Bad DIS . . . AGAIN!

[shomesomesho]

This is the 3rd time I've replaced the DIS in 6 months. It starts off as low end loss, a noticeable "miss", then increasingly becomes un-drivable. Replace the DIS and all is well again for a few weeks. Just replaced the DIS again today and we're back on the road . . . at least for awhile.

Is it this common for the DIS to fail? Is there a known fix or other issues I need to be aware of?

 

[gmorrell]

Maybe time for a new coil pack? Could be one of the coil primaries has some shorted turns and is slowly wiping the DIS module.

 

[Xs SHO 1]

Was heat sink compound used on the back of the DIS?

 

[shomesomesho]

Maybe time for a new coil pack? Could be one of the coil primaries has some shorted turns and is slowly wiping the DIS module.

Could be. Will an ATX coil pack work on a MTX SHO?

Was heat sink compound used on the back of the DIS?

It has it now..

 

[dpsutphin]

As mentioned by Xs SHO1, sounds like you may have used the wrong, or no compound on the back of the DIS. Use white heat sink compound on the back. It is the same stuff used between computer processors and heat sinks on the inside of your computer, thus the name. You can get it at any computer store.

If you are using used DIS modules as replacements, it is entirely possible to get three bad ones in a row. There are also several modules that look exactly the same, but are not exactly the same. You have to match up the part number with the original from your engine. Some are interchangable, some are not. And those that are not will work for a while, then fail, just as you are experiencing.

Hope this helps.

 

[shomesomesho]

The DIS modules I have are all used items. Some came off an ATX, some came off an MTX. My car is an MTX.

Is there a reference where I can find out which DIS part numbers are compatible with which years?

 

[Venom SHO s7]

As mentioned, I would think if there was no heat sink paste used between the DIS and intake mount are, the DIS could've fried itself.
Im not 100%sure if they are the same, but I have swapped DIS-es, from ATX to MTX with no problems.

Also, I've gotten my DIS checked at autozone for free.

 

[1slickRED89]

early DIS modules limit primary current to 5.5 amps while later units are 6 amps. this will not effect it's function in any way though.

I'd check all the grounding points too. maybe a 'wiggle test' on the crank sensor plug and cam sensor plug are in order as well, to check for weak connections due to corrosion.

 

[Rockledge]

Any Ford V6 DIS module will work on the SHO, as noted.

 

[shomesomesho]

Ok, I just replaced my coil pack today, using a new unit made by Wells from Autozone.

With the (used) replacement ATX DIS and fresh heat sink compound on the back, let's see how long this baby lasts

Runs pretty d@mn good so far.

I'll have AZ check my old DIS's as well. They do it for free, right?

 

[FoeSho]

So what exactly was your car doing before? I am trying to chase my problem down too. I have a misfire, but the plug wires are fine and I have no oil int eh plug wells. The plugs themseves look good too. My misfire seems to be worse the warmer it gets outside. The car runs fine with no load or at higher RPM's. Can the valves out of adjustement cause this at all? Or maybe its liek your car and the ignition module has gone bad.. is this a common problem in general?

 

[shomesomesho]

So what exactly was your car doing before? I am trying to chase my problem down too. I have a misfire, but the plug wires are fine and I have no oil int eh plug wells. The plugs themseves look good too. My misfire seems to be worse the warmer it gets outside. The car runs fine with no load or at higher RPM's. Can the valves out of adjustement cause this at all? Or maybe its liek your car and the ignition module has gone bad.. is this a common problem in general?

You pretty much describe what my car was doing with the bad DIS.

Runs fine when cold, but the hotter the engine got, I would notice first a low end loss, then a low end misfire, then frank sputterring and choking under 3000 rpm. Car for the most part ran OK at higher rpms.

 

[FoeSho]

wow, hmm maybe thats MY problem too!!

 

[FoeSho]

how do I test that to se if thats a problem. I have no codes.

 

[dpsutphin]

OK guys...I had the exact same problem a while back. Changed DIS modules, and got same symptoms again...just like y'all are getting. Car ran terrible until the secondaries kicked in, then it was as if nothing at all was wrong. And since it isn't practical to ride around town in second gear all day, I had to find the solution.

I did two things that fixed the problem, I just don't know for sure which one fixed it, but both are cheap and relatively easy to do.

First, if you have not already done so, follow all the wires from the DIS, and fuel injectors, especially where they contact anything metal. Use good quality electrical tape to cover anything that looks even remotely bare.

Second, replace your fuel filter. Misfiring can be from lack of fuel as well as electrical. I actually had to replace mine twice before the problem went away. I replaced it once, and it went away for a week, then came back. Replaced it again, and no problems since.

Good luck.

 

[FoeSho]

yeah see, my problem is ONLY intermittant and at lower engine speeds when "lugging" the engine. If I ease into the throttle, anything past 3000-3200RPM is fine, ontl get a miss every now and then above that RPM.

 

[Devin]

Does anyone know what the purpose for the TIM (thermal interface material) on the DIS is for? I wanted to know because there is quite a difference in quality with different kinds of TIMs.

 

[shomesomesho]

Does anyone know what the purpose for the TIM (thermal interface material) on the DIS is for? I wanted to know because there is quite a difference in quality with different kinds of TIMs.

you mean the heat sink compound?

 

[1slickRED89]

Does anyone know what the purpose for the TIM

to conduct heat out of the DIS into the crossover tube. the module has some heavy duty electronics that sink heat into the metal back plate and (with grease) into the intake tube.

any cheap zinc-oxide based grease will be OK. just so long as it's there and the two surfaces have good contact.

 

[Rockledge]

Does anyone know what the purpose for the TIM (thermal interface material) on the DIS is for? I wanted to know because there is quite a difference in quality with different kinds of TIMs.

The subject was discusssed pretty good in this thread:

http://www.shoforum.com/showthread.php?t=58423

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