Bad ecu?

madtom421 · Sep 1, 2018

1988, Been having some phantom electrical issues. Truck will run fine then randomly loose power and puff black smoke out the tail pipe, then run fine. Some times worse than others. No codes, pulled the ecu and took it apart and think I may have found my problem. There's also some corrosion. Ordered a new ecu off rockauto, hopefully this is the answer to my problems.

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ericbphoto · Sep 1, 2018

Some people have repaired that by replacing those blue capacitors. They don't cost much online. Sometimes just a few cents each. Just have to get some with the same number markings on them. Of course it takes a bit of soldering.

This message composed solely of recycled electrons. Go green!

madtom421 · Sep 1, 2018

There's corrosion and some of the traces on the board look bad as well. Water has definitely gotten into it. I'm sure I could of fixed it but a new reman ecu only cost $75 which seems reasonable to me. I just hope this is the cause of the issues I'm having. Bought this truck back in February and haven't driven more than to the store and back due to these issues.

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RonD · Sep 1, 2018

The 3 Blue capacitors start to leak electrolytes after 20+ years or so, you are at 30 years, not an uncommon problem, and most likely the cause of your issue.

Yes, they can be replaced, under $5 cost, example here: http://support.moates.net/capacitor-repair-ford-a9l-ecm/

All 3 should be replaced, even if only 1 is leaking "now", lol.

You can use no-residue alcohol, i.e. electronics cleaner, like MAF sensor cleaner, to clean up under the leaking Cap and other traces that show corrosion.

Getting a refurbish ECU is fine, they do the above so it should last another 20+ years

madtom421 · Sep 1, 2018

These are some of the other areas of concern I have that made me opt for a replacement. The trace looks damaged/ missing ( circle spot is worn thru), and whatever those small things are one looks to be cracked.

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RonD · Sep 1, 2018

That should clean up just fine.

Water doesn't cause shorts, the MINERALS(salts) in the water or on the surfaces cause the shorts and corrosion.

Remember the high school science class.............where you put two electrodes, hooked to a Light Bulb, in a glass of distilled water(no minerals) and plugged it in to power
It didn't light up
But if you sprinkled table salt in the distilled water the light bulb start to glow, the more salt you added the more electricity it passed between electrodes.

And you thought you would never use any of that stuff

madtom421 · Sep 1, 2018

It has spent 30 yrs in new England where we do salt the roads when it snows every year. New one ordered rather just rule it out completely. Thanks for the responses. As for high school science class thats just a distant memory of decades ago lol.

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madtom421 · Sep 10, 2018

No dice the new ecu has made the problem worse I swear. Runs fantastic for first 10 minutes then just starts puffing black smoke and power loss. I ordered a new o2 sensor, ignition control module, and complete tune up kit. This truck only has a pre cat o2 sensor but would having a hollowed out cat be a issue?

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RonD · Sep 10, 2018

Check the Fuel Pressure Regulator(FPR) on the engine.
It has the Return Fuel line attached and a smaller Vacuum hose
Pull off this vacuum hose and check it for fuel, gasoline smell

Cold engine NEEDS to run Rich, once it warms up it will run rough if still Rich, like running carb engine with full Choke, runs OK cold but not warm, lol.

If FPR was leaking a bit Vacuum hose would suck extra fuel into the intake, causing the Rich running

madtom421 · Sep 10, 2018

RonD said:
Check the Fuel Pressure Regulator(FPR) on the engine.
It has the Return Fuel line attached and a smaller Vacuum hose
Pull off this vacuum hose and check it for fuel, gasoline smell

Cold engine NEEDS to run Rich, once it warms up it will run rough if still Rich, like running carb engine with full Choke, runs OK cold but not warm, lol.

If FPR was leaking a bit Vacuum hose would suck extra fuel into the intake, causing the Rich running

I've read about this, fpr has been replaced only about a yr old. I'll check for fuel in the vacuum line. My brother read that if the temp sensor for the computer is bad it may also cause computer to run fat. My temp gauge broke and I have a aftermarket temp gauge I do notice when the thermostat open it drops to like 160 degrees. Could a incorrect stat be part of the problem?

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RonD · Sep 10, 2018

Should be running closer to 180deg after warm up but wouldn't make that much of a difference, computer should be running in Closed Loop around 150deg mark, so using the O2 sensor for air:fuel mix

Bad ecu?

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