Stock ECU gurus..

hottscennessey

hottscennessey

DONT BE A BITCH!
Jun 3, 2005
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Richmond, VA
I've re-set my ECU a couple times in the past 6 months. I've noticed the following w/ my wideband. After I first re-set my ECU my AFR's are rich rich rich. Gradually as time progresses (say over the course of a month) the AFR's start to lean out. More specifically I could be in the 10 AFR range and after a month I'll be in the high 11 ARF range.

Has anyone ever noticed anything like this? I'd consider the ECU richening the mixture (retarding timing) to be a common thing due to knock.. but why leaning it? Obviously this wouldn't be an issue if there were a real problem. But I was just wondering if you gurus out there had any input.
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
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Yeah but there has to be a root cause. Closed loop boost? That's odd. At WOT the ECU is much more dependent on things because well, it's open loop. I'd check fuel pressure, coolant temp sensor, TPS, and airflow. A month's a long time though. I'm assuming no codes. Piggyback??
 
hottscennessey

hottscennessey

DONT BE A BITCH!
Jun 3, 2005
3,137
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Richmond, VA
So Nick you're thinking either the ECU is trying to make my charge more difficult to light. Sorry lol. I just didn't follow that post.

Another thing to keep in mind is I do run MAF-T with a GM MAF sensor which probably does become heatsoaked being positioned above the valve cover/next to the turbo. The ECU would be be calibrating fuel trim for an AFM that is very difficult to headsoak in its stock position. I just thought about this with the code.. cant believe I didnt think of it before.
 
hottscennessey

hottscennessey

DONT BE A BITCH!
Jun 3, 2005
3,137
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Richmond, VA
JJ I couldn't disconnect the MAF because its only under WOT that I see the drift. 24 doesn't flash the CEL, I've only founding it by running the code diagnostic. And my "piggyback" or so i call it is the MAF-T.
 
hottscennessey

hottscennessey

DONT BE A BITCH!
Jun 3, 2005
3,137
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36
37
Richmond, VA
Maybe the ECU is seing the heatsoak from the MAF and pulling fuel to avoid an overly rich mixture (because of the "hot" intake charge). Maybe the ECU made this a change to the longterm fuel trim after repeated heatsoak-ings. That could be a longshot tho. haha.
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
9,439
0
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Redacted per Title 18 USC Section 798
It is, but at least on the Karman you can lift a wire. You might be able to do that on the MAF. It's a hotwire MAF right? Sounds like you may be onto something yourself. It just took a little prodding to get you thinking ;)
 
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