88 Ranger bad ecm?

[Kenneth S]

I'm working on a friends 88 Ranger with a 2.9, and a 5 speed, it was sitting for a few years, and he changed out a few things to get it running.

New:
Fuel tank.
In tank pump, and sock.
High pressure pump, and filter (blew out the fuel lines).
Fuel pressure regulator.
IAC.
TFI module.

It was running fine for about a year then it suddenly decided to die out (hot, or cold didn't matter) it would start right back up, but it would cut out, and back fire in the intake. I pulled the codes and got a PIP, and O2 sensor code, so I replaced the TFI module, the pickup in the distributor, and the O2 sensor then cleared the codes. Now I have no codes, but it still dies out, and acts up same as before only it does it after it's been run awhile. One thing I noticed is that the ECM gets so hot that you can probably get burned if you touched it. I don't know much about these ECM controled engines (just enough to be dangerous), but it shouldn't get that hot should it?, and would that be part of the problem?

 

[RonD]

ECM should not get that hot, I would pull it out and inspect it for burnt or discolored wires and contacts.

The ECM relies on many sensors that use resistance/voltage as the data, so extra heat in the ECM would effect the ECMs interpretation of that data.

 

[ashleyroachclip]

The ecm should never get hot.
Replace it with a known good one, but while you have it out , inspect all of the wires, pins and sensors, for shorts or intermittent opens .
Also make certain you have all of the grounds , clean and tight.
When I say all grounds , there are more than just the battery ground .
There is a ground @ the ecm , cylinder head to firewall , block to frame rail , just to name a few.
The more the better.

 

[Kenneth S]

Everything looks good as far as the wiring goes, no burnt wires that I could see (but I'll pull the ecm to make sure, it was too hot to pull it at the time). All the grounds are in place, and clean. Apart from the parts I listed, the truck has been pretty much un-touched "modified".

 

[Kenneth S]

Well, everything checked out good, put in a different ecm that is known to be good, still does the exact same thing (also no codes). MAP sensor maybe?

 

[ashleyroachclip]

Is the ecm still getting hot?

 

[RonD]

A bad MAP will generally set a code, the MAP also only controls air/fuel mix to a point, so a stall out doesn't seem likely, especially if it restarts easily.
Running rich and lean, rough running and rough idle would be more related to bad MAP sensor.

The Crank Position sensor(CKP) turns on the spark, this sensor is how the computer knows the crank is turning and that it should turn on ignition and fuel.
If sensor stops sending pulses the computer would turn off the ignition system.
Restart would work if sensor or wiring for it was intermittent.

This would only set a code if there was a no start, i.e. start motor is turning but computer is not receiving pulses from the CKP.

 

[Kenneth S]

The ecm get warm, but not hot like the one that was in it. The truck will sometimes starts back up easy, and sometimes it won't, when it starts back up (easy, or hard) it has a hard time staying running. Sometimes when it acts up it runs bad for along time, and sometimes it will run just fine just after a few seconds, it's pretty unpredictable. This one does not have a cps (I put a new pickup coil in the distributor along with a new tfi module).