DIS Speculation

dimarra

Registered User
Well, I just had a DIS failure. (Why do these things have to happen at absurd times.)

When I took the old DIS off the car, the heat sink compound had dried up. Is this normal? Could it be part of the reason the modules fail? ...due to a heat build-up because the compound breaks down?

Would it be a good idea to put fresh compound at each plug change or some such interval?

...or am I just being overly anal?

Keith
 
dimarra said:
Well, I just had a DIS failure. (Why do these things have to happen at absurd times.)

When I took the old DIS off the car, the heat sink compound had dried up. Is this normal? Could it be part of the reason the modules fail? ...due to a heat build-up because the compound breaks down?

Would it be a good idea to put fresh compound at each plug change or some such interval?

...or am I just being overly anal?

Keith

You're on the right track Keith. Heat is what causes the DIS module to fail. Being a microprocessor it generates it's own heat and being in a hot environment it is essential that it's heat be dissipated. The way Ford did it was to use the mass of the accessory bracket as a heat sink, but for it to be efficient, contact with the DIS must be maintained for heat to transfer. How often you should renew the heat sink compound depends on the weather and other possible factors (how hard you drive, etc). I live in Arizona and I renew the compound every spring on mine. Make sure you use heatsink compound and not ordinary dialectric grease. John
 
what are some problems that could arise from the heatsink drying up and causing the DIS to go bad?

I heard that a bad DIS won't throw a trouble code as well, is that true?


David
 
NCredSC said:
what are some problems that could arise from the heatsink drying up and causing the DIS to go bad?

I heard that a bad DIS won't throw a trouble code as well, is that true?


David

I have been through DIS module problems twice with my 90 in the last 100,000 miles (car has 158,000 now). Each time the car would barely run, and sometimes I couldn't keep it running at all. Usually after shutting the car off and waiting for about 30 min it would run perfect until it happened the next time. The car would lurch and buck have no power and miss like it was on 4 cyl, which it actually was. May or may not throw a code, but if a code is shown it probably will be "coil circuit failure", I don't recall the code #. John
 
That's the problem I'm having. So far got a code 48- coil pack circuit failure. I was using the flashing CEL to get codes, but they are hard to read. I'm getting a scanner (digital readout) tomorrow. Is it more likely to be the DIS instead of the coil pack if that code comes up?

I don't mind replacing both, but just the one that is causing the problem would be nice.

Thanks for the help.

David
 
David - "coil pack circuit failure" codes are typical for a DIS failure, along with an engine miss, that makes it near impossible to drive the car. It doesn't entirely rule out a bad coil pack or leads though; so it's worth checking each of the 3 coil circuits (Haynes manual has a simple test proceedure for that). I did it on mine and it was finally the DIS that was bad; but at $200+ each it's worth trying to eliminate other likely problems first. I also used Radio Shack's heat sink grease, for about $2 tube - ok so far and thats a couple of years ago. Make sure you apply an even coating of grease - best way to do that is to use a grid of grease dots about 1/8" apart.


NCredSC said:
That's the problem I'm having. So far got a code 48- coil pack circuit failure. I was using the flashing CEL to get codes, but they are hard to read. I'm getting a scanner (digital readout) tomorrow. Is it more likely to be the DIS instead of the coil pack if that code comes up?

I don't mind replacing both, but just the one that is causing the problem would be nice.

Thanks for the help.

David
 
Yeah Jim, it's missing and almost impossible to drive like it is. I was thinking coil pack since I got that code 48, but I know a problem can cause a code that might not be the problem itself. I can get the a product called "Artic Silver" I think, at a place local to me. I read it was perfect for this heatsink type of application.

I'll know more after I do a complete code scan. Thanks for the help.


David
 
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I guess you could try new grease and make sure the screws are tight (one of which is the important ground). But once you've checked the coil pack (Haynes manual not necessarily the greatest, but for $15 it's saved my a... a number of times) and it's ok, then you've pretty much got to replace the DIS.
You might also want to do a search on DIS topics (on this forum), because I see some people got them for under $200. I paid like $214 with discount from Ford when mine went bad.
Good luck.







NCredSC said:
Yeah Jim, it's missing and almost impossible to drive like it is. I was thinking coil pack since I got that code 48, but I know a problem can cause a code that might not be the problem itself. I can get the a product called "Artic Blue" I think, at a place local to me. I read it was perfect for this heatsink type of application.

I'll know more after I do a complete code scan. Thanks for the help.


David
 
hmmmm?????

Just got through doing the test for codes with my new reader. Got 538 and 137. On the cylinder balance test, I got a 40, 50 & 60.

It had been hard to start before this problem happened and losing power. The plugs and wires were new in January when I did the HGs. We were thinking the injectors were causing the previous problem, so could they be messed up enough to be causing this?

I'm supposed to be getting some cleaned, flowed & balanced, but the guy hasn't finished them yet. It might be as soon as a week, but it could be longer too. I'd rather replace them first due to the codes I got than start replacing other parts. And I think the 538 and 137 might be caused by the problem, rather than being the problem.


David
 
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