ECM Questions

[e21pilot]

I've got a high mileage 92 4.0 V6 that generally runs well, good power, OK gas mileage etc. after replacing all the usual suspects. Only thing that bothers me is that it sometime accelerates a little rough and sometimes doesn't return to idle RPM very smoothly.

A lot of posts suggested a faulty ECM could be the problem. Wondering if it is best to by a new one, try some used ones, get it repaired etc.

 

[adsm08]

Electronic modules are generally either there or not. It is very very unusual for a module to cause an intermittent problem. I would suspect the IAC is at fault.

 

[e21pilot]

I replaced the IAC with a new OEM unit because I thought it could be the source of some idle problems. It did seem to smooth out the idle some once the rpms were stable. Unfortunately is still has the rough acceleration (compared to my other 4.0) which I why I am wondering what else it could be.

Any recommendations on a good source for refurbished ECUs?

 

[lbug7575]

It is very very unusual for a module to cause an intermittent problem.

 

[RonD]

Yes, I agree with the others, ECM wouldn't be your issue.

If you haven't already, clean the MAF sensor: http://www.therangerstation.com/tech_library/CleanMAF.shtml
Always been an issue with the 4.0ls, stumbling is a classic symptom of dirty MAF sensor

And a "refurbished" ECM would mean someone had wiped it off before selling it
There are new ones still available, not sure about remanufactured

If you think the ECM might be the issue pull it out(disconnect battery first) and make sure the connector and pins are clean and dry, moisture in this connection can cause intermittent issues.
Then remove the cover, warranty is a moot point after 23 years, lol
have a look here at a clean ECM: http://www.auto-diagnostics.info/ford_eec_iv

There will most likely be some discoloration from leaking capacitors