Unstable idle, car almost stalling at low speeds, need help
Dec 13, 2008, 12:06 PM
#1
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Unstable idle, car almost stalling at low speeds, need help
Hey guys. I did some searching but didnt find a definite answer to this kind of problem.
My Idle is a problem. When I let off the gas between gears or when I switch to neutral before the stop my idle's first reaction is to drop to around 400-500 and almost die. Many times it drops and dash board lights come on like when it stalls but at the last moment it bumps it back up. When it stabilizes it holds around 800 but once in a while still flactuates. Seems like its happening more when its colder, but not 100% sure. And few times when its about to die I think I heard the GM boost solenoid clicking like when it clicks when the boost is coming on.
Also when a V8 car with loud exhaust is revving its engine in front of me my idle drops to 500 or so.
This started happening after AEM intake install and RC1000cc inj and custom tune on 91 and e85. It happens on both maps. My tuner is in process of fixing it, he tried two times but no help.
I have a tactrix cable and a wideband. Can someone help me with this. Its very annoying. Im a fast learner and can follow directions
Any help is appreciated.
Thanks
EVO 9 RS Mods: FPGreen, Cossworth cams, AEM intake, RC 1000cc, FP, TBE, ACT hd etc....
My Idle is a problem. When I let off the gas between gears or when I switch to neutral before the stop my idle's first reaction is to drop to around 400-500 and almost die. Many times it drops and dash board lights come on like when it stalls but at the last moment it bumps it back up. When it stabilizes it holds around 800 but once in a while still flactuates. Seems like its happening more when its colder, but not 100% sure. And few times when its about to die I think I heard the GM boost solenoid clicking like when it clicks when the boost is coming on.
Also when a V8 car with loud exhaust is revving its engine in front of me my idle drops to 500 or so.
This started happening after AEM intake install and RC1000cc inj and custom tune on 91 and e85. It happens on both maps. My tuner is in process of fixing it, he tried two times but no help.
I have a tactrix cable and a wideband. Can someone help me with this. Its very annoying. Im a fast learner and can follow directions
Any help is appreciated.
Thanks
EVO 9 RS Mods: FPGreen, Cossworth cams, AEM intake, RC 1000cc, FP, TBE, ACT hd etc....
Dec 14, 2008, 12:24 AM
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WOW.. Guess your Tuner does not know what the problem is either, since your in Cali there has to be another shop that can help out. Your mods and God knows whats on your ECU leave way to many scenarios.
Dec 14, 2008, 12:43 AM
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I had an idle issue about 6 months back, which caused my engine light to keep coming on. and believe it or not I had checked many different things and the problem was the throttle cable not being positioned correctly, and had slipped, therefore causing rpm to drop to 500 at idle. may seem to easy and a dumb answer to be the problem, but check it dude, it may save you many hours of pointlessly checking. oh and this was the case of a few evo's around my area.
Dec 14, 2008, 12:51 AM
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Thanks for a response. Ill definetely check it out first thing in the morning. Was yours too loose or too tight? Was it slipping off that plastic piece where the spring is at?
I had an idle issue about 6 months back, which caused my engine light to keep coming on. and believe it or not I had checked many different things and the problem was the throttle cable not being positioned correctly, and had slipped, therefore causing rpm to drop to 500 at idle. may seem to easy and a dumb answer to be the problem, but check it dude, it may save you many hours of pointlessly checking. oh and this was the case of a few evo's around my area.
Dec 14, 2008, 01:34 AM
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It was to loose, imagine the throttle cable being able to slip, so as you keep pressing the pedal over time, the cable gets pulled out. I did a check and when I had my foot fully to the floor, I was actually only at around 88% throttle instead of 100%. so you never know, this might be your problem and you might get some extra performance!
Dec 14, 2008, 10:04 AM
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When I put my FIC 1050's in I got proper values for them from the guy I got them from and all was fine for a good while. Then suddenly, started to have idle issues.
My problem was one of the vacuum lines to the EGR came off. I did a pressure test of my intake and was hearing air coming out near the TB which I originally thought was the TB seals. I took it off and saw the EGR hose sitting there.
On a side note, I also tested an HKS BOV and a new factory metal top Mitsubishi BOV at work to 20 PSI and found that both leaked even at pressures as low as 5 psi. The HKS leaked regardless of a shim on the spring. My stock plastic BOV held 20 psi fine though.
After I put the stock BOV back on, did some vacuum hose plumbing, the problem went away. Unless your injector settings are off, my bet is a small vacuum leak which is easliy detected for about 5 bucks worth of stuff from home depot.
/brox
My problem was one of the vacuum lines to the EGR came off. I did a pressure test of my intake and was hearing air coming out near the TB which I originally thought was the TB seals. I took it off and saw the EGR hose sitting there.
On a side note, I also tested an HKS BOV and a new factory metal top Mitsubishi BOV at work to 20 PSI and found that both leaked even at pressures as low as 5 psi. The HKS leaked regardless of a shim on the spring. My stock plastic BOV held 20 psi fine though.
After I put the stock BOV back on, did some vacuum hose plumbing, the problem went away. Unless your injector settings are off, my bet is a small vacuum leak which is easliy detected for about 5 bucks worth of stuff from home depot.
/brox
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Dec 14, 2008, 10:53 AM
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Ok. Its deninetely not the throttle cable. I checked and everything is fine there.
Hmm, BOV? I dont have any other BOV to swap it with right now. Is there a way to troubleshoot it some other way? Can it really be a BOV with those simptoms?
I ve done a boost leak test - no leaks. If one of the vac lines was off I would hear it, right?
Now when the rpms drop to 400 or less right before the stalling there is clicking sound coming from drivers uderhood side. Kinda like GM boost solenoid clicking when u hitting boost. And after rpms bump back up it stops.
Any other Ideas? Thanks
Hmm, BOV? I dont have any other BOV to swap it with right now. Is there a way to troubleshoot it some other way? Can it really be a BOV with those simptoms?
I ve done a boost leak test - no leaks. If one of the vac lines was off I would hear it, right?
Now when the rpms drop to 400 or less right before the stalling there is clicking sound coming from drivers uderhood side. Kinda like GM boost solenoid clicking when u hitting boost. And after rpms bump back up it stops.
Any other Ideas? Thanks
Dec 14, 2008, 09:42 PM
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I didnt remove the battery for a long time. Not sure how can it be connected wrong.
Everything started happening after intake install and a tune.
Could I mess something up while installing the intake? Can something be wrong with MAF itself?
Everything started happening after intake install and a tune.
Could I mess something up while installing the intake? Can something be wrong with MAF itself?
Dec 17, 2008, 10:17 AM
#13
The reason that the car bogs down when a motorcycle or a loud car passes by is that the MAF is picking up that vibration and is flaking. Happens on most all evos with aftermarket filters.
Did you disconnect you battery while installing the intake. The EVO takes a few drive cycles to relearn again. Could take a couple days
Did you disconnect you battery while installing the intake. The EVO takes a few drive cycles to relearn again. Could take a couple days
Dec 17, 2008, 10:20 AM
#14
It sounds MAF related. Log your O2 Feeback Trim and see if it goes out of watch when the stalls happen. I'm currently working on a car with the same issues. I made it better with adjustments to the Idle Stepper Map and MAF scaling, but it wasn't perfect. I'm now tuning it for open loop idle to alleviate the issue. It's promising so far ...
Dec 17, 2008, 10:06 PM
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It sounds MAF related. Log your O2 Feeback Trim and see if it goes out of watch when the stalls happen. I'm currently working on a car with the same issues. I made it better with adjustments to the Idle Stepper Map and MAF scaling, but it wasn't perfect. I'm now tuning it for open loop idle to alleviate the issue. It's promising so far ...
