Hello my name is Derek and I bought a 93 z28 a few month ago. As far as engine mods go it has a Vortech t-trim running about 6 psi . the whole fuel sytem has been updated 42lb injectors 255 in tank pump and so on. For the longest time I had an oil leak that was pretty bad, I found that it was the rtv behind the intake. Before I found this I did a compression test to check my rings it was fine. In the process I broke my tps but didn't know at the time well it took forever to figure it out but I fixed and it ran a lot better. now its acting up again. it has to turn over about 6 times before it starts and then u have to hold it at like 2 grand so it will run. I'm completely stumped now and don't know what to do. I hope its something simple. i am goin to take it to put it on an obd1 machine next week. anyways If anyone has any ideas on what my problem could be. Now on the other hand in your opinion what should my next mods be. I'm looking for about 600 hp so I know i need to do internals I'd like to push about 10-15 lps boost and I plan to do the whole valvetrain and heads wha would you guy suggest in parts and what not that I should buy.
thanks
-Derek

 

Check fuel pressure.

 

how would i fix it if its screwing up b/c when it does run the fuel pressure does act up really weird so what could i do to fix that?

 

Probably the fuel pump.

 

thank you very much ill look at that this evening

 

the previous owner boosted a 93 car with no engine internals upgrading? I would talk to the previous owner and see if he had in fact done some internal build.

 

i know the internals have not been touched b/c i knew the previous owner real well before hand its only on 6psi no more ever and that shouldnt hurt stock internals he had planned to go through it later on but i got it before that and now i plan do internals soon

 

well i am almost certain that its running way too rich we adjusted the tps and that seemed to help its got a lot of hesatation and u can smell how rich its running what can i do to fix this problem and what is the tps voltage supposed to be??

 

anyone have any ideas??????

 

i am pretty sure a blower tune is supposed to be a little rich, how bad is it

 

You might check in the forced induction forum.

 

How does the blower system add the extra fuel for boost? Does if have an FMU, a boost-referenced fuel p[ressure regulator, or was the ECM tuned for a 2-bar MAP sensor? Who did the tune? That fact that "when it does run the fuel pressure does act up really weird" may indicate a problem with the FMU, or with the fuel pump or fuel pressure regulator.

Give us the specifics of what "really weird" means...... what is the fuel pressure at idle, with the vacuum line off the FPR? What happens when you reconnect the vacuum line? When the engine is under load, how does the fuel pressure vary? It will be normal for the fuel pressure to rise during boost, and to drop very low on closed throttle deceleration.

The TPS sensor will only be a problem if the voltage falls outside of the range that the ECM will accept. Anything between 0.20-0.90 Volts at closed throttle should be OK. Most people try to set it around 0.50-0.67V. If its "bad", it should set codes. Have you tried flashing the DTC codes on the SES light (only possible on 93 LT1's)?

 

well hte fuel pressure straightned out and teh ecm is tuned for the 2 bar thing there is no fmu i have one tho but the pressure increases when underboost so that was never a problem its just running really rich and you can adjust the tps for that some what but its really touchy and when we think we have it right after a bit of running it acts up again goin back to running really rich im about to take it right now to get the computer flashed an checked for codes it is throwing a ses light but thats been tehre and last tiem we had it put on a machine it said the tps was bad so we changed it and im goin to checkit again. its normally at 40lbs on the gauge at idle and almost 50 when underboosti believe thats all right.