Thought it was fuel cut (WRONG)

[fast95eclipse]

I have been having a problem with my car since I upgraded my turbo and all the fuel and the rest of the supporting mods (i guess its when it started) , it bucks at about 3K RPM and sometimes at 4K and if I stay on the throttle it will keep cutting out like im not getting sparks and I can see a bunch of black smoke in the rear view mirror behind me. If I let of the throttle alittle it will begin to pull again. I thought it was fuel cut but I looked at my HZ's on my S-AFC and the most HZ's I get is 1998hz so I found out its not fuel cut. I looked at my spark plugs (1 colder then stock) to make sure they were'nt fouled out and they looked good, alittle white but looked good. They were gapped at .040 which was wrong so i put them all to .030 and then I test drove the car again and it seemed to help alittle but it still cuts out slightly with air changes. Me and my friend go out and tune my car and we can get the heitation to go away with the afc and it wont buck for awhile until the air tempature changes; so for example I will tune it in 80 degree weather and I will get it to pull good but when I go back and drive it at night it will start hesitating and bucking again. It seems like the air temp affects how my car will buck, the hotter the weather the less the buck the colder the more it will buck. Could it be a sensor or can the plugs be really bad or something. I have a keydriver chip so thats another reason I know its not fuel cut. I've looked for boost leaks and found none, but my BOV (greaddy) might be leaking. My plugs arent that old and my wires as well are new (NGK). sorry if it dosnt make sence its had to decribe with words. Any thing to help me would be appreaciated.

[sbiggi]

sounds like maf overrun, but I doubt it if you have a 2g maf

switch your afc over to 1 sensor
karmen
and line graph mode


if it looks like a richter scale then you got maf overrun.

another thing to look for is on the logger. You can see dips in the Injector Duty Cycle, it will go from say 85% to 78 and back to 85% all in a couple hundred rpm.


-Seth

[fast95eclipse]

Well I went out and tried that and the line isn't perfectly straight, going up it has some squiggle line and when I shift it drops all the way down and then goes up with squiggle line again. Since I regapped my spark plugs its gotten alot better, it dosent hisataite as long and it dosn't do it every time. Sometimes it well just pull very solid with out hesitation. Before I regapped them it would jerk bad and it would do it until I let off of the throttle alittle. Maybe my plugs just got bad in 10,000 miles or something. Anything else I can check or try?

[biglady112]

Well most DSM's need to be gapped to .028". I had the problem with my 1G. New plug wires and a regap fixed the problem. But it still did it every now and again. This was due to too much fuel and too much duty cycle. I had 680CC's with a cozmo fuel pump. The cycle on the logger stated it was at 122%. I turned the fuel pressure down and the problem went away. I also had this problem with a friends 2G. Put new wires and regapped the plugs he had, and magic. The problem went away. So that is my recommendation.
Steve

[fast95eclipse]

what did you set your fuel pressure to? since I have the key driver chip it should compensate for the 660cc i have, right?