I have this ongoing problem:

[SeanMc]

Start, die, start, die, start, run for a bit, die, start, die, start, die, start, give it gas so it keeps running, but let off the gas, die. But then after a bit, it will start, almost stall out, but then it will bring the rpms back up, and it's fine other times, it starts beautifully no matter the temperature. There is a slight fuel smell, but not a "crap, I just flooded the engine" smell.

Only codes I get are 139 (O2s not switching) and 225 (knock sensor), but no CEL. Does this sound like O2 sensor(s) would do?

 

[SHOtimer]

Sounds like a fuel/air problem to me, if it was a spark problem I don't think it would start in the first place. Is your fuel pump original or is it making inconsistent noises? Do you have a fuel pressure gauge?

The IAB also seems to be suspect. Try giving it 1/4 of gas when trying to start it in this condition, that will open up the throttle plate to let gas in, it that cures the problem you are looking at a faulty IAB.

Also, I had this problem with my Oldsmobile, and I have heard people on the forum here having the problem. If the ECT is giving the computer the totally wrong tempturate then the mixture that the computer is trying to start the car with won't work. Which would explain how different temperatures affect it.

Doug

 

[SeanMc]

Hmm, IAB was replaced not to long ago with one out of a 90 SHO that was working. I don't have a fuel guage, but I may invest in one. The pump sounds just fine, and was replaced about 2 months ago.

 

[SHOtimer]

I would be suspect of the IAB if it is off a '90 SHO. How long has this problem been around?

Doug

 

[SeanMc]

A while. Even before I had the engine rebuilt. We tested the old IAB, and it wouldn't open or close, but the "new" one did. ** hum.

 

[jedhead]

I think most all your drivability problems would be gone with an LPM or Tweecer. 3.3L with stage 2 cams with a stock MAF and no LPM does not make a good tune. We need to make a junkyard run for the MAF. I wonder if Vadim has a program that will work with the stock maf too?

Bob

 

[SeanMc]

Well if not this weekend, how about next weekend? Did you run by SHOShop last night? Oh, and once everything is started, I really don't have any drivability problems.

 

[jedhead]

Well if not this weekend, how about next weekend? Did you run by SHOShop last night? Oh, and once everything is started, I really don't have any drivability problems.

Vadim is supposed to have my headers for me this Monday. I will ask then.

Bob

 

[TYSHO]

3.3L with stage 2 cams with a stock MAF and no LPM does not make a good tune.

And especially with bad o2's!