Driveablitiy problems


New Member
May 25, 2001
1) Anything under 2500 rpm my car does not feel right. Once in a while when I start the car it will start spuddering. It will cut out and it almost feels like the car is missing. After I get above 2500 rpm everything smoothens out and it runs great:confused:

2) When the car wants to run fine under light throttle there is a small tip in where the car hesitates than smoothens out and runs good. This happens for about 100rpm. I have tried changing the VE table, that helped a little but then the car like to start poping on the decel. Any pointers?
What I would try is to cruise at the rpm where you have the most problem and with the computer hooked up and in the VE map hit L. That will correct your VE in that cell range to your AF ratio. I then pull over and see what it changed to and modify cells around that point to blend in. At low cruise RPM you may need the AF ratios leaner or richer so play with these a little bit to see what the engine needs but first you have to have a good base ve map around your existing AF ratios to get adjustment. My quess is the engine may just like a different fuel ration at this operating condition. What are you running now for AF at this rpm & map

I would also make sure you do not have any enrichment going or leaning programed into the warm up map at operating temp. Should be zero at operating temp. I am sure that was a no brainer suggetions but what the hey.

On your start up you need to check the warm up map and the after start map. I do not have this totally set up either but I am close. You may be over or under fueling on afterstart and warm up on a warm or hot start. Hard to give you too much detail as you need to say under what conditions it occurs, cold start, warm start, hot start and so forth. When it did things like this on my car I wold try to keep it going and when would finally idle I would see what my O2 correction was doing. That told me which way I needed to go typically. I also run EGT's so that is also very helpful.

For the tip in maybe a little more pulse width of enrichment on the AE at that TPS position would clean up that area of the map. Or again it may be too much pulse width as a hesitate could be a rich stumble as well. So try both ways, its so easy anyway but this is where I would start.