Ok this is driving me insane. When the car is cold as in just started. I drive away. If I mat the throttle I wont get above 4000RPM. It just sits there. Surging and chugging making all kinds of noises out the muffler and it stinkd like fuel. Even if i put it in nuetral and floor it it stops at 4000RPM. Now heres what I did. I set my timing from 8 deg to 6 deg. And dropped my fuel preassure from 62psi to 55psi. That cleared the problem up. Car was running great. But..yesterday the problem returned. I am completley lost. Is this a possibility? I have Hyperbeutectic Pistons. Not sure on the spelling. I know they channel heat very well and take some time to heat up. You can here some very minor slap when its cold sometimes. The engine shop and some books said that was normal due to there design. Is the Knock sensor maybe picking this up and seriously retarding timming? Can i disconnect it and try a run without it to see? Please help I cant stand this anymore

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1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)

 

Your fuel pressure is still too high. If you REALLY need 55 psi, then you should look at bigger injectors.

 

Can you tell me what I should be running the preassure at? I hooked up a DVOM to the O2 and was getting 890mv at WOT. I checked this as I was driving the car. I have no problem dropping my preassure im not at 55 cause I think its a good thing. I thought that was just about right. Any input would be great. Thanks

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1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)

 

I think stock fuel pressure is 46.5 or 48??? Also DON'T rev it up when it's cold. It causes engine damage. If you just start it up and then try to rev out it's no wonder it spits and sputters. Wait til it's actually warmed up/operating temperature.

 

Using the o2 isnt really a good way to tune the car, they arent much good besides finding the median point between rich and lean... beyond that its pretty much useless.