tamatt27

I've got the '94 LT1/T56 in my '88 Trans Am. I finally got it to start and idle last weekend. It's very tempramental though. I've got to crank it and let off several times in order for the engine to start.
This weekend, the car wouldn't start at all. The computer's not grounding the injectors. I've ohm'd out all of the PCM grounds and they're all less than 1.5 Ohms, and all of the PCM Ignition and Battery voltages are getting 12V.
Is there any way for ya'll to tell me some reasons why the computer's not grounding the injectors? It's got a brand new opti, and cap and rotor. I've got the VATS, EGR, AIR, etc deleted.
The only thing I can think of is the PCM's bad? I've got a spare '96 OBD2 PCM. Can I hook that up and will it work enough to see if the injectors fire?

Also, is there a wire on the connector coming from the opti that I can baackprobe and see if there's any kind of activity on it?

TexasLT1

check ALL of your grounds and redo them if you have to, add another ground strap if you need to, but just make sure you've got all the grounds where they need to go first.

tamatt27

I did that this weekend. We went through every PCM ground...traced the wires..Ohm'd them out. Every PCM ground is less than 1 Ohm, except one that goes into a solder splice that also grounds several other sensors. Than one is around 1.5 Ohms. That still shouldn't be enough to hinder that ground.
Is there a wire in the opti connector that I can backprobe and see if that optical sensor is giving a signal to the PCM to fire the injectors?
Tonight, I'll see if I can find if there's any other sensors that get their ground from the RED PCM connecrtor (same as the injectors) and see if they're getting a good ground too.
I'm just running out of time and patience with this damn thing.

thebigwelsh

Im not positive if there is a crank senor or not? Either way the crank sensor usually drives your spark, and a cam sensor typically controls fuel. If ya made sure everything is gravey with the opti-spark, better check it over again, because your problems probably resides in the opti-spark. Forgot to mention it could be an ignition module, The module controls spark and fuel. Ive seen it cut out only fuel on more than one occasion.

TexasLT1

no crank sensor on these, opti is used as a cam position sensor. even if something was wrong with it, you'd still get injector pulse. the opti spark has nothing to do with wether or not the injectors fire unless there is no optical disc in it, the optical sensor is gone, or its unplugged.

tamatt27

Well guys, I hooked up the '96 PCM last night, and it cranked and tried to start. It would run, then die a few seconds after it started...like it was doing before I put the MAF on there. I thought the MAF fixed it, I guess it didn't.
Well then, I hooked up the '94 PCM (the one that came with the motor) and it did the same thing. Started then died. It did that a few times, then nothing. After it wouldn't start again, I check spark and injector ground at the same time, I had both, and it still wouldn't start this time! WTF?
Would an ignition switch cause an intermittent no injector ground and frequent dieing? It's a 3rd gen ignition switch BTW.
Welp Tristan, looks like Kitt's gonna miss the March 26 Thirdgen Gathering too!

TexasLT1

are you sure you put the opti on right? did it slide right on and fully seat with no force at all? sucks your not going to make it out. I'm going to austin for a couple days over break, I'll see if I can't stop by and give you a hand for a little while if you want me to

tamatt27

Yeah, I made that mistake on my old opti. I tried to slip it on by tightening the bolts. Needless to say, I went out and bought another opti, because I ****ed that one op, lol. But with the new opti, I took my time and it just slipped right in to place.
Oh I'm still coming to the gathering! I'll probably just have to bring the Suzuki (Old Blaze).
Sure, It'd be great if you could come by for a few hours or something. I'll buy ya lunch or something. I'm seriously thinking abouth having it towed to, either the dealership I work at, or to the shop of a friend of a friend....

Trans Am#5

Have you hooked up a fuel gauge to the rail to see what thats doing?
Also, who turned the VATS off in the PCM?