1990 CV Wagon Cranks but No Start

[gadget73]

I'm curious now.....how do you go about checking to see if an ECM is good or bad?
(other than swapping in a different one to see if it fixes the problem)

no real means to test it short of swapping it. You can probe a few spots to verify a few voltages, but thats about all most people can do. I suppose if you had some way of simulating the various inputs, you could monitor the outputs to see if they respond properly but I don't know too many people who have the means to do that.

[Freshmeat]

New plugs, cap, rotor, distributor, and battery cables later, I still have no start. I even cleaned the connectors for the injector harness.

It very briefly ran for a couple of seconds but it was more of a stumble and died quickly. I spent half an hour looking through my garage again for the old 89 ECM but no luck. Next step I can imagine is to tear down to the timing chain. Not at all looking forward to it, but it's all I can think of from here.

[85crownHPP]

Did you double check the ECM ground at the battery?

[marquisman]

i was gonna ask this as well, i got a 94 merc sable once for free cause it just quit on my buddy. he tried everything then gave up. with a little time with the volt meter i found the power wire was fucked and intermitenly gave some juice. it ran like a watch with a new wire

[Freshmeat]

Did you double check the ECM ground at the battery?

is that the one that has the little connector you have to squeeze to separate? If so, it's reconnected to the battery on the new cable. If not, I need more info.

[85crownHPP]

Yeah that sounds like it. Did you eliminate that factory squeeze connector? One of mine was all kinds of nasty inside it.

[Freshmeat]

I didn't eliminate the connector- it appeared clean, but if it's known to cause trouble I'll cut it out to be on the safe side. Not like the connector serves any reasonable purpose when everything else on the cable is permanent.

[Pirate]

You know, I'm vaguely recalling a ground wire or something that disabled the car if it was disconnected....and I'm also recalling having trouble with this wire once....I think it was on wagon #5 or #6....

[Freshmeat]

You better start recalling better fast! Haha! I'm straight up out of ideas.
When you say it disabled the car, how badly was it disabled? It's firing on some cylinders which tells me some things are working some times...

[Pirate]

You better start recalling better fast! Haha! I'm straight up out of ideas.
When you say it disabled the car, how badly was it disabled? It's firing on some cylinders which tells me some things are working some times...

As in the car won't run at all.

The one wagon, however, was running like bleeaggh, and it was traced down to this one wire fairly quickly, as I had been having trouble with the battery terminals on this car.

Please recall that this was around 7-9 years ago.....

It could be on the positive side, or the negative side, I don't have a Box out front to go run and check on. But for some reason, I recall it being on the negative side....

Did you double check the ECM ground at the battery?

Upon further retrospect (and forgetting that he already pointed this out, whoops), I think it's this very wire that Pete is speaking of here.

[Freshmeat]

Well, this has brand new cables on both sides and I reconnected that wire. I'll delete the connector and see if it helps any. I may pull an ECM at the yard just to see if it helps, but I'm not thinking that's the issue.

[91waggin]

Again I say MAP....when mine went, I would start it, it would fire on a few cylinders and then die. It was very frustrating.

[Freshmeat]

Is there a way to test the MAP without buying a new one to replace it?

I'm going to thoroughly go over all grounds again Tuesday afternoon to see if I find anything missing or in bad shape.

The local Mustang shop says there's a ground (supposed to be) bolted to the back of the intake for the injector harness that's known to rot out. I'll check that and if I don't get anything he said he has a 89 CV from which I can rob the ECM and see if it helps any. It's time to get this thing going!!

[Pirate]

Again I say MAP....when mine went, I would start it, it would fire on a few cylinders and then die. It was very frustrating.

My experience with bad MAPS sensors has been excessive, full-rich situations that drown out the motor, and will occasionally even puke out a bit of black smoke.

This is an electrical issue associated with the ECM, methinks.

[85crownHPP]

Did you check the 'salt and pepper' connectors? I've heard of them corroding their pins out too. These are the ones next to the TB that have the wires for all the injectors and sensors. I don't think the coil wiring is part of it but I may be mistaken.