I went out to start the car the other day and it started fine. So i shut it off and burned another PROM (chip ) for it. Put it in and it wouldn't start. So I put the firts chip in it and it still won't start. I tried my ECM in my buddy's car and it works fine. I also tried his ECM in my car and it still won't start. I have spark, and I'm getting fuel pressure at the schrader valve. The fuel injectors also have 12v. with the key in the on position. I pulled a spark plug and it looks fouled. Is it possible that it's so fouled that the car won't start at all?

 

How did you verify your spark?

 

Remember the ecm grounds the injectors to fire so make sure your getting that grounding effect going on while cranking. IIRC when you first swapped the L98 in there you were having a no start because of ecm grounding. Being as that motor is new and the rest of the mechanicals are also in good condition I would heavily suspect the electrical system. Especially since it's one of those just stopped working all of a sudden without warning type things.

As for the spark plugs being to fouled to function properly I doubt it. The car wouldn't have just not started all of a sudden it would have ran rough for a while before hand.

just my .02

 

Cool Runner is correct. Also, if you find that your electrical system passes all of his inspection criteria, take a look at the ignition module. If that fails, it'll cause a no-start condition as well.

 

That's pretty much where I stand now. I'm looking at all of my grounds. Can someone tell me which one of the pins on the ECM connectors is responsible for the ground that fires the injectors? I verified the spark my pulling a plug wire off of the plug and putting a spare spark plug on the end and watching the tip for a spark.

 

The injectors are grounded into the ECM by the dark blue and green wires that you see on the injectors themselves. The ECM then grounds those circuits (among others) through one of the black wires that go to the chassis.

Do you have a wiring schematic? It'll tell you which pins are which. Very helpful in looking for these types of things.

 

I've got a service manual I'm going to check this weekend but I just thought that one of you guys would know off the top of your head. Plus my book is about to fall apart from being used so oftem because the car is always giving me problems

 

I just got out my schematic.

The injector grounds are located at terminals C11 and C12. Again they are the dark green and dark blue wires.

Main ECM grounds are located at D1 (black/white), D6 (black/white), and D7 (black/white). These should all be within 2 ohms of ground at the ECM connector. Anything more than that and you have a grounding issue. With your continuity tester, put one probe at the ECM connector and the other probe on the negative battery terminal. You should have less 2 ohms.

Also, check your fuses, particularly the ones going to the ECM- both battery power (from C16) and ignition (from A6).

 

Thank you much. Will go try it out this morning.:hail:

 

If the spark plugs are fouled they won't fire even if they are getting spark from the dist. Save yourself alot of time and put in new spark plugs. I've fixed several no-starts this way, trust me...

 

I did that yesterday and it fired right up. Now I just need to learn how to lean out the mixture with a new PROM and I'll be set. These new plugs are just going to foul like the last set.

 

I was looking at the engine setup in your signature, and to be honest, there's no reason that your engine should be running so rich. Even with my modified ZZ4, I can go back and run a 1990 stock PROM halfway decently. The computer can correct fuel quite a bit before you end up spitting black smoke out the exhaust. Some timing adjustments would help out in the power production, but that's not absolutely critical.

Having said that, I don't think burning a new PROM is going to solve the problem. Somewhere in your system there is a malfunctioning sensor or something. If you can get a hold of a scanner, that would be the best thing- it will tell you exactly what is happening.

Either that, you're getting oil into the cylinders. Are all of the plugs fouled, or only a few?

 

All of the plugs were fouled. I think one of my sensors is bad as well because the thing has a lopey, choppy idle. Especially bad considering it's only a ZZ4 cam. I don't have a scan tool so it's making it sorta difficult. Actually, it's making it extremely difficult. Do you burn your own PROMs?

 

Yes. But I have run the stock chip in there before with this set-up. On my scanner, I can see the computer making a pretty hefty correction on fuel, but it still is able to maintain a 14.7:1 AFR. Which is why I'm certain it's not a PROM issue with your car.

Try this:

Locate terminal E14 on the ECM. It's a purple wire and is the O2 sensor signal to the ECM. With a digital voltmeter, put one probe on that wire and the other one to the terminal next to it at E15- a tan wire (O2 sensor ground). Start the engine and watch the voltmeter. If normal, it will be bouncing around from .1V (lean) to .9V (rich). It means that the computer is correcting. In your case, I'd imagine that the values will be high- up between .6 and .9. If the value is stuck at one voltage, the O2 sensor is likely bad, or you have a faulty O2 wire on the vehicle, or a bad ground someplace.