need help...
ive got a problem with my 88 firebird cutting out during light acceleration after 45mph. It seems to be down on power and pull alot of timing. Then under light throttle it cuts in and out and chugs/hesitates. This is usually after its heated up (bout 5-10 min of driving). also on cold start the idle is usually around 1K-1200 for a minute or two before dropping down to 850-900 in park. shouldnt i be 800 idle, 600 in drive.

specs:
350 LO5 tbi
new fuel pump, new egr, injectors (55#), fuel filter, replaced TB gaskets and did adjustable fuel pressure mod (turned the screw 2 full turns to up the pressure and didnt help any. timing is 0, ive tried advancing a couple degrees but experienced no change.

I just need some expertise to point me in the right direction. Could it be bad chip? i had a 350 chip burned for me online. could it be 02 sensor? should i advance timing even more (6 degrees or so) or will that hurt it, im runnin 93 octane?

thanks guys

btw had to post this in tbi section. mods if you want you can delete my similar one in southeast section, hasnt had much action there.

 

i got a new o2 sensor. im going to swap it soon. is there only one on these cars? ive also replaced the plug wires with msd 8.5s and put in bosch spark plugs.

Any other help?? Has anyone experienced a similar situation?

 

ttt cmon guys anything at all

 

I know just enough about TBI to be dangerous, but since none of the more experienced have responded, I'll try.

I first started fooling with TBI a few years back when I converted my rock crawler (truggy) to an 89 TBI unit. The first thing that got pounded into my head is FUEL PRESSURE! Any time it acts up, the first thing you check is fuel pressure, both at idle and load conditions. There is no point looking at anything else (unless the symptoms point to a probably cause like vacume leaks) until you know the fuel pressure. Second, either manually check the sensors (TPS, O2, etc.) or hook up a data logger (I use WinALDL) to see what's out of whack. WinALDL (or other scanner) won't help with fuel pressure since there is no pressure sender for the computer.

 

does it un good in OL? that is under 160 deg F. the 02 is not used till it hits 165F or so. coolant temp sensor? one would think you would see a CE light come on for a sensor malfunction. do you have another chip to remove and replace. my bad chip throws a CE real fast.

 

well last time i advanced the timing a couple degrees and didnt make much difference. it still felt like it had no power. but it doesnt hesitate until the car heats up. so yea good in open loop. then it goes to hell after cruising for a few min. Also, the only other chip i have is for a 305. The current chip is a 350 mail order one. the 305 one runs waay worse.

im thinkin of advancing the timing to about 6*. could be coolant temp sensor i guess. i dont get any CE lights.

thing is when the car had the 305 knock/esc module, 305 injectors, stock fuel pump it still hesitated once i added the 350 chip. so adding all those parts did nothing to help. also, the 305 chip would throw on a CE light and go into a limp mode and drive absolutely aweful.

vacuum leak??