New PCM, Car worked for month, now dead again

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Had starting issues with the 1992 Aerostar. The whole past story of it is here, but to make a long story short. We found the problem to be the PCM (ford calls it an ECM for Engine Control Module). Got one at (think it was O'Reilly) and had it installed and then the van worked fine for about 5 weeks. The starter died two weeks ago and we had it replaced, then last week it would not start. My shop is swamped with the holiday and a man on vacation so did not get a chance to try their spare PCM. They should be doing that today. They did find that the injectors were not getting a signal on cold start. We could start it with starting fluid and it would keep running and even restart without the starting fluid once running. But yesterday I could not get it to keep running at all, it would fire over and run until the starting fluid ran out. Dead as a doornail.

So, the question is, if he finds the new PCM went bad, should we

1. simply replace it under warranty
2. return it and buy one elsewhere of a different brand
3. figure that there could be something else wrong that will keep messing up every PCM we install

If 3, is there a way to figure that out besides blowing several PCMs in a row?

If I had not put about $1000 into this piece of junk I'd junk it now, but really at this point would like to get it back on the road and reliably.
 
FWIW, I recently had a problem with my Explorer not starting, which I eventually narrowed down to the computer. But, it turns out the computer was fine and it was the ECM relay that was bad. You can read about my problem HERE .
 
I'd give them one more shot at a PCM. I would also make sure there is no water leaking on the PCM and ruining it.
 
1.) It's not unheard of to install a part (especially a non-OEM) and have it fail right away. Just a junk part (poor quality)

or

2.) Something is frying the ECM and your part was fine, but something is causing it to fry.

I hope it's #1. If it's #2, the hassle of trying to figure out what's your frying your ECM in a POS van, is really not worth the expense, unless you're going to figure it out on your own.

I'd replace the ECM under warranty. That makes the best possible economical sense. If it blows again, go get another one (once again for free), but find the cause of your problem...or get rid of the van.
 
I would also look at the ect sensor if it thinks its super cold or hot it wont start. Also check the relays and ground circuits.
Can you hear the fuel pump run when you turn the key on??
 
Shop just called. It was the ECM. They are replacing it under warranty. He said there really is not way to test of something in the car is blowing the ECMs and noted that the part they got is a good brand, just that you can get bad ones every now and then.

I recall the time I got two bad Carter fuel pumps in a row and the shop finally went with a Motorcraft which is still performing fine now. So maybe I should have gotten a Motorcraft ECM?
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The Ford computer is most likely obsolete, especially of that vintage, so even if you were at my work we would go with NAPA or A1-Cardone. The PCM would be a Ford Genuine part, not a Motorcraft if available.
 
Ummm I wonder if the Areostar PCMs are failing because of leaking capacitors, seems to be a common issue in the early '90s F-series... I replaced caps in the one for my '93 Lightning and have repaired a second plus seen two that were burned beyond repair..

Lightningecm.jpg
 
Does your Aero have a diode in the starter solenoid switch that protects the components from voltage spikes? I'm pretty sure my '93 does. An air conditioner clutch relay can put spikes into the system whenever it cycles that can destroy electronic components. Since it is so cheap, replace the starter solenoid that is mounted on the fenderwell with a correct part. Perhaps the diode has failed and is allowing spikes.
 
Okay, I'll have them replace the starter solenoid. Funny, new starter and a week later the PCM is shot (Starter was different shop). Solenoid is cheap insurance.

As for replacing the Alternator, why? It is putting out 14.8 volts, the man tested it when he installed the starter. Alternator is not cheap insurance. If there is good reason though, then I'll consider it.

Thanks!
 
Originally Posted By: TallPaul
As for replacing the Alternator, why? It is putting out 14.8 volts, the man tested it when he installed the starter. Alternator is not cheap insurance. If there is good reason though, then I'll consider it.

As far as the alternator goes, it's worth checking the voltage at higher RPMs, say 3000 or so, as well. An alternator that overvolts at higher RPMs can cause problems and it only takes a moment to find out.
 
Cant say much I know about fords.

I replaced a '89 dodge "ECM" and the reconditioned Cardone ECM said that All sensors must be tested to be in the proper resistance range and all solenoids in the transmission checked before installing the new ECM or the warranty would be voided.

They said that the transmission solenoids or the wiring leading to them is the main cause of failure of ECM's. I don't know if this was for Dodge remans, my specific reman or a generic statement.

Before I ordered a new ECM I cleaned and inspected every single freaking wire on the van and did throw about 100$ in parts at it in blind hope.

I found a wire leading to the transmission was chafing on the bell housing in the slip stream and shorting out. I replaced that length of wire then bought the new ECM. That was in 05

within a year I started getting a code 53 saying internal computer problem detected.

Still have same computer, still same code. Still runs fine.

I think the alternator comment was to see if some AC ripple from a burnt Diode is getting into the system frying the ECM. One can always put their voltmeter on AC to check, if one can get the engine started.
 
So alternator, AC, and starter solenoid are potential problems. I don't think the tranny would be an issue. I think it is an A4LD and as far as I know it is not electronic in any way. The shifting is vacuum modulated. But wouldn't there be a protection device on or in the input to the ECM?

Oh, and my ECM never threw codes, neither the first time or this time.
 
Converter lockup and O/D is PCM controlled on A4LD, other functions are controlled by throttle cable and internal governor...
 
Originally Posted By: wrcsixeight
...I think the alternator comment was to see if some AC ripple from a burnt Diode is getting into the system frying the ECM. One can always put their voltmeter on AC to check, if one can get the engine started.


Yes, that was my reasoning. I have seen alternators do this often. Plays havoc with radios and small bulbs.
 
Originally Posted By: exranger06
FWIW, I recently had a problem with my Explorer not starting, which I eventually narrowed down to the computer. But, it turns out the computer was fine and it was the ECM relay that was bad. You can read about my problem HERE .

The thing is, he put a used ECM he had laying around, thinks was from an Aerostar, in it and it started every time. So it Would not be the ECM relay.
 
Yup. No way for it to be an ECM relay.

Ford ECMs are tough, seriously tough. I replaced three of them, one bad ECM off the transport at the dealership, one due to water intrusion, and one fried due to a lightning strike (which also fried another $3K worth of modules/electronics).

Everything the ECM controls is through grounds. Injectors- ECM grounds each injector individually (SEFI) or by bank. There is not really anything in the wire harness or injectors that can kill all the injector drivers. The fault is internal to the PCM in the logic somewhere. Could be a bad cap or just some microprocessor that decided to give up the ghost.

Ford assumes owners are stupid. Sometimes jumper cables get hooked up backwards- ECMs have diodes on their power inputs just for this. Voltage spikes happen, like from cheap non spec starter solenoids, alternator diodes fail (AC voltage output), but nothing that will kill an ECM.

More than likely the rebuilt ECM was garbage. When I was an independent we replaced our share of GM ECMs and sometimes we went through two replacements until we got one that worked properly. There are rebuilders that do very shoddy work. We learned fast to grab our ECM/PCMs from NAPA at that time.
 
Originally Posted By: TallPaul
Originally Posted By: exranger06
FWIW, I recently had a problem with my Explorer not starting, which I eventually narrowed down to the computer. But, it turns out the computer was fine and it was the ECM relay that was bad. You can read about my problem HERE .

The thing is, he put a used ECM he had laying around, thinks was from an Aerostar, in it and it started every time. So it Would not be the ECM relay.

The problem on the Explorer was very intermittent. It would sometimes go a few weeks starting no problem every time, and 2 weeks later, no start. I would replace a part, and it would start right up and I would think, "OK all fixed now!" Then 2 weeks later, same problem "OK guess that wasn't it afterall." Just sayin.
 
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