2001 silverado 4.8 po121 after cam install...shifts funny HELP!!
my son has a 2001 Silverado 4.8 we installed a tr 224 cam and a set of 243 heads,3600 fti converter headers etc etc...having a problem with a code po121 and the transmission shifts funny...I know on hpt u can disable the code but how do you correct it so the transmission will shift back to normal...thx
Solve the tps problem first, dont disable. Then post a log, the tune, and a more detailed description of "shifts funny".
here is the tuned file
http://www.hptuners.com/forum/showth...fts-funny-HELP!!
P0121 is a predicted value diagnostic. Those predicted limits can go out the window with mods such as cams. IMO predicted value diagnostics are for stock vehicles, not modified ones.
WAY TO MUCH TIMING! From about 0.60 down lower timing from 30's to 26 max, and probably lower for tuning purposes. Nothing else stood out, have to see log.
here is log file...didn't see any knock with that timing
You need to drop your full throttle shift rpms because of the converter. Drop them down to 5500 and see where that gets you, then you will have to play with full throttle mph and rpm to get it where you want it. Right now your hitting the rpm limiter at the shift.
yes I did correct that...I guess I need to make cruise log file trans seems to shift early and lockup then unlock like its not getting the correct tps info...does the rest of the file look ok
I see a few issues. What's the gearing in the rear end?Originally Posted by 1fast86
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