Ignition Control Module

[BMWburner]

Greetings, men:

I'm going to replace my ICM. I assume you just unbolt it from the cylinder head, swap the coil packs, bolt the new one on, and replace the data, and plug wires. But I often assume the worst so I figured I would check the ol' forums.

Anybody done this before? There wasn't much in past threads about ICM replacement, at least not in the do it yourself field, so any input would be apreciated.

As always, thanks in advance,

--Ben

[Ranger]

Yeah, quite easy. 2 bolts on each coil. 2 plugs on each side. 4 bolts mounting the ICM. On mine ('97) 2 of the 4 mounting bolts are hidden on the back side. I had to use the Braile method to remove and install those.

[WarrenJ]

I'm going to replace my ICM . . . . But I often assume the worst so I figured I would check the ol' forums . . . . (wise move, there) . . . . There wasn't much in past threads about ICM replacement, at least not in the do it yourself field, so any input would be apreciated.

As always, thanks in advance,

--Ben

Okay, but mind telling us why?

Regards,

Warren

[Scotty]

Warren toward the end of this thread Ben decides to change his module, Mike

http://caddyinfo.ipbhost.com/index.php?showtopic=7217&hl=

[BMWburner]

I had an interesting day today. Yesterday I replaced my ICM. This was done in a effort to remedy extremely poor power, uneven combustion, and inconsistent idle speed, and the enigine's inability to reduce it's idle speed properly when the VCC is disengaged. (Like when costing down an on ramp, the engine maintains 1500 RPM under NO throttle and slowly drops to idle speed) It still "barks-up" to 1500 RPM or so when started regardless of temperature, then settles down after a few seconds. The mentioned symptoms diminished some what after the ICM replacement but remain prominent. The only code I ever received on the matter was PO23.

I was also still receiving poor fuel economy (15 MPG mixed). I tried a series of WOT's to clean out the carbon from the poor combustion, but decided that an 3 intake regiment would likely be the way to go considering that the car was driven for darn near two weeks before I got the ICM from GMparts direct.

Now let me start off by saying that I have had great luck with these 3M products, they typically offer little harm to any engine, this is pro caliber stuff. It's basically carb cleaner, a fuel additive, and most importantly an aerosol that is sprayed into the intake under moderate throttle to cleanse carbon deposits. This stuff really works.

I'd have done it myself but I have no time this week, so I took to my college buddy who's an oil jockey at an express lube. We cleaned the throttle plate, it didn't need much as I just cleaned it myself. We started the aerosol spray with the engine revving at 2000RPM. No problem. When we shut the engine down. BAM, coolant starts pouring out of the coolant cap. Once the car cooled down everything appeared to be fine. The coolant was replaced less than 5000 miles ago before I bought the car, it's still bright green. It was done by a private mechanic...perhaps didn't know what he was doing. What the hell happened? Was it in limp mode while the intake conditioner was spraying into the engine? Why didn't it overheat until the engine was shut off? It didn't show any messages on the DIC until after the car was shut off. There has been no damage that I can tell and the power and fuel economy has been restored in spades.

After the overheating incident, I was on the highway and the engine stumbled and again I received the dreaded PO23 code again. I wouldn't be surprised if I cooked my brand new ICM when my N* overheated. Then again the new ICM didn't solve all my problems so I'm about to give up.

I've replaced:

Plugs, and plug wires. My mechanic

ICM Myself

Cleaned throttle plate and body....you could eat off it. Myself.

What’s left to check?

PCM, coil packs? How much of the ignition system is left to replace? How can I check the ICM with a meter to check it's condition?

Please help, I'm almost broke. I’ve pissed almost 700 bucks away here, not cool.

Thanks,

--Ben

[Scotty]

EST = Electronic Spark Timing

I only have a 91 and 96 manual neither of which can help here.

You need to 1) read up on the EST section of the manual, and 2) find CODE E023 in the manual and do the diagnostic.

Stop replacing parts without a definitive symptom or test result. First I would look at the routing of my ignition wires to ensure they are routed properly then attack the E023 diagnosis in the manual..

As far as it boiling over, GREEN means NADA! Get a coolant tester and check your coolant concentration, my guess is that you have less than a 50/50 mix and you are boiling at a lower temp OR your cap is bad not providing 16 pounds of pressure and allowing it to boil at a lower temp. If both are OK, consider that your thermostat is sticking.