p0171 ENGINE SPUTTERS UNDER FULL BOOST?! HELP

[BrockLee GS-T]

I have a 97 gst and i recently put a 14b on it, im having trouble with an o2 sensor i think, so heres whats going on

CEL---p0171--fuel trim malfunction in bank one lean condition

under 8+ lbs of boost, i get a bogging machine gun sputter(makes me feel like its a rich condition)

spark plugs are dark except the very tip of the arm, its white, which makes me think a little lean, but usually the lean plugs ive seen are entirely white??



ive used the search but have only found vague answers, and that may be all there is for this cel, but i need to get it fixed because the car is defiantly being robbed of a lot of power right now, and i really dont want to shell this engine over something stupid that could be fixed realitivly cheaply, any input appreciated

 

[spyderturbo007]

Your CEL is most likely caused by a bad O2 sensor. Do you have, or have access to, a logger? As the O2 sensor wears, the voltage reported to the ECU drops. The ECU senses this as a lean condition and attempts to add fuel to compensate for the "supposed" lean condition.

As the voltage continues to drop there will be a point at which the ECU is not able to adjust enough to correct the lean condition that it thinks exists. It then sets the CEL and tells you that there is a FT malfunction.

On a side note, a bad O2 sensor will not cause a problem at WOT. The ECU does not care about O2 voltage when running at WOT, so you have another problem. Have you done a leak test?

I'm suprised at the condition of your plugs. At 8psi the pig rich factory maps would be more than enough fuel, even at WOT, to compensate for the 14b. An overly rich condition can cause sputtering, but I'm confused at what is occuring. Are you saying that you have been running 8psi and the plugs are white? Or were you running higher boost levels and then turned it down to 8psi?

 

[BrockLee GS-T]

I'm suprised at the condition of your plugs. At 8psi the pig rich factory maps would be more than enough fuel, even at WOT, to compensate for the 14b. An overly rich condition can cause sputtering, but I'm confused at what is occuring. Are you saying that you have been running 8psi and the plugs are white? Or were you running higher boost levels and then turned it down to 8psi?

yeah, me too, they've never seen above 12psi on the t25, 10 psi creep on the 14b, thats it, they're black except the very tip of the arm where its a whiter color, im going to try to check my spark plug wires today and see if that gets rid of the sputtering, i have a feeling they may be the culprit

 

[BrockLee GS-T]

well, i regapped the plugs and ran new wires, it idles a lot better now, but i still have the shotgun sputter going off in 12+ lbs of boost, im dying to get this running right so i can enjoy it again!

for anybody who can answer with experience, if in upper boost it sounds like a shotgun going off and bogs, would that be a rich condition with a backfire or would a lean condition do that, im thinking it has to be running rich for some reason because if it was lean it would just run like a raped ape until it melted a piston??