which tables to control warmup spark?

[Redline Motorsports]

I have noticed on several cars that the timing advance on cold startup is very erratic. It only seems to last for 10-25 seconds and then stabilizes. Which tables effect this condition and whys does it happen?

I also final figured how to post these screen shots! Oh boy!!:notacrook:



http://img171.imageshack.us/img171/8656/warmupsparktk7.png

[TAQuickness]

That's an interesting question you pose. I don't see the WB AFR in that screen shot. It's possible what you see is a fueling condition resulting in the swings in spark, map, and RPM. I would let the car cool and use the BiDi to identifiy the culprit.

[Redline Motorsports]

I have been getting my fill of really utilizing FS lately so I guess I spaced the WB data! This combined with the variety of cars I work on will do that!

AFR on this particular car are very stable. I was using the WB off the dyno to make this statement as I was watch it as the motor was warming up. I have seen this on many cars on initial cold startup. Does spark follow AFR in any of the tables? Isn't there a startup timing table as well that includes a decay rate??

Its not really a huge issue on most of them but a few would have a slight bouncing idle and as soon as it leveled off it smoothed right out.

Howard

[AGRO]

sounds like the cat light up spark b5901 is causing it

[Redline Motorsports]

sounds like the cat light up spark b5901 is causing it

What if COT is disabled?

[AGRO]

What if COT is disabled?

Doesnt make a difference, cot is a fuel adder to keep the cats cool after some abuse, the cat light up spark is to help heat the cats upon start up (retards timing from your absolute), basically for emissions, the more timing reatrds the hotter exhaust gas temperature gets.

[Redline Motorsports]

Doesnt make a difference, cot is a fuel adder to keep the cats cool after some abuse, the cat light up spark is to help heat the cats upon start up (retards timing from your absolute), basically for emissions, the more timing reatrds the hotter exhaust gas temperature gets.

duh! Thats right.......I guess for learning purposes I should do warm up log on a stone stocker and see what happens. I work on so many modified cars that I never real take the opportunity to analyze the root tune to see what GM has implemented as a basis. Now I have to find something stock!

I'll figure it out.

Thanks

Howard

[SSpdDmon]

sounds like the cat light up spark b5901 is causing it
Ditto. Check the cat light-off enablers and set them to something that'll prevent it from coming on.