A little background: I bought this car with blown head gaskets. The car ran and drove when I got it. Just finished doing head gaskets and put in Bosch III injectors. Now the car will not run properly. It would not start up but we assumed that was due to timing, but we timed it as well as we could by ear, then hooked a timing light up to it and got it right on. We have gotten it to run for a couple of minutes but after that it wont do anything more than kick over a little. I've looked over everything I've done and cant see that I've missed anything but any suggestions would be great!

 

........ Any Codes ? ..... what is the timing set at ? ..... did you disconnect the EST wire when setting the initial timing to 6 BTDC ? ......... this can be found near the wiper motor ........ double check that the engine coolant temp sensor on the front of the intake manifold is plugged in .....

 

Have you confirmed the fuel pressure?

fuel relay & pump function?

DTC displayed prior to the repairs?

have you read the flash codes?

There is LOTS to do.
Did you get the FSM for the 87?

There is no way to diagnose a C4 or ANY computer fuel injected engine without knowing the settings, adjustments and how it works together. Its not grandpas Oldmobile....
This 87 L98 might look like a typical SBC but its not...its a very complicated engine mngt system that has very little room for error. It has to have the basics spot on or else you;re gonna walk. I know,. I have one sitting right outside...

Get the fuel pressure, confirm the pump runs 2 secs at key ON, make sure fuel stays UP and does not bleed down immediately. Check your MAF relays and ALL the inj wire harness. There is NO part of that harness that can be disconnected or damaged and expect the engine to run.

Things to focus on:

fuel pressure
fuel pump& fuel relay AND oil pressure switch (this is for fuel !)
est wire (base timing)
air leaks
TPS setting (.54v)
all sensors & GROUNDs..harness grounds, not battery. There are a hundred harness grounds. About 5 by the oil filter that are critical.
MAF & relays.

Spend $75 on a set of used FSM books and follow the diagnostic flow charts.

Get some info and tell us and we can help.

 

Finally got it running, disconnected the mass air flow sensor and it ran better, after a little carb cleaner the car runs great, thanks for your reply's!

 

so, you;re going to run it with the MAF d/c?
seriously?

that was just a diagnostic tool,



-> NOT HOW YOU FIX THE PROBLEM ! ! ! ! !

 

I disconnected the MAF to determine that it was the problem, cleaned it, reconnected it and the car runs better than ever...