Idle Hunting On Stock Car
Posted: Mon Dec 25, 2017 4:01 pm
Merry Christmas! Shame today feel like the only day I've had this year to really dig into my car!
I've got a stock 2012 SI with 105k. Previously I had posted about having inconsistent Trim values while trying to tune AFM Flow. Due to being out of town for work it's been a few months since I could even touch the car. I was due for plugs so replaced those and I replaced the upstream O2 sensor at the same time. I cleaned the MAF sensor with MAF cleaner and went back to trying to tune AFM flow this week. I still seemed to be getting inconsistent values and I feel like I've rules out a lot of things but still haven't found the issue. Related or not I also started having problems with idle hunting when warm, returning to stock eq did not resolve but I have remained there for the time being.
For the time being I'm hoping that solving the idle hunting will solve my AFM/Trim issues.
I've heard air in the coolant can cause this, there was air at the top of the rad but a top off and burp hasn't fixed the issue.
I've used an unlit propane torch to look for vacuum leaks but could not locate one (I am no expert at this to be fair, so not entirely ruling this one out)
I pinched off the PCV valve and the issue was not resolved.
Throttle body has a tinge of carbon but nothing that looks bad to me.
The thing that makes me want to discount a vacuum leak is that my trim values (again all stock) can total -25%+ longterm, in the attached log it drops to -15%L and -24%S momentarily, I would think that if I was looking at a vacuum leak the trim values would be positive or at least increasing since before I was having idle issues if this is just an out of spec MAF sensor.
At the same time AFM.v seems to be rock steady related to TPlate.
Hopefully someone has some input. Kind of afraid to drop this car off at the mechanic for equal reason of being stupid simple or really expensive.
Attached log is idle warm up, short drive, and idle hunting.
Thanks,
-Nick
I've got a stock 2012 SI with 105k. Previously I had posted about having inconsistent Trim values while trying to tune AFM Flow. Due to being out of town for work it's been a few months since I could even touch the car. I was due for plugs so replaced those and I replaced the upstream O2 sensor at the same time. I cleaned the MAF sensor with MAF cleaner and went back to trying to tune AFM flow this week. I still seemed to be getting inconsistent values and I feel like I've rules out a lot of things but still haven't found the issue. Related or not I also started having problems with idle hunting when warm, returning to stock eq did not resolve but I have remained there for the time being.
For the time being I'm hoping that solving the idle hunting will solve my AFM/Trim issues.
I've heard air in the coolant can cause this, there was air at the top of the rad but a top off and burp hasn't fixed the issue.
I've used an unlit propane torch to look for vacuum leaks but could not locate one (I am no expert at this to be fair, so not entirely ruling this one out)
I pinched off the PCV valve and the issue was not resolved.
Throttle body has a tinge of carbon but nothing that looks bad to me.
The thing that makes me want to discount a vacuum leak is that my trim values (again all stock) can total -25%+ longterm, in the attached log it drops to -15%L and -24%S momentarily, I would think that if I was looking at a vacuum leak the trim values would be positive or at least increasing since before I was having idle issues if this is just an out of spec MAF sensor.
At the same time AFM.v seems to be rock steady related to TPlate.
Hopefully someone has some input. Kind of afraid to drop this car off at the mechanic for equal reason of being stupid simple or really expensive.
Attached log is idle warm up, short drive, and idle hunting.
Thanks,
-Nick