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How quickly does the PCM adjust after rocker install?

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Old Apr 23, 2007 | 01:37 PM
  #11  
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Originally Posted by agrazela
Originally Posted by 67Goat
Great - Thanks all for the feedback. I did have the battery disconnected for two days while I was working on it, so it probably is starting from scratch. I might re-scan in a couple days to see how it is going. I was just getting worried because I heard usually it would learn after about 30 minutes of normal driving and it was using quite a bit more fuel than normal. I swapped the PCM to ZZP'* a few days ago and it seemed to run fine then, so pretty sure that is not it.
1.95 rockers is a big change, and bigger changes do require longer fuel trim learn times.

You'll be bouncing alternately between overly lean / overly rich for awhile, so drive like a grandma for at least a few days to a week. ONLY AFTER a couple hundred miles and some definite improvements in the way the car runs should you even consider gunning it.

Do you have a scantool? If not, beg, borrow, or buy one, 'cause without it you'll be blind. As others have said, scan for KR and LTFT and STFT and O2. Also scan rpm, TP%, MAP, MAF, IAT and IPW.

Silly question perhaps, but did you tell zzp about your 1.95 rockers when you ordered the PCM? (In other words, is that PCM tuned to the rockers?)
Thanks - Good info. We did an initial scan using a Snap-On Scanner. It looked normal because it was only idling. I'll take it easy for about a hundred miles or so and re-scan. When I got the PCM from ZZP, I got the rockers at the same time. Zoomer recommended just going with their standard 1.0 program with no other changes, so that is what I have.
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Old Apr 23, 2007 | 02:59 PM
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so the question is does the ZZP PCM setup for the 6K shifts
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Old Apr 23, 2007 | 03:32 PM
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Hmm, when i went to the track it was the day after i did the rocker install. I wonder if there would be a difference in times now the pcm has learned them. Maybe not but it is nice to think there maybe an increase at the track haha
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Old Apr 24, 2007 | 12:47 AM
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Originally Posted by 1993 SLE
so the question is does the ZZP PCM setup for the 6K shifts
I'll know in 100 miles. I'll be really bummed if they did not set up correctly ....I'm still waiting for an e-mail response to a question I sent them last Wednesday.
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Old Apr 24, 2007 | 01:27 AM
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Originally Posted by firebuick
what are we looking for when you say to check MAP MAF and IPW can i check these whit my aeroforce i know i have maf sensor and map frequency but dont know what is the normal reading .i do know about KR and IAT thank you
With MAF and IAT, we can calculate VE (volumetric efficiency) at 100% TP at any given MAP and rpm (this is really for my own curiosity more than anything, frankly).

LTFT'* and STFT'* will tell us whether the PCM is even able to adjust fuel trims enough for that mod (likely it is, but certainly worth checking)...that will be dependent on how far off the programmed VE table is from reality; if fuel trims are maxing out at a large negative number, that'* not good.

IPW (injector pulse width) will tell if the injectors can handle the added fuel flow.
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