stft question/wot fueling strangness/min inj pw
08-26-2005, 02:26 PM
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stft question/wot fueling strangness/min inj pw 1. If ltft's are disables does the pcm remember stft at all or are they cleared when the ignition is turned off.
2. I have problems when I first crank the engine and if I go wot within 5 mins of start up I will get very rich pe readings, this occurs even when the engine is up to temp I do have a 180 stat but the normal running temp is around 170. After several wot runs the wot fueling will fall into place but it is those intial couple runs that have me stumped.
3. also min injector pulse width Ive noticed on trucks the the default pw is 0 after 3600 rpms where as f bods have the same value throughout the range any explaination or thoughts on why?
2. I have problems when I first crank the engine and if I go wot within 5 mins of start up I will get very rich pe readings, this occurs even when the engine is up to temp I do have a 180 stat but the normal running temp is around 170. After several wot runs the wot fueling will fall into place but it is those intial couple runs that have me stumped.
3. also min injector pulse width Ive noticed on trucks the the default pw is 0 after 3600 rpms where as f bods have the same value throughout the range any explaination or thoughts on why?
08-29-2005, 12:14 PM
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To answer the first question...stft's are not remembered when ltft's are disabled - even with the ignition on. They are nothing more than an instantaneous correction to achieve the desired AFR. The average of the stft corrections is what is used to determine ltft's or the percentage you're off from stoich with your tune.
The second question I'm not so sure about. I know as the motor is heating up on mine, there are timers at work. If you're not in CL because the HO2S's aren't seen as "ready" by the PCM, then you're running off of the OLFA table (which most likely is something other than an EQ of 1.00). Check your fueling tables and you may find what you're looking for.
Have no clue about the 3rd question. Maybe because DFCO works slightly different in a truck vs. an f-body? I wouldn't be concerned if it came that way. Now, if it were maximum p.w., then I'd be concerned.
The second question I'm not so sure about. I know as the motor is heating up on mine, there are timers at work. If you're not in CL because the HO2S's aren't seen as "ready" by the PCM, then you're running off of the OLFA table (which most likely is something other than an EQ of 1.00). Check your fueling tables and you may find what you're looking for.
Have no clue about the 3rd question. Maybe because DFCO works slightly different in a truck vs. an f-body? I wouldn't be concerned if it came that way. Now, if it were maximum p.w., then I'd be concerned.
