2.3L ('83-'97) 2.3l possible ICM/EGR issues need help

[mattlinebaugh13]

I’ve been trying to figure out my rough idle issues with my 1994 2.3l.
Some background info
I bought this truck for cheap after sitting at the deer lease for quite some time without running. when I towed the truck home and got it started, I had some rough idle and other issues that I eventually fixed. I bought an OBD1 reader and read the codes. Initially I got codes 335 and continuous code 224 along with some other codes that came and went. Ended up replacing the dpfe with a junkyard unit that seemed to work as the codes now read 111 with continuous 224 for KOEO test. Tried a KEOR test and immediately got fail code with 224 continuous. I went and got a junkyard ICM unit but would like to test the old unit before I replace with the new unit that may not even work since it’s a junk unit. My problem is I’m kind of an electrical dummy and can’t quite find a good answer on how to properly test the old ICM.
Also wondering if I clear the PCM of the 224 code will I be able to perform the KOER test?
the truck fires right up when cold and runs good until I drive for about 10 mins then turn it off for a few mins. After I crank it back up, it sometimes won’t start on the first turn and then it idles pretty rough for a couple mins then seems to smooth out when driving. I’m pretty stumped here and trying to see if anyone has had any similar issues. Thanks!

 

[mattlinebaugh13]

Figured I’d add repairs that have been made already (sorry I’m new)

new coils/plugs
Timing redone
DPFE replaced
Cleaned MAF
Cleaned IAC
NEW radiator / thermostat

 

[RonD]

Welcome to TRS

You may have all the OBD1 codes memorized but most don't, so good to include definitions with codes
224 (M) Failure in ignition coil primary circuit – Ignition Systems

Primary coil is the Passenger side(exhaust side) coil pack
Unplug the Drivers side(intake side) coil pack, the 3 wire connector
Start engine, if you can, and see how it runs
The 1989-2001 dual plug 2.3l/2.5l engines will run fine on just 4 spark plugs, just slightly less power, 2nd spark plugs add more power

The ICM(ignition control module) was used from 1989-1994 on the 2.3ls
They do fail, and often its heat related, which fits with your issue on Re-Start when warm
You can test them, but the problem is they can test OK cold, because the problem is heat related, its much the same for coils
You can't test if an ICM(or coil) is Good because of this

You could warm up the engine then shut it off, try to restart, if it doesn't then pour some water on ICM and then wait a few seconds for it to cool
Then see if it restarts

Just a heads up, the ICM needs heat sink grease on the back side when remounting it, for cooling
The 3 screws/bolts that hold ICM to lower intake can get rusty so hard to remove, and they are the GROUNDS for the ICM so need to be good grounds

 

[mattlinebaugh13]

Okay I will do the test when I get home. If it starts fine after pouring water on it the it’s probably safe to say that means the ICM is probably going out?
Hopefully I can pinpoint the issue with this “test” thanks for the input!

 

[RonD]

Yes, if cool ICM works, hot ICM doesn't, replace ICM