I'm having a strange idle problem after I made some minor adjustments to idle tuning. After uploading the slight adjustments, car ran fine but then the car seemed to have a power issue of some sort with the lights flickering on the dash and rough idle. I shutoff the car (I was at a stop light) and turned it back on. It seemed to be idling rougher after I started back up. I pulled into a parking lot immediately and noticed the following oddities:
My Spark timing at idle went from averaging 0 to averaging 25 with a lot of bouncing around of the torque management
My STFT were suddenly way out of wack - typically +4-5% at idle to now +15-20% at idle
My cylinder airmass is down a lot from typically 280ish to now 150 to 160ish
Part throttle driving was completely normal and with normal trims. So, I just reverted my tune back to where it was before and the idle issue did not change at all. I then unhooked the battery for about 10 mins (to try and clear out any bad stored data) and no change once again.
I have some E in the tank and it is reading properly at 35% alcohol and commanded AFR seems appropriate (wideband lambda bouncing around 95 to 105) at idle despite the big +trims. Exhaust does smell a bit more than usual as well (lean).
Any ideas out there? With the electrical mayhem is it possible my vehicle hasn't "caught" up to the alcohol content yet after the reset? Its acting like it after a fillup of E where my trims are really high for the first 10mins or so of driving until the ECU catches up. But I've already driven it long enough for it to smooth out, but hasn't. The biggest oddity is the spark timing/cylinder airmass at idle going from basically 0 or slightly negative to 25ish average and losing around 130 on the airmass at idle...
I have included a log before and after just a couple hours apart which shows the drastic change at idle (11:30am to 1:57pm). Both logs are of the exact same tune.22-09-23 11-30-33.hpl22-09-23 13-57-30.hpl
The issue is coming on pretty intermittently as you can see in both short logs. When coming to a stop it'll idle really rough, bouncing around and you'll see on the spark timing that is jumps a lot. Other times after driving a little and coming to a stop, it'll idle normally - timing pretty steady in the 4-9 range and doesn't jump around a lot, idle feels normal.
I also notice that throttle position drops from around 20% to 17-18% and my cylinder grams drops from 250-260 in the normal idle to 190-200 when idling rough. I've also seen it drop all the way down to 13-14% and cylinder airmass dropping to 160's as well.
Any ideas? Did the electrical issue cause a problem with idle learn? Is there an Idle Relearn procedure I should try?
Tried the Idle Relearn Procedure - still have the funky idle. Its hard to tell if it is better though - i'd like to think it is, but i'm still getting wild swings in my idle spark timing that comes and goes.
If my idle is set too low (currently 710 on 232/240 cam) would that cause the idle relearn to not complete if idle is not stable enough? Idle doesn't swing a ton (70-80 rpms) or stall (average is 716 rpm when set to 710 rpm), the biggest issue with when idle spark timing goes haywire is car bucks a bit uncomfortably when stopped and in-gear. I had it set to 850rpm idle for quite a while before I set it lower to 710. Gonna try setting back to 850 and give it another go.
I just don't understand the swinging in timing from 5 to 26, back down to 5 to 26 in fractions of seconds when idle.....
After increasing my idle to 850rpms and putting over 50 miles driving around without making any other adjustments, it appears my idle has been improving. I'm not sure how long the idle relearn process is supposed to take, but it is certainly much better and improving each time I drive the car. But, idle still is not as smooth as previously. However, there is one other very interesting thing to note:
*Given no other changes to my tune my idle spark timing is now consistently positive, averaging around 13* degrees compared to 2* degrees on average previously.
It appears that what ever electrical hiccup I experienced had totally wiped out all learned idle cells and with the relearn, spark has improved which was something I had been fighting with for a long time adjusting VTT tables with little to no success. I guess Idle Relearn FTW.
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