ICM Problems and real solutions

[Joelzme]

91 2.3l 2wd

I have had to replace the ICM on this vehicle twice. Recently she has been running bad, replaced the PCV, spark plugs and wires, cleaned out EGR, etc, still no relief. Took to Autozone and the ICM is bad, again. They replaced for free.

I have exposed all the plugs wires around the ICM to look for chaffing or split wires. Nothing. I cleaned the wiring harness where it plugs into the ICM with electrical contact cleaner and greased with dielectric grease. She is bolted to the intake manifold securely with 3 small bolts (there is no 4th bolt receiving hole on my manifold for it).

I have heard that over time heat will break these down, but that area of the truck is not that hot. There have been issues with this same type of circuitry breaking down when attached to the distributor. This is the 2nd new one (Duralast) in the past 4 months.

Any information that you guys might have about the problem, or what worked for you to get rid of it would be really appreciated, no matter how small.

Joel

 

[BobbyB2300]

The lone lower bolt on the left side is the ground for the ICU. I ran a ground wire direclty to my battery(negative) from this bolt and had a 90% improvement. When the ICU faults, the computer resets to the default values as if you disconnected/reconnected the battery. This causes the engine to run rough. On my list is to cleanup the negative engine ground from battery to block. The ground on these modules is very unforgiving, not to be taken for granted. The ICU backplate is not a ground, it's a heat shield. The white putty you saw is an insulator for disappating the heat.

I also notice the EGR systems are prone to fail, many times its the DPFE compenent. You might want to clean your MAF sensor with MAF Cleaner, use the whole can with emphisis on the center hole.

Keep us posted, good luck.

 

[Joelzme]

Thanks for the info. I have replaced the DPFE sensor, which did clean out some codes and got my EGR working again, but my problems did not stop until I replaced the ICM. When you replaced you ICM and ran the ground wire did it stop you from having to replace it a lot? My goal is to not replace it all the time.

 

[Sevensecondsuv]

The next time it breaks go get your self the real Ford part. Supposedly the Motorcraft module lasts much longer than the knock-offs. Knock off stuff is just fine in 95% of the applications, but this is one area where there is supposed to be a big difference.

FWIW, my stock Motorcraft module is working perfectly after 18 years and 250,000 miles.

 

[BobbyB2300]

Thanks for the info. I have replaced the DPFE sensor, which did clean out some codes and got my EGR working again, but my problems did not stop until I replaced the ICM. When you replaced you ICM and ran the ground wire did it stop you from having to replace it a lot? My goal is to not replace it all the time.

In hindsight, I realize now my original stock Motocraft ICM was/is still good. The Niehoff replacement work fine, if it fails, I'll put the Motorcraft back in. My problem was a ground fault. My understanding is that ICM rarely fail and when they do, the car wont start. Question is then, does a faulty ground have the potential to fail the module, this I don't know. My amatuer understanding of electronics inclines to believe it's possible. Without a ground path I believe there is a possibiliy of a spike or overvoltage unable to disappate. Maybe someone with a better understanding of the voltage flow will chime in here.

 

[Joelzme]

In hindsight, I realize now my original stock Motocraft ICM was/is still good. The Niehoff replacement work fine, if it fails, I'll put the Motorcraft back in. My problem was a ground fault. My understanding is that ICM rarely fail and when they do, the car wont start. Question is then, does a faulty ground have the potential to fail the module, this I don't know. My amatuer understanding of electronics inclines to believe it's possible. Without a ground path I believe there is a possibiliy of a spike or overvoltage unable to disappate. Maybe someone with a better understanding of the voltage flow will chime in here.

I hope so too. In my experience with 2 of them failing, they have a fail safe mode where the ignition switches to a set timing and it just runs really rough. Thats about all the warning you get, I got once one failure a code showing the coil pack failed. I replaced that and the code still returned until I replaced the ICM. I will keep swapping the Autozone components if I need to until they will not let me anymore and then go to motorcraft.

My 91 is now my daily driver since it kills me to fill up my F350. She has 150k on her and is a rust bucket, but she's the first vehicle I have had to learn anything about. I have learned a lot about engines and parts so far so it's a good thing. Going to tackle resurrecting the AC from the dead next if this ignition thing works out.

If anyone knows about the specifics of the internal electronics of these parts it would be great if you chimed in. Specifically the differences between the OEM and non oem parts.

Thanks,
Joel