ECM Secrets & Tuning Hints
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I took mine out before mounting my new tb to fwi coupler last week before I went to the track. No noticible improvment, and in fact I did not match my PB (although close) but I got a lot of slip off the line (with slicks) so I attribute my non PBs to that and not the removal of the MAF screen. Either way it doesnt seem to have done much for me.
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Originally Posted by DrJay
Very interesting find, good job! I'm still reading it right now but as far as the scantool readings the ST and LT fuel trims are where to look for the 128 number. LT being long term fuel trim, and ST being short term. LT is the average, but ST you can watch change as you drive.
I found it also interesting that according to the article, the only thing the computer learns is BLM and BLM cell values, and it learns very quickly. When I put my screen back in, the BLM was back to the old values within 30 minutes and 10 miles of driving.
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I was noticing leaner than normal for me 02 numbers at the track, and a little higher KR. I think I'll put my MAF screen back in tomorrow and see if it clears up.
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Originally Posted by Rogue
I was noticing leaner than normal for me 02 numbers at the track, and a little higher KR. I think I'll put my MAF screen back in tomorrow and see if it clears up.
This is just a theory, so don't take my word for it. Try it for yourself.
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Originally Posted by GreenMachine
Originally Posted by Rogue
I was noticing leaner than normal for me 02 numbers at the track, and a little higher KR. I think I'll put my MAF screen back in tomorrow and see if it clears up.
This is just a theory, so don't take my word for it. Try it for yourself.
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Originally Posted by Rogue
Originally Posted by GreenMachine
Originally Posted by Rogue
I was noticing leaner than normal for me 02 numbers at the track, and a little higher KR. I think I'll put my MAF screen back in tomorrow and see if it clears up.
This is just a theory, so don't take my word for it. Try it for yourself.
#17
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My LT is 138 and my ST is 128 until i put it in gear, then it switches to 135. If my understanding is correct then an AF calibrator cannot correct this because it changes the AF ratio and not the preasure itself right? or would the ECM change the FP when it sees that my MAF readings are different. How bad is this for my car?
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Originally Posted by jachin
My LT is 138 and my ST is 128 until i put it in gear, then it switches to 135. If my understanding is correct then an AF calibrator cannot correct this because it changes the AF ratio and not the preasure itself right? or would the ECM change the FP when it sees that my MAF readings are different. How bad is this for my car?
The scantool I'm using lets you see what cell you're in, and the LT does change over time, but at a slower pace then the ST. When I switched in/out the MAF screen, the LT ramped over a couple minute period. Anyway, the bottom line is, if it is always at a high number and never changes over time, it'* probably running lean. With my MAF screen in, my LT varies between 120 and 130.
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I was reading about this about a week ago and it seems its capable of 0-255 and even moving up a block. Linky time:
http://www.chevyhiperformance.com/techarticles/49738/
Scroll down to Understand GM EFI
http://www.chevyhiperformance.com/techarticles/49738/
Scroll down to Understand GM EFI
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Originally Posted by DrJay
I was reading about this about a week ago and it seems its capable of 0-255 and even moving up a block. Linky time:
http://www.chevyhiperformance.com/techarticles/49738/
Scroll down to Understand GM EFI
http://www.chevyhiperformance.com/techarticles/49738/
Scroll down to Understand GM EFI
I mentioned, so normally it doesn't go from 0 to 255.
GM programmers often clamp the block-learn to minimums and maximums closer to 128. When any block-learn cell hits the maximum allowable value, a data trouble code is set, the Service Engine Soon dash light illuminates, and the computer defaults to open-loop operation.