Shutting off during Hot weather

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#1
Make
Chevrolet
Model
Celebrity
Year
1989
Miles
338,301.7
Engine
2.8 V6
My Celebrity was back to shutting down during periods of high heat(75 an over). would this be caused by a faulty MAP sensor
 
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#2
Heat can cause all kinds of electronic devices to malfunction. You have the old OBD-1 system on that car. Is the check engine light on? Do you have any codes?
 

billr

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#3
Will it crank and re-start immediately, or do you have to wait for a while to re-start? How long do you have to wait?
 
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#4
Heat can cause all kinds of electronic devices to malfunction. You have the old OBD-1 system on that car. Is the check engine light on? Do you have any codes?
Heat can cause all kinds of electronic devices to malfunction. You have the old OBD-1 system on that car. Is the check engine light on? Do you have any codes?
I did find out that was a tech bulletin for My Celebrity that was not done i.e. moving the MAP sensor from the back of the engine(extreme heat) to the far right side of the firewall. work in progress-I'll do this evening after it cools off outside. When finished will check for codes.
 

nickb2

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#5
These had the three coil pack system with the famous ignition control module that would do just that, quit during high heat.

If you can find out what quits first when it stall, that would help. Does the spark quit or the fuel? I found that using thermal paste, much like a cpu in a PC would help these ICM's from overheating and shutting down.

There used to be discussion among older techs which stuff was best to use, di-electric grease or the AC delco compound. I found the grease lasted longer but not as efficient in cooling. Where as the AC delco grease/compound would crust and flake faster hence also loosing the heat dissipation factor also. So it became a habit of mine to remove the ICM every time I did a spark plug swap or wire swap and clean it up and apply the delco paste or di-electric silicone grease. IMO, both where better than none at all.

You should have a shield mounted between the coils and the ICM, that is a good place to apply the heat dissipation grease. Yopu will see the heat sink very clearly once the shield is removed. It will be below the 2 coil packs next to the two PCM to ICM connectors of the ICM once the shield is removed.

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nickb2

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#6
Another thing to consider, magnets and heat. The worst enemy of a magnet is heat. this affected the crank sensor alot in those years, and as they would get older, they would get weaker and heat was also a contributing factor to quitting in high heat situations. Also, there were problems with oil getting into the connector and making a bad contact, but that had nothing to do with a heat related problem. It also didn't help that it was located right behind the rear exhaust manifold. Prime location for a huge amount of heat.

Often changing an ICM and a crank sensor was a good preventative measure as they age the same way. It was part of our daily duties back then. Nowdays, in modern cars, we have different systems, but very much the same problems, now it's the COP (coil on plugs) that quit individually, much like light bulbs in your house. When you start changing one out, sure enough, another light bulb will quit soon enough.
 
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nickb2

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#7
I know alot will say it is not necessary to install some thermal paste, but I highly recommend it. I have been doing this for 27 or mores yrs now as a pro and highly recommend it. At least some sort of silicone grease.

If your on a dime, just go to a local computer store and buy some CPU compound in a small tube. They sell that cheap so you don't have to buy the 30$ di-electric grease tube. A small amount goes a long way in getting more miles out of an ICM, especially if installing an aftermarket one, or even worse, a used on.

80% of the times when these gm engines die in high heat situations, start back up after a quick cool down, suspect bad ICM and/or crank sensor. Nothing else really gives out like that, never really heard of a MAP only quitting in high heat situations. There are no transistors in that type of sensor, no magnet to speak either.

Only in rare situations will you see a PCM do this, but that is not unheard of either.

But cheapest way, check to see if it is the TACH/spark that dies. Usually, ICM.
 
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#10
Will it crank and re-start immediately, or do you have to wait for a while to re-start? How long do you have to wait?
It's getting fuel @ 47 pounds as per the shop manual.So my guess was the coil packs heating up, and were dam hot after being shut down for 4 hrs. I pulled the pack and upon disassembly discovered there was not di-electric grease at all. I had another ICM and installed all of it together(coils an such). I took a tip for another guy and installed spacers under the ICM and the mount plate to hopefully dispense some heat. Will install all of this after it stops raining an see if this works,I had my doubts about spacers-what is your opinion?
 

nickb2

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#11
Air is a good insulator, I think Jacks hint about 1/4inch spacer is a good trick. I never tried on client cars, but I don't see how it could be a detriment at all.

Here is a picture of your setup. I am assuming he puts the spacers between part # 1 and #2 (ICM).

I put compound or grease between #1 and #2 (ICM) and #3 (heat shield) but spacers should also work. As jack said, permanent as no grease to dry out or crack from heat.

I haven't seen a car with this DIS system in years, maybe even a decade, in my bay. They all went to scrap yard. They did not last long in our climate. But they were great cars for the time and price. I had a pontiac tempest with same engine and drove that into a telephone pole. It was at 320k km's on it. It was my winter beater car. So no big loss on that one, but my back got hurt as I bent the 3 spoke steering wheel in half upon impact. Shock went straight to a lumbar spinal displacement. Floor was so rusted out, the front seat anchor bolts also ripped out of the floor pan.

Safe to say, the telephone pole was still upright. :eek: Me, not so much. Car went straight to scrap yard, it was a goner, but I got lucky, again!:cool: Screenshot (205).png