My car just died one day. I discovered that I did not have any spark. Since the coil, distributer, ignition module, and cap were very old, (bought the car 2 years ago) I replaced them all. The car started with all the new parts, but would only run for about 3 seconds then die. I disconnected the EST (tan n black) wire, and the car started with no problems. Set the timing to 6 deg btc (that came off the hood sticker). Turned the engine off, reconnected the EST wire, and the car still did the same thing, runs for a few seconds then dies. I then replaced the ecm and it still does the same thing. I've replaced all the ignition components plus the ecm and it still will not run. The only thing I have not replaced are the sensors and chip. Any suggestions. By the way, yes I do have a code 42 and I used the shop manual to trouble shoot this fail. The manual told me that the ecm or ignition module were bad.
Thanks,
Rudy

 

i'd check fuel pressure and volumn

 

I have not checked the fuel pressure. The engine revved up thru 3500 rpm with out any problems without the est cable hooked up after I timed it. But, I guess I can give it a try, thanks.

 

Do you have spark now? To all plugs? Is it nice and bright? If none of the plugs have spark, check the coil wire (assuming the coil has been replaced)....

Now wait a sec, just realizes it runs fine with the ESC disconnectedd, but not connected, right? You said you replaced the ECM, are you sure the new one is "good"?

Will both of them run the car with the ESC disconnected? Just trying to eliminate variables...

I think I've heard somewhere on these forums a bad MAF can cause these exact symptoms, are you MAF or MAP based? Being a '90 I'm guessing MAP sensor based.

Any chance you've got a buddy with a same setup (speed density vs. MAF) that you could try his memcal and see if that's the problem?

 

Yes the car runs the same with both ecms. Without the est wire connected the car will run all day. I have a map set up. I believe the MAF ones have the wire sensor in the intake, is that correct. I guess I can trouble shoot the map sensor to see what I am looking at. Thanks.

 

Yep, you've got a MAP/speed density (not MAF) system.

Any chance of getting a buddy's prom to try? (just to make sure the current one hasn't gone south)

I'd also look at the knock sensor and make sure it isn't grounded out against the exhaust.

And I'll try to think of some other ideas. Maybe one of the "gurus" will chime in,,,,,,

 

You eliminate the spark timing module by unplugging the wire (setting base timing) and the engine runs. You plug the wires back togther and the car doesn't run.

I suspect the spark timing module is bad.

IIRC, it's a flat box located on the firewall and has a flat 4-wire Weather Pack connector.

Edit: Spark timing module is in the ECM for your model year. My apologies.

 

Update:
I had a few extra minutes to spare so I was looking for loose connections and wiring problems. I saw a connector that seemed to be 3/4s off. I pulled it off and reinstalled it. I think it is the map module. Not really sure though. It sits on the back of the on the left side, just next to the back intake runners (this as you look at the engine from the front of the car). I looked at my haynes and it does not have a good picture. The shop manual does not have a good picture either. Anyhow, the car ran for about 5 minutes then it died again. Really strange. I am going to have to look at the circuit that involves this module what ever it is.

 

When you replaced the ig parts did you check the pickup coil in the dist..Also check the connector that goes into the ig mod (black box that sits under rotor ) there is a 2 prong connector with a plastic sheild connector.I f the plastic is broken or wires are exposed replace the pick up coil..About $12 at any car parts store.GL