Cold start problems - using FAST ECM with wideband O2
Hi All,
I had my 85 tuned on a dyno after I installed the FAST and wideband O2 sensor. She drives very well indeed when hot, but on cold start (which the tuners couldn't touch as the car was warm when I arrived) I have the following problems:
1. Car will not run on her own from cranking - I have to 'catch' the throttle and tickle it for about 5 seconds, after which she idles - albeit roughly.
2. For the first 5 minutes of running, any attempt to enagage drive stalls the engine, UNLESS I rev to about 1500 and hold it there first. Again - in and out of drive when warm with no issues
3. On pulling away, she coughes and splutters with misfires - any additional throttle opening only makes matters worse.
I have tried playing with the various afterstart tables in the CCCOM software, but nothing I do seems to have any effect - and of course, I only get 5 minutes to try before she warms up and the problems go away!
Can anyone give me some simply instructions of what I should adjust to try and resolve these issues?
My first attempt was to try and adjust IAC position versus Temp - ie bring the idle speed up a bit to prevent stall on engaging drive. No effect on idle. I can see the IAC position resolutely tracking well shy of where I set it.
If you haven't already guessed, someone like me having access to laptop tuning is just plain dangerous! I know next to nithing!
So if anyone could give me any tips, I'd be very grateful.
BTW The base-idle is correctly set. That was a simple procedure even I could manage!
I had my 85 tuned on a dyno after I installed the FAST and wideband O2 sensor. She drives very well indeed when hot, but on cold start (which the tuners couldn't touch as the car was warm when I arrived) I have the following problems:
1. Car will not run on her own from cranking - I have to 'catch' the throttle and tickle it for about 5 seconds, after which she idles - albeit roughly.
2. For the first 5 minutes of running, any attempt to enagage drive stalls the engine, UNLESS I rev to about 1500 and hold it there first. Again - in and out of drive when warm with no issues
3. On pulling away, she coughes and splutters with misfires - any additional throttle opening only makes matters worse.
I have tried playing with the various afterstart tables in the CCCOM software, but nothing I do seems to have any effect - and of course, I only get 5 minutes to try before she warms up and the problems go away!
Can anyone give me some simply instructions of what I should adjust to try and resolve these issues?
My first attempt was to try and adjust IAC position versus Temp - ie bring the idle speed up a bit to prevent stall on engaging drive. No effect on idle. I can see the IAC position resolutely tracking well shy of where I set it.
If you haven't already guessed, someone like me having access to laptop tuning is just plain dangerous! I know next to nithing!
So if anyone could give me any tips, I'd be very grateful.
BTW The base-idle is correctly set. That was a simple procedure even I could manage!
TIA
Regards
Steve
You need to adjust the commanded AFR when cold to a richer number. When it is cold it will be in open loop and there should be a table for open loop operation. Move the cammanded AFR 10% richer when it is cold and see what it does.
I have not used the FAST software for a few months so I am not sure exactually where the table is but look for a commanded AFR table when in open loop.
Corvette Store
Cold start problems - using FAST ECM with wideband O2
