93' ATX...Dropping (2) Cylinders when warm

[jebooker]

The saga continues...in my last post (stumbles/hesitates) I said there was a KOER code 217..Primary circuit failure, ignition coil #3. After the usual 5min run well until warm, then hesitate and run poorly routine, I did some more investigating. I listened closely and noted that there were two cylinders that were not "firing". To confirm this I pulled the plug from the cylinder that was easiest to determine, that being #4? (drivers side, rear bank). To my dismay, there was a raw fuel soaked plug.

SO....Since I have A. Recently replaced the Plugs/Wires/Coil, and
B. Knowing this only happens when warm, what is my next move?? Any bench test for the DIS?

 

[DVJ38]

The problem deffintly sounds like it has to do with a coil to me. I believe we have the waste spark system since we have the dis. This means that it fires those 2 cylinders at tdc (companion cylinders), one on compression, one on exhaust. So that much makes sense.

You said you replaced the coil, but the problem remains only when hot? Check the ground, make sure you have continuity through the ground wire. Also check where it contacts the metal and the coil, make sure it is clean and even connected securely.

The dis could certainly be the cause. Sometimes electrical modules have glitches that only occur every so often. Can't remember how to test it though. I'm just learning about this sort of thing now in school, so I'll see if I can get some more info.

 

[projectSHO89]

The DIS module seems to be the most common reason for this failure. Thermal failure. Inspect the connectors before condemning the module.

Good luck.

Steve

 

[jedhead]

If the cause is heat related, buy a can of compress air at radio shack. Hold the can upside down and spray the suspected part. The part will cool and start working.

Bob

 

[jebooker]

If the cause is heat related, buy a can of compress air at radio shack. Hold the can upside down and spray the suspected part. The part will cool and start working.

Bob

I have throughly cleaned the DIS, and used a jewelers file to shine the contact points on both the module and the connectors....to no avail. I assumed there would be a code thrown for this...or is this the Genesis of other component failures, and I'm to arrive at this point through process of elimination? I also assume this (DIS) is unique to the SHO, and will therefore (as per usual) be...... 1.Hard to find, and, 2.Expensive !

 

[jedhead]

Thunderbird SC uses the same module. Did you try cooling components when the engine is missing like I suggested to isolate your problem?

Bob

 

[jebooker]

Thunderbird SC uses the same module. Did you try cooling components when the engine is missing like I suggested to isolate your problem?

Bob

Not yet...will try that this AM...

 

[jebooker]

Tried the "cryo" treatment....no change, still missing 2 cylinders

 

[SHOTOGO]

Had the same problem in my car,turned out to be the DIS. There's an easy test I found to determine whether it's the coil pack or DIS. There's four wires going into the coil pack from the DIS, the ones you need to look for are the three with yellow in them. Each wire fires one of the coils in the coil pack. You can take a test light and test each wire when the car is having the problem and if one of the wires is not making the test light flash then it is the DIS, if you are getting a flash from all three wires then the coil would be the culprit. It's probably a good idea to check the three wires when it's running fine to make sure you have the right three wires.

Rick

 

[jaded93atx]

Another easy diagnostic for the DIS is to remove it and take it to a parts store and have them test it for free. green means good, red means bad.

 

[projectSHO89]

It will likely test good at the store since it takes 10 minutes of operation for the symptom to show itself.

Rick's idea is an excellent one. Try it.

Steve

 

[jebooker]

I'm on my way to NAPA...I'm going to "pre heat" it in an already warm oven, (180deg), then keep it hot in an insulated sleeve....anything's worth a shot. If it does indeed show good, I will definately try the above mentioned test procedure, when it warms a bit...it's 17deg right now! Thanks for the help...Eric

 

[jaded93atx]

The DIS warms up very quickly while they test it, if you feel you need it heated to stress test for failure then ask them to run it a second time to be sure.

 

[jebooker]

Soooooo...I put the DIS under the hood of my other car to keep it hot while I drove to NAPA, but indeed it "passed" the bench test. Now I need to remove the two flooded cylinder plugs, dry them out and start the beast. Speaking of which...what other cylinder should be out? I know #3?(drivers side, rear bank), but can't really hear the other one. The code is for the #3 coil.

 

[Rockledge]

If a coil is a causing a misfire in cylinder #3, then cylinder #4 should also be misfiring. Cylinders 3 and 4 are fired by the same coil in a V6 equipped with Ford's DIS. Cylinders 2 and 6 also share a coil, as do cylinders 1 and 5.

You should note that, technically speaking, Coil #3 (as designated by Ford) fires cylinders 2 and 6. Coil #2 fires cylinders 3 and 4, and Coil #1 fires cylinders 1 and 5.