Hello! I recently changed the plus and wires on my 94 Explorer. It has the 4.0L (pushrod engine) w/ 128k miles. I used platinum plugs and Bosch 8mm wires. Now the darn thing runs worse than ever.

The plugs are gapped at .054 and I have confirmed the wire routing with the manual and had the neighbor veiw the routing as well. Icheched the resistance of the plug wires and found them to be in range. Well, in all of my wisdom I dug out the timing light and have inductive pick-up out of 4 of the 6 cylinders. The #5 and 4 cylinders are the non sparkers.

I have since performed a primary resistance check of the coil with no problems noted. During the secondary check I found all the banks to have a higher than normal resistance. With that in mind I guess I am confused as to how only 2 cylinders on two seperate banks have gone bad.

So here is the root question. Is there something I'm missing or do I need to replace the Coil?

Thanks in advance!

 

Tried a new coil to no avail. I am completely confused now! Any suggestions would be appreciated.

 

Could it be the plugs? When I first bought my '92, I changed the spark plugs and decided to try platinum plugs. My engine performance went bad. I heard a mechanic suggest that one should stick with copper plugs on older engines, so I took back the platinum plugs and put copper plugs back in. My engine performance returned to normal. As I understand it, platinum plugs have a lower resistance, therefore they will fire sooner than copper plugs, all else being equal (gap, etc.), thus throwing off the engine timing. This may not apply to your '94, though. I'm not sure.

Hope you find the problem.

 

Did the problem begin when you replaced the spark plugs , did you use Bosch plugs ? If so Im willing to bet thats the problem . That engine will run much better with the Motorcraft Spark Plugs AWSF - 42PP . Id even open the gap on those to 0.056 .

 

Thanks for the response. I also thought it could be the plugs. I placed the originals in with the same result. So I really don't believe it is plug related. I also place the old (what I could salvage) wire on to no avail as well.

In addition I have removed the SPOUT plug to take out the computer timing with no result as well. I also reset the computer and checked for codes. No help either.

As I mentioned before I even tried another coil which had the same dead swires as well.

How does the ICM direct the coil and with that in mind does the PCM have any play in this?

I tell you I'M AT WITS END!

Thanks for your responses!!!!

 

[updated:LAST EDITED ON 25-Feb-02 AT 12:26 PM (EST)]Chip, let me try and help out some.

I've reviewed my Haynes manual and this is what I deduce. The coil pack gets its input from the Ignition Control Module (ICM). The ICM has a 12 pin connector. 1 thru 4 are from the Electronic Engine Control (EEC) module, later named the Powertrain Control Module (PCM).
So both these units play a role in spark.

As an old rule, if something is wrong check the last thing that you did, which you have done. At the risk of insulting you, please check the wires one more time. See below:

3 - 4
2 - 6
1 - 5
COIL

3 - 6
2 - 5
1 - 4
ENGINE

This is easy to mis-route. If ok, continue;

Since your old coil checks out fine, I recommend that you check the input connector to the coil. This will determine if the problem is further upstream (ICM or EEC). To perform this test you need an LED test light. A regular resistive lamp test light will not do.

Connect the LED to your battery positive (+), and the other side to negative terminal connection at the coil. Pull your connector, and looking back into it with the clip/latch on top, the left 3 terminals are coil input negatives. One terminal for each pair (1-5, 2-6, 3-4). Connect the LED to the far left, crank engine and LED should flash. Do same for next 2 terminals. The 4 (right) terminal is 12V when key is on.

If LED does not flash, it could be the ICM. Haynes does have a test for the ICM but you also might want to check the harness between the ICM and coil to rule out the connector. On the ICM terminal 10 goes to coil 1, 11 to coil 3, and 12 to coil 2.

Ask for more help if you need it.

 

I agree that it sounds like the input to the coil bank is missing. The LED test light should pinpoint the problem. Make sure these connections are clean and tight.

Winford

 

Hello All!

Thank-you for all the input. I have the dumb thing running again. I removed the coil pack, ICM, re-gapped the plugs, ohmed out the wires and reset the computer. I gave the ICM and the coil a shot of super freeze before replacing every thing. Don't know what it was but it runs fine now. Must be gremlins! Again thanks for the Help!!!!