question about the PCM "Learning" after tuning
Thread Starter
TECH Senior Member
Joined: Nov 2001
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question about the PCM "Learning" after tuning Hi guys <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
I have a general Q for you about the PCM learning after LS1 edit changes to the PE tables.
I am running a stock MAF with screen removed, COT turned off in my program, 27 degrees advance and about 13:1 on the AF ratio on the dyno. Graph is pretty smooth and everything looks nice.
My question is will the computer over time richen things up a bit or keep things around the same if no Knock retard is present? My LTRIMS were probably in the +2-3 range tops with the screen removed on both banks.
Your thoughts are appreciated!
Chris
I have a general Q for you about the PCM learning after LS1 edit changes to the PE tables.
I am running a stock MAF with screen removed, COT turned off in my program, 27 degrees advance and about 13:1 on the AF ratio on the dyno. Graph is pretty smooth and everything looks nice.
My question is will the computer over time richen things up a bit or keep things around the same if no Knock retard is present? My LTRIMS were probably in the +2-3 range tops with the screen removed on both banks.
Your thoughts are appreciated!
Chris
Thread Starter
TECH Senior Member
Joined: Nov 2001
Posts: 10,341
Likes: 1
Re: question about the PCM "Learning" after tuning yes but that is not my question though.
Ok say you have zero Ltrims on both banks (ie: running a bone stock MAF with screen)
Now say you do an LS1 edit tune and get your WOT AF ratio at 13:1 on the wideband through the alteration of PE tables. Over time will this AF remain relatively constant if LTRIMS are fairly static? (STRIMS will obviously vary according to weather etc) but I am curious if after a month you go back on the dyno what would the net change in AF be in general from your original tune? Leaner or Richer?
Thanks again,
Chris
ps- this hasnt happened to me but I am just curious <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
<small>[ September 09, 2002, 04:34 PM: Message edited by: Chris ARE 360 ]</small>
Ok say you have zero Ltrims on both banks (ie: running a bone stock MAF with screen)
Now say you do an LS1 edit tune and get your WOT AF ratio at 13:1 on the wideband through the alteration of PE tables. Over time will this AF remain relatively constant if LTRIMS are fairly static? (STRIMS will obviously vary according to weather etc) but I am curious if after a month you go back on the dyno what would the net change in AF be in general from your original tune? Leaner or Richer?
Thanks again,
Chris
ps- this hasnt happened to me but I am just curious <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
<small>[ September 09, 2002, 04:34 PM: Message edited by: Chris ARE 360 ]</small>
Re: question about the PCM "Learning" after tuning I really think that this depends on the car. All I can really site is my own experience.
When I first tune the vehicle, I start out lean. After about 200 miles of driving the PCM gets done with all of its tests and starts callibrating (what, I don't know, but my a/f ratio begins to change).
Original tuning usually leaves the car a little lean. After about 2 weeks of driving (~1000 miles I think) the car is noticeably richer, and will continue to run in this richer state until I reset the PCM. I haven't had a chance to get the car on the dyno to see this because I have been reprogramming so much lately.
FWIW, I think the change in a/f ratio is very little.
When I first tune the vehicle, I start out lean. After about 200 miles of driving the PCM gets done with all of its tests and starts callibrating (what, I don't know, but my a/f ratio begins to change).
Original tuning usually leaves the car a little lean. After about 2 weeks of driving (~1000 miles I think) the car is noticeably richer, and will continue to run in this richer state until I reset the PCM. I haven't had a chance to get the car on the dyno to see this because I have been reprogramming so much lately.
FWIW, I think the change in a/f ratio is very little.
