: Idle air Duty cycle


jetrinka
05-04-2009, 09:03 PM
I have been having idleing problems with my car. When coming to a stop, I push in the clutch to let the RPM's drop and once I come to a stop, the RPM's drop below 500 in some instances before coming back up to normal idle (set to 800). Almost like the car is halfway trying to die.

Anyway. I know the ignition and fuel systems are fine. Car makes good vacuum at 22" at idle. Makes great power as well. Only problem is this weird idling issue. MAF is clean. This leads me to think its the idle air control valve. So I logged its duty cycle while drive around town to find that it really drops when coming to a stop. Now you must forgive me as I don't know what the values I got mean really. Just cruising in gear I get around .55. (this is logging "idle speed valve duty cycle") When I come to a stop, in neutral, it drops to as low as .189 in some cases, very quickly before recovering to right around .25-.30 at regular idle. Makes me think the idle air is sticking slightly and not recovering fast enough. The idle also drops quite a lot when putting the AC on and turning the steering wheel while at idle. I logged some other things I deemed useful. (lol i have no idea...)

I have one datalog that is a pretty good one. You can really see the downwards spikes. I will try and upload it on here. If I can't, just PM me with an email and I will send it to you.

jetrinka
05-04-2009, 09:05 PM
So it turns out I can't attach files to a post... I don't think. PM me for the datalogs.

jetrinka
05-04-2009, 09:42 PM
I just remembered how to use some computer black magic illinipo taught me. haha.

http://i266.photobucket.com/albums/ii265/jetrinka/data.jpg

illinipo
05-04-2009, 11:14 PM
very hard to make out rpm with stft the same color...

from the sound of what you described i would guess you dont have enough dashpot preposition, but that is a guess without looking at your tune or your datalog yet.

the A/C issue is another part of the tune, easily corrected. Contact your tuner.