OK... already tried the Search option... and i didn't find anything useful. So here's the deal:

Car shows code for TPS. Replace TPS. Car starts right up, runs great. Catches on like the 3rd turn each time. This morning, i woke up... started the car... started right up, drive it around... everything is running good... then i come home and turn it off. I go to start it again a few minutes later, and no start... just turns and turns and turns and turns. Go to check for Codes.... no codes showing (except for code 12 of course). So... i check for spark... got spark... check for fuel pressure... got 42psi... get the injector light out... light blinks like it should. Car still doesn't start. Turns over all day... but no catch. After a while... i found an extra MAF and figured i'd try that... right after i put it in the car started right up. I turned the car off, try to crank it over again.... and ..... no start.

I've gone through the service manuel's check list like 3 times... and its getting kinda fustrating. Its dark out now... so i'm going to take a break and hope i can get some good idea's from some helpful thirdgen people.

By the way... car specs:

1989 Iroc-Z, with the 5.7 and the 700r4.


Well, hope someone can help.

Joker

 

Joker,

You're taking all the easy ones away. There are a few things necessary to operate a gasoline piston engine:

Fuel;

Ignition;

Compression;

Timing.

You've established that you have ignition. You have fuel pressure, and your injectors are presumably operating. All you need is compression and the correct valve and ignition timing.

Checking the ignition timing should verify both, since the distributor is driven by the camshaft. You should be able to verify the timing with a light.

Compression is dependent on correct valve timing and mechanical reliability of the engine.

Another wildcard in our EFI systems is the ESC system. Timing could be drastically affected by the system, so you might want to disconnect the bypass connector and try starting that way. If the ESC is skewing the ignition timing, spark could be severely retarded.

 

ok... here's an update:

got the car started by changing the Coolant Temp Sensor and adjusting the timing. I disconnected the brown/black wire and set the timing to 6 before TDC. The car ran good with it set at that... a little rough though. After reconnecting the wire, it wouldn't start. Disconnected wire, started up. Re set the timing so that when the wire was connected it would read 6 BTDC, which with the Brown/Black wire disconnected was O degrees.

I'm trying to figure out why the timing is getting moved so much by the computer, and why it is running so ruff. I just put new plugs, rotor, cap, and wires on it.... so its kinda a mystery right now. Maybe i'm just tired from spending all day just to find the coolant sensor was bad. Any help would be appriciated.

Joker