Idle issues out of nowhere
Jan 14, 2014, 12:35 PM
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Idle issues out of nowhere
Hi everyone,
I just started having some trouble with my idle quality. This happens on all tunes the car has been on, so I don't think its tune related. This is also across fuel from 5 different stations, and both 91 and 93 octane. Pump install was recent, but this issue did not crop up immediately when the pump was installed, but a week after.
What is going on is that when cold, idle AFRs are floating from 14.5 to 15.2 ish. That's fine with me. Once it warms up ( i think I can pinpoint right on the temp gauge when it goes to closed loop) it will fluctuate from 12.5 to 17 on my UEGO. It seems like these are real AFRs, as when I try to start rolling casually, it will bog when rich, and when i see it go lean, I feel it stumble/possibly misfire a bit. Fueling when under load seems normal along with cold idle, which leads me to believe it is a closed loop problem.
Any ideas?
Plugs are stock gapped to .022
Boost leak test good up to 30 psi (didn't check higher)
Mods pertinent to issue:
Perrin intake
Stock cut up airbox
3 port
3 inch turboback
Walbro 255
Racelite flywheel and HD 6 puck (ugh)
I will post cold and warm logs tonight. My initial inclination is ISCV or NB o2 going bad... however I simply don't have a ton of experience with Evos. My ISCV idea is backed by the fact that I have high load shift throttle hang/rpm spikes, which apparently can be cured by ISCV map changes.
Any help appreciated!
I just started having some trouble with my idle quality. This happens on all tunes the car has been on, so I don't think its tune related. This is also across fuel from 5 different stations, and both 91 and 93 octane. Pump install was recent, but this issue did not crop up immediately when the pump was installed, but a week after.
What is going on is that when cold, idle AFRs are floating from 14.5 to 15.2 ish. That's fine with me. Once it warms up ( i think I can pinpoint right on the temp gauge when it goes to closed loop) it will fluctuate from 12.5 to 17 on my UEGO. It seems like these are real AFRs, as when I try to start rolling casually, it will bog when rich, and when i see it go lean, I feel it stumble/possibly misfire a bit. Fueling when under load seems normal along with cold idle, which leads me to believe it is a closed loop problem.
Any ideas?
Plugs are stock gapped to .022
Boost leak test good up to 30 psi (didn't check higher)
Mods pertinent to issue:
Perrin intake
Stock cut up airbox
3 port
3 inch turboback
Walbro 255
Racelite flywheel and HD 6 puck (ugh)
I will post cold and warm logs tonight. My initial inclination is ISCV or NB o2 going bad... however I simply don't have a ton of experience with Evos. My ISCV idea is backed by the fact that I have high load shift throttle hang/rpm spikes, which apparently can be cured by ISCV map changes.
Any help appreciated!
Last edited by -Hum-; Jan 14, 2014 at 04:24 PM. Reason: more infos.
Jan 15, 2014, 08:45 AM
#2
EvoM Community Team Leader
My guess would be Narrowband issues. What do your LTFT Low + STFT's look like? When cold it is not running in closed loop which is why you are seeing stable numbers there. It sounds like your problem is when closed loop kicks in, which to me would point to the narrowband 02 sensor.
Jan 16, 2014, 12:22 PM
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LTFT Low is at about 10, and short term just climbs... I'm replacing the NB o2 tonight.
I double checked my leak checking with a can of carb cleaner last night, and couldn't find any issues. Pretty well convinced the NB is the issue.
I double checked my leak checking with a can of carb cleaner last night, and couldn't find any issues. Pretty well convinced the NB is the issue.
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