Back to the Tuner - idle/short shifting
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From: Merritt Island, FL
Back to the Tuner - idle/short shifting I recently swapped a 402ci and 4l80e into my '02 4WD Tahoe and went to a professional chassis tuner. The motor runs really strong over 3,000 rpm. If I am cruising down the freeway and romp on it, it down shifts good and flys. The problem I am having is idle/starting quality and short shifting off the line at or near WOT.
I called the tuner and he made an appointment for me to bring it in and hopefully solve the problem. Before anybody gets critical with my tuner, in all fairness I discovered an electrical gremmlin that was causing multiple codes. I was getting a MAF code so I replaced the MAF. That code went away but then I got a TPS code and replaced it. Then I got another code for the MAP and replaced it but still got a code once in awhile. While driving down a washboard road, my motor was cutting in and out which lead me to a bad connector on the MAP. That is now fixed.
I was able to monitor my MAP reading at idle which is between 69 & 71 kpa at 825 rpm. It reads 102 kpa with engine off. TP is .4%. I don't know what my IAC readings are. What questions or input should I be giving to my tuner so he can properly address the issue? Here are my engine specs if that will help:
402ci, stock L92 heads and truck intake manifold, 10.4 CR, F.A.S.T 92mm TB (no hole in plate), Cam is 228/238 .571/.585 113 lsa +4, 8.1L Marine Injectors, 4L80e w/2400 converter.
My tuner uses HPT software if that helps.
Don't get too technical with me or you will be over my head. I know carburetors fine but I am computer tuning challenged. Thanks in advance for your input.
I called the tuner and he made an appointment for me to bring it in and hopefully solve the problem. Before anybody gets critical with my tuner, in all fairness I discovered an electrical gremmlin that was causing multiple codes. I was getting a MAF code so I replaced the MAF. That code went away but then I got a TPS code and replaced it. Then I got another code for the MAP and replaced it but still got a code once in awhile. While driving down a washboard road, my motor was cutting in and out which lead me to a bad connector on the MAP. That is now fixed.
I was able to monitor my MAP reading at idle which is between 69 & 71 kpa at 825 rpm. It reads 102 kpa with engine off. TP is .4%. I don't know what my IAC readings are. What questions or input should I be giving to my tuner so he can properly address the issue? Here are my engine specs if that will help:
402ci, stock L92 heads and truck intake manifold, 10.4 CR, F.A.S.T 92mm TB (no hole in plate), Cam is 228/238 .571/.585 113 lsa +4, 8.1L Marine Injectors, 4L80e w/2400 converter.
My tuner uses HPT software if that helps.
Don't get too technical with me or you will be over my head. I know carburetors fine but I am computer tuning challenged. Thanks in advance for your input.
Last edited by Duntov1967; Jun 18, 2012 at 11:55 AM.
