Constant icm failure due to exhaust (Page 1/2)
pontiacfierokid1985 JUL 24, 10:57 AM
Question for everyone is there a way to move the icm from out of the distributor. I have custom built headers when i bought my recent 86gt 2.8. Thing is im constantly going through modules since the exhaust cross over pipe literally is right next to the distributor. I heat wrapped that pipe to see if it will help but i dont want to chance when driving a icm failure. I was thinking of cutting a small slit in the cap and running the wires out to the trunk firewall and mounting the icm there so it is away from the exhaust. Has anyone done something think this? I really dont want to buy stock manifolds and cross over just to not blow icm’s
cvxjet JUL 24, 11:50 AM
First off, do you have the original heat shields in place that protect the Distributor from the crossover pipe? Second, only buy the AC/Delco ICM....I went thru a few "Masterpro" and "Standard" ICMs before someone told me not to bother and get the good one......

Believe it or not, you are not trying to "Keep the ICM cool"- That thing gets HOT all on it's own....What you are really trying to do is COOL off the ICM by not having too much heat in it's vicinity....Meaning, limit the exhaust heat radiating towards it. (Sounds the same but is actually different)

Some people have moved theirs, but I haven't had one go out since I installed the AC/Delco ICM.....I also carry a spare- it is the last non-AC/D that had not failed- It only has to get me home, and then I would order another AC/D (They are a little bit more expensive ($70-90)....I also carry a spare Coil and of course the tools to change them. I did move my coil to the trunk wall, and then added a heat shield to block the heat radiating from the exhaust towards it (Used a laser temp sensor, driving to work(30 miles) in the morning; In Original location it was 160*, new location was 120* )
pmbrunelle JUL 24, 12:28 PM
I doubt that the original heat shields would fit over the custom exhaust, but why don't you just make some heat shields for your exhaust?

Also, is your trunk blower fan operating and directing cool air to the distributor? If not, make it work... and consider bypassing its relay to be always on with the key in run.
fierofool JUL 24, 02:59 PM
Weak plugs, wires or ignition coil can also cause rapid failure of the ICM. Be sure the deflector shield is on the ignition coil that will help direct some air from the cooling tubes, when the AC is operating or whenever the cooling fan comes on.
Patrick JUL 24, 03:04 PM

quote
Originally posted by pontiacfierokid1985:

is there a way to move the icm from out of the distributor?



Ignition Module / Ignition Coil remote relocation by larryfiero
theogre JUL 24, 03:51 PM
Several people have remote mount the ICM... Use Search but some are likely better then others. Anything that Generates heat like ICM etc in the trunk can have similar problems w/ lack of air to cool and so on. Most forget the Trunk gets hot from weather, exhaust, etc, w/o putting it other things that dumps heat in there too. That's ignoring other crap, often heavy hard things, take space and gets dropped/thrown in a trunk that can damage it.

Many claim is a weak ICM that fails but several things can kill the ICM like an iffy coil, tach filter, cap and rotor, and even a crappy ICM mounting screw can kill it. Mounting screw Is The Ground for the ignition. Any Problems on high voltage side can kill it w/ spark you often can't see. "Performance"coils including MSD and Accel products won't help either.

Have the engine blower on all the time has problems too like the blower can die soon this way.

Heat shied(s) are a completely passive heat control that works very well but you need to understand how they do their job.
They mostly block IR light from the exhaust or whatever hot hitting on everything behind one.
So when you make one and not sure what to shield then use a small light in several spots and make your shield w/ a shadow to shade what you want to protect.
But watch the size and shape because may block air flow...
IOW You can't just shield the whole distributor because ICM won't get air flow w/ and w/o the engine blower on.

Exhaust wrap is often bad. May keep heat in but the pipes get way hotter then normal and can fail from stress for heat cycling or water gets in and attack the pipe.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

pmbrunelle JUL 24, 06:47 PM

quote
Originally posted by theogre:
Have the engine blower on all the time has problems too like the blower can die soon this way.



I thought about that, but I feel like blower on all the time is considered a normal operating condition, as it comes on every time the A/C is switched on.
I imagine that for folks in Texas and such, the A/C button is left permanently pushed in. Are their blowers dying often?

Personally I drove my previous Fiero for about 5 years / 50 000 km, blower on all the time, without a blower failure.

I prefer to favour the reliability of the distributor and ignition module by blowing air at them constantly, even if it risks prematurely killing the blower.

The blower fan isn't like fastback taillights; they aren't highly sought after, so replacements are easy to come by. For myself, a 5-year (maybe more, but that hasn't been tested) replacement interval for the blower is reasonable, considering that the blowers are plentiful and easy to replace in the car.
Patrick JUL 24, 07:05 PM

quote
Originally posted by pmbrunelle:

I prefer to favour the reliability of the distributor and ignition module by blowing air at them constantly, even if it risks prematurely killing the blower.



Anyone with an '88 doesn't have that option... without a whole lot of mods.

The heat sink I added appears to be doing the job just fine. My ICM is 12+ years old.
pmbrunelle JUL 24, 07:12 PM
Do the blower-related parts from the early Fieros not bolt into 1988 spaceframes?

Edit: For reference, OP's Fiero is an 86.

[This message has been edited by pmbrunelle (edited 07-24-2019).]

Patrick JUL 24, 08:01 PM

quote
Originally posted by pmbrunelle:

Do the blower-related parts from the early Fieros not bolt into 1988 spaceframes?



I can't swear to it (as it's been awhile since I looked), but I don't believe the 88's even have a hole in the trunk for the blower assembly.