idle issue that driving me nuts. While coming to a stop the car feels like it is going to stall. Just before a complete stop, no matter how brief, the idle will dip to sub 500 RPM, I'm guessing that figure due to it being auto with no tach. It gets to where it feels like it will stall then it will recover. While sitting at idle the RPM will jump around. It has yet to die on me, but feels like it wants to 100% of the time while stopping. Here are some things I have done to try and fix the issue. New air filter New plugs Cleaned MAF sensor Cleaned TB without removing it, therefore I'm not sure of the condition behind the butterfly. Used a cinder block to open the TB with the key on to clean around the plenum, but not behind the butterfly valve. The car has 188k miles on it and I'm very impressed with the mileage over my 2010 Nissan Titan 4x4. I have seen many posts similar to this but not exact and all of them fizzeled out before a solution was given or found. I know a fair amount around a car, but when it comes to fuel injection I'm kinda lost. If I'm overlooking anything, please give me some guidance. There is a lot of info on this forum and I hope to get many years of help and offer a lot in the future. Thanks in advance, Jeremy |
02-06-2019, 12:49 AM | #2 |
Hello there!
My Yaris is also humming on very low RPMs when idling. AFAIK this is normal for this car. |
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02-06-2019, 08:22 AM | #3 |
Drives: 2003 Mach 1 Join Date: Oct 2008
Location: Georgia
Posts: 293
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I had a similar issue but it turned out the alternator that I had recently replaced was not tightened down enough. I had cranked down the bottom bolt pretty tight but it was still not as tight as it needed to be. My mechanic got it on there tight and the car stopped a good bit of what I felt was mechanical vibration. I felt like I was in danger of overtigtening but I guess it had a bit to go.
My car has 350k+ on it... we also discovered through the whole process that the vibration I thought was an idle issue was actually the motor/transmission mounts failing. I was only getting a vibration when the car was in gear and I had the AC on at a stoplight when the car was under load. Now that we've pinpointed the mounts failing I can feel that the vibration is coming from the direction of the transmission and lower motor mounts. There's also an Idle Control Valve that can be problematic too... I believe it's located under the throttle body? Those are fairly delicate and expensive to replace per some of the info I've read so be careful if you try to clean it! |
02-06-2019, 08:30 AM | #4 |
Drives: 2007 2-door hatchback Join Date: Jul 2016
Location: USAnotCA
Posts: 750
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Yaris idle speed measure multimeter frequency
Manual tranny warmed-up idle is 600 rpm. Mine was, and likely is, exact, per a multimeter set on "frequency" standing up in the driver's side dash cupholder. (Yes, that isn't a little glove-box as it might seem...notice how it will crush contents when closing.)
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02-06-2019, 11:25 AM | #5 | |
Drives: 2007 Hatch Join Date: Feb 2019
Location: Norristown, PA
Posts: 14
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Quote:
When I got the vehicle I needed to replace the alternator tensioning bar since the original was cracked on the top and was making the alternator sit at an angle making the worst belt squeal ever. When I removed the alternator it had rubber dust all over the side from the last belt being chewed up. So I know the alternator is nice and tight and charging the system as well. The car belonged to my mother in law then my brother in law and I was their "mechanic" for the last 6 years. I replaced the motor mounts about 3 years ago around 145k miles so they are good as well. When I did the throttle body cleaning I didn't see an Idle control valve like on older Toyotas I have worked on. I think since the TB for the yaris is throttle by wire, it simply adjusts the butterfly to make an air change at idle. When I cleaned the TB I didn't notice an IAC vent in the plenum. Those would all make the vehicle feel like it is shaking for sure, but the only one I would think of causing the near stalling would be the TB. I think if the weather holds up I will remove it and clean it on both sides to see if a difference is made. Thanks again! |
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02-06-2019, 11:29 AM | #6 | |
Drives: 2007 Hatch Join Date: Feb 2019
Location: Norristown, PA
Posts: 14
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Quote:
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02-06-2019, 01:07 PM | #7 |
Drives: 2007 2-door hatchback Join Date: Jul 2016
Location: USAnotCA
Posts: 750
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Multimeter tachometer frequency dwell Extech
This decade or two old Extech tach is auto-ranging in all functions and has one rotary knob for two off positions and 12 functions. One is labeled FREQ and % (where the little manual said that % is duty-cycle, which I was able to use to read dwell on a not-electronic V8 points distributor...33.3% being 30 degrees dwell, I recall)
On frequency-to-rpm conversion, you've got 60 seconds/minute and the OBD pin is making two signals per crank revolution. It is one of the end pins in two rows of 8. (Search terms tachometer and OBDII should get you to threads on this) I got ground from the cigar lighter socket. I liked seeing how idle RPM worked through warm-up, and help getting my ear calibrated for rpm. (The rev limiter spec is 6000 rpm. I like to use 5000 and get there once in awhile for engine health...usually merging or entering a traffic stream in second or third and then skipping a gear in the upshift.) Really just need to consider owner's manual "max speed in gears" for 2 and 3 for most all driving conditions. |
02-10-2019, 08:25 AM | #8 |
Drives: 2008 Yaris 3DR Hatch MT Join Date: Dec 2018
Location: Harrisburg, PA
Posts: 80
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OP: Have you:
1. Cleaned the idle air control valve (under the TB)? 2. Cleaned the VVT oil control valve? 3. Replaced the oil control valve filter? |
02-10-2019, 11:16 AM | #9 | |
Drives: 2007 Hatch Join Date: Feb 2019
Location: Norristown, PA
Posts: 14
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Quote:
I do have another question. If the TB is removed from the vehicle, can the butterfly be moved slowly to clean the back side of it and the edge? I have seen videos and forum posts saying it's ok to do so, while others say to never manipulate the butterfly EVER. I won't be flipping it rapidly, just slowly open it to clean it thoroughly, while trying to not strip the gears inside. |
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02-10-2019, 11:28 AM | #10 | |
Drives: 2008 Yaris 3DR Hatch MT Join Date: Dec 2018
Location: Harrisburg, PA
Posts: 80
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Quote:
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02-16-2019, 08:03 PM | #11 |
Drives: 2007 Hatch Join Date: Feb 2019
Location: Norristown, PA
Posts: 14
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Today I got the throttle body gasket and got to work. Removed the TB and cleaned it front and back. Installed new gasket and slapped it all back together. It is a lot more responsive and the stumbling idle when braking is gone now.
Next task is passenger lower control arm replacement. Went to get an alignment and the ball joint is mangled pretty good. |
02-16-2019, 08:12 PM | #12 |
Drives: 2007 Hatch Join Date: Feb 2019
Location: Norristown, PA
Posts: 14
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Here are the before and after pics of the back side of the TB. It was pretty filthy.
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02-17-2019, 08:34 AM | #13 |
Drives: 2008 Yaris 3DR Hatch MT Join Date: Dec 2018
Location: Harrisburg, PA
Posts: 80
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Looks good! The tolerance between the butterfly and the bore on the TB is DNZ (damn near zero), so this should certainly help. I have installed an oil catch filter after the PCV and now my TB stays squeaky clean.
Last edited by 2bz; 02-17-2019 at 08:56 AM. |
02-17-2019, 12:41 PM | #14 |
Drives: 2007 Hatch Join Date: Feb 2019
Location: Norristown, PA
Posts: 14
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How often do you drain the catch can? Did you buy one or make your own?
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02-17-2019, 01:49 PM | #15 | |
Drives: '08 2zr swapped Vios M/T Join Date: Oct 2012
Location: Caledonia Ont.
Posts: 2,938
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Quote:
Probably around 4 ounces every 6-10k km
__________________
No one ever wants to give a Yaris the point by... |
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02-17-2019, 02:49 PM | #16 | |
Drives: 2008 Yaris 3DR Hatch MT Join Date: Dec 2018
Location: Harrisburg, PA
Posts: 80
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Quote:
https://www.harborfreight.com/mini-a...ter-68225.html https://www.harborfreight.com/38-in-...ece-63957.html |
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02-17-2019, 02:56 PM | #17 | |
Drives: 2008 Yaris 3DR Hatch MT Join Date: Dec 2018
Location: Harrisburg, PA
Posts: 80
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Quote:
https://www.harborfreight.com/mini-a...ter-68225.html https://www.harborfreight.com/38-in-...ece-63957.html |
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