Engine dies when warm

friend of a sc

Registered User
A friend of mine has an 89 supercoupe, and he's experiencing a strange problem. I've read thru many, many pages of this forum, and used your search feature...I've even spoken to an old friend that had a supercoupe a few years back, and so far this appears to be a new one....

His car starts up and idles fine, and drives as it normally should, until the engine reaches normal operating temps, at which point, whether driving or at idle, will just shut down. Here's the really tricky part...you cannot restart the car until it has cooled completely down...a 45 minute reset. After that, the car fires right up and goes on its merry way, until it reaches temp again, and the process repeats itself.

I've not personally gone to look at the car, nor am I very familiar with Ford's ( I specialize in a ...different... make of car), so I'm not positive on the specifics of what he's replaced and what he hasn't, but from what he's told me, he's already replaced most of the ignition components, including the ignition computer (?)...

No CEL or other indications appear...I'm pretty stumped on this one. Are there any auxilliary temp sensors that could be malfunctioning and forcing the complete cooldown reset, but don't give off any dash indication? Any other ideas? Anything at all would help at this point. Thank you for taking the time to read this, I apologize for being so long winded.
 
To me, that sounds like a bad D.I.S. Module. The DIS module is the grey thin rectangular box that sits towards the rear top part of the A/C compressor. It has two connectors and held down by four small screws. Either the heat sink compound dried out or the module needs replacing. In any case if it dried out, he is better of replacing it. Just my .02 cents. Hope this helps..
 
not the DIS...

I just spoke with my friend this morning, and relayed your idea. He said he tried replacing the DIS already with a brand new, fresh cold one while the car was dead on the side of the road, and it still wouldn't crank up until the car completely cooled. He's also replaced the ignition switch in the column and inspected the wires...that didn't fix it either.
 
A friend of mine has an 89 supercoupe, and he's experiencing a strange problem. I've read thru many, many pages of this forum, and used your search feature...I've even spoken to an old friend that had a supercoupe a few years back, and so far this appears to be a new one....

His car starts up and idles fine, and drives as it normally should, until the engine reaches normal operating temps, at which point, whether driving or at idle, will just shut down. Here's the really tricky part...you cannot restart the car until it has cooled completely down...a 45 minute reset. After that, the car fires right up and goes on its merry way, until it reaches temp again, and the process repeats itself.

I've not personally gone to look at the car, nor am I very familiar with Ford's ( I specialize in a ...different... make of car), so I'm not positive on the specifics of what he's replaced and what he hasn't, but from what he's told me, he's already replaced most of the ignition components, including the ignition computer (?)...

No CEL or other indications appear...I'm pretty stumped on this one. Are there any auxilliary temp sensors that could be malfunctioning and forcing the complete cooldown reset, but don't give off any dash indication? Any other ideas? Anything at all would help at this point. Thank you for taking the time to read this, I apologize for being so long winded.

May sound silly but check the make sure you have a bolt holding your balancer to the crank. I had a similar problem that resulted from the bolt not being present. Even had it towed to a garage for it wouldn't run and he let it idle for an hr and was like nothing is wrong. Went to take off and it was dead.

Let it cool down and it was good again...

-Tim
 
I just spoke with my friend this morning, and relayed your idea. He said he tried replacing the DIS already with a brand new, fresh cold one while the car was dead on the side of the road, and it still wouldn't crank up until the car completely cooled. He's also replaced the ignition switch in the column and inspected the wires...that didn't fix it either.

Also he may have replaced the DIS but did he put the Heat Sink Grease under it? Without that he would have the same troubles.

-Tim
 
May sound silly but check the make sure you have a bolt holding your balancer to the crank. I had a similar problem that resulted from the bolt not being present. Even had it towed to a garage for it wouldn't run and he let it idle for an hr and was like nothing is wrong. Went to take off and it was dead.

Let it cool down and it was good again...

-Tim

I'll have him look at that, thanks!
 
Also he may have replaced the DIS but did he put the Heat Sink Grease under it? Without that he would have the same troubles.

-Tim

He didn't, he just set the new one next to the old one and tested it by swapping the wires onto the new one and tried to crank it up while it was hot and it didn't fix the problem. Even without applying the heat sink compound, a fresh new "cold" DIS should have started the car if that was the problem, I would think...

I'll let him know about the bolt for the harmonic balancer and see if that's maybe the case....
 
My guess would be a bad EEC computer, but that's just a guess. Has he tried to pull error codes either before or during the problem?
 
he just set the new one next to the old one and tested it by swapping the wires onto the new one


If I am reading this correctly, this is not going to work... The DIS needs to be installed on the bracket with the small bolts in place to operate. The two bolts closest to the front of the car (with the DIS on the bracket) are the electrical grounds. If the DIS isn't grounded properly, it won't work.
I'm not saying the DIS is the problem, but not grounding it (or installing it without heatsink compound) is a definite problem.
 
I'm with Larry on this. If the DIS isn't installed properly, it's not going to function properly. He can get some Arctic Silver at Radio Shack and apply that before mounting the DIS and see if that works.
 
Make sure to tell ur friend to be generous when he applies the heat sink or arctic siliver. Whatever extra he puts in it, will come out on the sides when he tightens the module and then he can just clean that up.
Good Luck
:)
 
Another thing to check is the coil itself. I have seen some of them split underneath its mount and when they get hot no spark. Also when it wont start while cranking is there a upshift light on the dash lit only while cranking the engine?
If so the crank sensor might be going out.
 
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