Cold / Hot Idle A/F Problems

[ProchargedCobra]

I did a couple of searches and could not find anything on this.

Once the car is warm I set the VE tables to get the desired idle characteristics. The car idles best around 12.5-13.0 : 1.

Then the next day when the car is cold, it is extremely rich, like 10:1 on initial startup. Progressivly leans up as car warms up/

There AE fuel vs. CTS has no enrichment at the startup temp, and the same thing goes for the CTS.

Any thoughts on this. Is there anywhere else I could take out fuel enrichment based on coolant temp, or heat soak.

If I set the ve tables to idle at a decent a/f when cold, then when it gets warm (heat soaked) it is very lean (14:1) and does not idle well that lean.

 

[troyk]

Does your car idle faster when cold? This might put you in 1 cell off from when the car is warm. VE cell numbers can change a lot near idle to try to fix troubled areas.

Does your car hunt at idle? This means your in going inbetween cells with different VEs? The only reason I bring this up is, this might be an indication to having a different VE when warm as apposed to cold, since it might be in a different cell.

I'm not an expert, just throwing ideas out.

 

[bobc455]

Originally posted by ProchargedCobra

>>>Once the car is warm I set the VE tables to get the desired idle characteristics. The car idles best around 12.5-13.0 : 1.

I hope that you mean you are setting the A/F table to make it idle there...

>>>Then the next day when the car is cold, it is extremely rich, like 10:1 on initial startup. Progressivly leans up as car warms up/

That sounds like the warm-up enrichment table doing it's thing- no problem there. Engines need to be richer when cold.

>>There AE fuel vs. CTS has no enrichment at the startup temp, and the same thing goes for the CTS.

Not quite understanding you- do you mean that the tables are zero'd out? Or do you mean the tables are programmed but not functioning?

>>Any thoughts on this. Is there anywhere else I could take out fuel enrichment based on coolant temp, or heat soak.

Well that is the whole fuction of the "CTS correction" table (under the "temperature correction" selection). Have a look at that and see if you understand.

>>If I set the ve tables to idle at a decent a/f when cold, then when it gets warm (heat soaked) it is very lean (14:1) and does not idle well that lean.

Set your A/F table for something richer then- 13.5:1 is not uncommon.

I'm confused- I thought you said above that the car was set to idle at 12.5 - 13:1. Remember, the VE table is ONLY to make the target A/F ratio match the actual A/F ratio. The VE table is NOT used to set your A/F ratio, that is the job of the A/F ratio table.

-Bob Cunningham