MAFT/LTFT's and Dragstrip use
Re: MAFT/LTFT's and Dragstrip use when i goto the track, my 02's are always richer then the street.
i try leaning them out and it just wont happen.
ive noticed that my ltrims are around -10 at idle and ive also noticed on A-tap that my ltrims are negative for the first few readings then they goto 0 for the rest of the run.
should i be leaning out those instead of my 02's?
i try leaning them out and it just wont happen.
ive noticed that my ltrims are around -10 at idle and ive also noticed on A-tap that my ltrims are negative for the first few readings then they goto 0 for the rest of the run.
should i be leaning out those instead of my 02's?
Thread Starter
12 Second Club
Joined: Aug 2002
Posts: 115
Likes: 0
From: Tampa, Fl
Re: MAFT/LTFT's and Dragstrip use The other factor here is IAT and ECT. Sitting in staging lanes not moving any air will cause IAT to rise (my last couple runs my IAT shows 130F!! And ECT of 198-208F). I haven't got a close look on the IAT/ECT/Spark tables, but doesn't the PCM make some changes to the spark advance when you are seeing the temps that high? If so, wouldn't the timing change affect your A/F ratio?
I guess to attempt to answer Chris' question: I have not seen the PCM report positive or negative LTFT's when running in Open Loop (actually I have.. once. I have the log of it.. but I can only imagine it was a fluke.. only happened on one bank). What I was saying was, I thought the PCM used the last known good value for the LTFT's for manipulating the fuel trims just before it zeros them out. So ofcourse they won't show negative or positive, however the fuel trims themselves will be manipulated. Not sure how one could monitor this, other than reading the O2's (which, the heat will also affect! grr..).
I guess to attempt to answer Chris' question: I have not seen the PCM report positive or negative LTFT's when running in Open Loop (actually I have.. once. I have the log of it.. but I can only imagine it was a fluke.. only happened on one bank). What I was saying was, I thought the PCM used the last known good value for the LTFT's for manipulating the fuel trims just before it zeros them out. So ofcourse they won't show negative or positive, however the fuel trims themselves will be manipulated. Not sure how one could monitor this, other than reading the O2's (which, the heat will also affect! grr..).
