So I just bought an '89 Z28 wiht a built 350ci TPI. Ever since I bought it there was this problem with "cold start" because after sitting it would turn over after about 5 seconds of crank time, fire up to 1500rpms, but then immediatly drop down to about 400rpms and inevitably bog out unless you gave it a little gas. After starting the car and giving it just enough gas to keep it running for 1-2 minutes the problem went away and the car started right up with no idle problems...800-900rpms in P everytime. The problem only returned after the car sat for more than 4-5 hours.

NOW...after we just upgraded plugs, wires and a distributor cap and my friend advanced the timing to about 10 degrees and the car ran fine last night. Today I went to start it and it gave me the usual cold start problem but this time it wouldn't respond to me giving it gas. I could barely keep it idling about 400rpms and definitely can not drive it more than 10ft before it bogs out?

what do you guys think?

fuel pump...iac valve...tps valve...plugs/wires...anything?

My main concern here is $$$ to fix it. Should I be worried...other than this problem the engine runs fine.


On a side note...I upgraded to Mobil1 synthetic motor oil only to find out from the guy I bought the car from that the motor was not built for synthetic and that running it could cause problems. I've only ran it for about 50 miles but I did a couple 1/4 mile runs...could this cause any problems so soon???

thanks in advance..

 

Engine could not run on synthetic? Never heard that before. Change your fuel filter?

 

Yea..apparently the pistons and other internal components were not built to run synthetic! I've never heard of this before...but that is what the kid that I bought the car from told me. It is a 350ci one pc. truck block
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I just had a retard moment. My fuel gauge hasn't been working but all the others have. I put $25 in last night with some octane booster. I drove about 60 miles not to mention about 10 1/4 mile runs in a 3-4 hr period. It just occured to me that the loss in fuel pressure or spark could be due to simply 'no gas'. If this is the case feel free to label me the official "dunce".

HAHA. I'll find out tomorrow morning.