Check Engine light/ Misfire**pulled codes-Translation?**(post#5)

[USHOMEISHOU]

CEL is coming on and the engine feels like it's running on 4 cyls, light goes out and engine runs fine.

the car did this to me a couple of weeks ago and hasn't done it again... until today. (even made a 400 mile round trip to the lake this past weekend with no problems)

I'm at work all night and can't run the codes until tomorrow.

any thoughts? I'm thinking Cam Position Sensor

 

[AREA 91]

Feels like it's running on 4 cylinder's? That's not the cam sensor. I would start with the ignition system.
Plugs and wires

 

[hawkeye18]

Cam sensors aren't generally intermittent like that... either they work, or they don't work.

I'm gonna put my money on the MAF. Bad plugs/wires won't usually throw a CEL. MAFs will throw a CEL and make the engine run bad. If your fuel pump is intermittently (god I hate typing that word) crapping out, it might throw a CEL too.

 

[USHOMEISHOU]

Come to think of it, my fuel pump has been noisy lately (grumbling under the back seat for a few seconds after startup)

 

[projectSHO89]

Since the CEL was on, PULL YOUR CODES!

Did you,by chance, notice a 1/3 drop in the tach reading when the fault episode occurred? If so, you lost two cylinders, a problem often associated with a DIS module failure.

Too many variables at this point to replace any parts. You need to do more detective work first to avoid wasting money and time.

Steve

 

[USHOMEISHOU]

KOEO:

157-MAF Circuit Lower Than Minimum volt

Is my MAF out?

216-Coil #2 Primary Circuit Failure

Coil pack or wiring to coil pack?

KOER: (Cylinder Balance Test)

"Check Cyl. #3 Contribution or Balance Fault"
"Check Cyl. #4 Contribution or Balance Fault"

I would assume due to the code 216?

 

[projectSHO89]

Hmm. Those codes indicate BOTH a MAF and a probable DIS/coil/wiring failure.

My suggestion would be to inspect the wiring connectors at both the DIS and the coil pack and, if nothing is amiss, to replace the DIS module.

As far as the MAF code, I'd clean the sensor wires (I use brake parts cleaner spray or, if I have it, electronics parts cleaner), check the connector, reset the computer, and keep fingers crossed.

Steve

 

[hawkeye18]

+1. How your MAF *and* your DIS/coil pack went out at the same time is beyond me, but - like everything - it is possible. Perhaps the DIS went out, making the engine shake and yank out the MAF connector?

Anyway, the MAF is much easier to troubleshoot than the DIS is. Clean it out and plug it back in.. if you still get that code (after clearing them, of course), then the MAF is bad.

As far as the DIS or coil pack goes, advance auto tests them. Not all of them still have the adapter for them, so call around (it's kind of a "well we got 'em in the back somewhere" thing, they aren't tested often). Autozone might do them as well, but I don't have any experience with that.

You will need, IIRC, a 4.5mm socket to extract the DIS bolts. It might be 5mm. If you don't have them, just get a cheap 1/4" socket set and you should be fine. Take the DIS off and have them test it. If it fails any portion... well, there you go.

If it passes, have them run it again. Or even two more times. They can, and will, fail intermittently. If it passes repeatedly, then it's more than likely your coil pack.

When you reinstall your DIS, make absolute sure that you clean the back of the DIS and its mounting surface off real good with cotton balls and >=90% isopropyl alcohol, then apply a thin coat of heat sink compound (you know, like the stuff you put on CPUs - yes, Arctic Silver 5 works great) to the back of the dis and make sure you get complete coverage before installing. This will greatly help to prolong the life of your DIS, whether current or new.

And yes, there was much debate in the past about whether to use dielectric grease or heat paste, but it is definitely heat paste -- read the SHO engine book if you don't believe me. If you need to figure out where it is, PM me.

Hope this helps... oh, and obviously if the MAF code doesn't go away after cleaning it, you need a new one...

 

[projectSHO89]

Don't bother taking the DIS to a parts store for testing. It's intermittent and will, with 99.99% certainty, pass any bench test. Just replace it and be done with it.

FWIW, the factory service manual SPECIFIES dielectric grease as heat sink compound. While I don't agree with it, it is what is specified. Probably was irrelevent to the original failure anyway.

Steve

 

[hawkeye18]

The factory service manual is wrong. This has been hashed. I will paste out of the 89 SHO Engine Service Manual:



I don't know what you interpret "thermo-grease" to be, but I call it heat paste.

FWIW, I had a DIS test bad on me that was causing a misfire. I know, I know, it happened to me so it must be that way 100% of the time, right? But it does happen.

 

[AREA 91]

DIS module is retained with 5.5mm bolts. The bottom two bolts provode the ground for the module.

 

[projectSHO89]

The factory service manual is wrong.

No, the factory service manual is not wrong. The dielectric compound specified also has the needed characteristics to serve as a heat transfer compound. It is not the same as the stuff at AutoZone.

Let it go.

Steve

 

[Phoenix]

I had the same code/symptoms in my green 94 for the misfire. Change your DIS and call it a day.

The grease is not that much of a deal , most of it goes out anyway when you screw it cose 100% of both surfaces are flat.

 

[USHOMEISHOU]

:thankyou:Thanks to everyone
It turned out to be the DIS. The one that I removed had a blotch of heat paste the size of a silver dollar on the back of it (not nearly covering the back of the entire DIS module) this probably is what led to it failing.

Questions:
1. had to buy a new DIS from Vatozone (not a motorcraft part) how long do you estimate before it fails?

2. I have installed ignition modules before (not this type, but the same premise) they usually came with what I understood as dielectric grease (consistancy and color of toothpaste) this DIS, however did not. the only thing that vatozone had available was their little "ketchup packet" of dielectric grease at the counter, but this was not the type that I had used before, it looked like silicone(in terms of color and texture) It got me home but I still have a feeling that it's the wrong stuff.

 

[hawkeye18]

Go to radio shack and get their little $4 tube of heat sink compound/heat transfer paste. This is the stuff you need. As *cough* others have stated, dielectric grease will technically work, but much like wrapping electrical tape around a frayed battery wire, it isn't the right solution.

Once you get the correct compound (and yes, the exact compound Ford specifies is indeed a form of heat sink paste), you will need to clean the old stuff off well to get the maximum benefit. Isopropyl alcohol and cotton balls work wonders.

I have seen a lot more DIS failures lately, and almost every one has had one thing in common - poor distribution of heat paste, or it was dried and cracked (i.e. not functioning any more).

I would posit that (yeah, I watched "Fringe") a good maintenance practice would be to remove the DIS and clean/reapply heat sink paste to it. It will keep your DIS cool(er) and happy(er).

DISs are not cheap, as you just found out.

On a side note, when my DIS blew out on me (it had a tiny dab of paste in the middle) and I got a new one from advance auto, it didn't work... but it worked just fine on my wife's 95 ATX, and the motorcraft unit from hers worked just fine on my 94 ATX... never did figure that one out, but it's been over a year now and no problems.