1992 Ranger 4.0L Misfiring
 

Hi!

New here and got a problem with my Ranger. Tried to search the forums but can't figure out where to start / what to do.

Specs: 1992 Ranger XLT 4.0 EFI OHV A4LD 2WD 200K++miles!

Exact description:
When starting cold, the engine runs fine, after 10sec-1min the engine starts to misfire and then the misfiring gets even worse... Sometimes it recovers and goes back to normal and the fault won't show up for 50miles or so. But it comes back and lately it's been more frequently.

It's not using any oil or coolant, the intake gasket is swapped some 1000miles ago, (coolant leak). It feels like at least 3 cyls are missing. There's no power really...
When this accures, the tacho is "jumping/dropping" rapidly. I'm pretty shure it's ignition related. The CEL comes on as well, recon it's because of major misfire...

Start with? Coilpacks? There must be som kind of cranktrigger/camtrigger/ hall sender or something? Must be some connection between the misfire and the tacho behavior? The enging is NOT dropping 2000rpms in a fracion of a second, I'm quite shure about that...

The knowhow of these US spec. trucks in Sweden, is pretty low... No point of taking it to the Ford service station.

My spelling may not be all that good, hope You can understand anyway...

Thanks!

/ Johan, Sweden (yep, that little country with a lot of blondes and so on... No, 90% of the girls are NOT called "Inga", believe it or not)

Welcome to FTE. This is a great place for help. I'm sure others will chime in and offer suggestions and advice. Have you been able to read the trouble codes. That's the place to start and will give the rest of us a better idea of the problem(s) and possible solutions. There is information in the Ranger Technical Information section at the beginning of this list. Look under "EMISSIONS," especially, "Pulling EEC IV Codes" and "2 and 3 digit EEC-IV codes". That will give you some ideas about how to access the codes and find out what they mean. If you, or someone you know has an OBD-1 code reader, use it to get the codes. Perhaps your low tech Ford guy can do it for you. Once you have the codes, then you will be able to replace the part or parts that really need replacing. Good luck. When you get the codes, post them here and we will help you to get you truck running the way it should. By the way, when was the last time the engine had new spark plugs and wires?

The ECU stores the codes. Some are accessed with the ignition key on and the engine off (KOEO) and others with the key on and the engine running (KOER). Does your reader have a manual? It should tell the procedure. Good luck.

Seeing as how you had a intake side coolant leak & it takes a while for the problem to show up, say about as long as it would take an O2 sensor to warm up enough to begin to come online, be sure to check your O2 (Oxygen Sensors) output & switching speed, as they don't like coolant. The cooant leak could have damaged one or more of the sensors, it doesn't take much.

So if the coolant leak favored one bank of cylinders, pay close attention to the O2 sensor in the exhaust manafold/down pipe for that bank. Look for slow or no O2 response, low output, or slow switching speed after it warms up.

Do post ALL the computer trouble codes found.

Let us know what you find.

Disturbing...
 

Well, it turned out to be the coilpack. The coil closest to the radiator (cyl 1&5) was dead. Replaced, the car runs fine.. For about 10miles, then the same thing again. The same coil in the coilpack dies. No spark what so ever...
WHAT?! Measured the cables, 1,2,3 had 7,3-7,4 kilo-ohms. 4,5,6 had 14,4-14,6 kilo-ohms of resistance. Seemes ok, as 4,5,6 are much longer. What the heck is happening?!

Why is the coil burning up? My know-how tells me cables, but I could need a little help here...

Thnx.

/Johan

I'm not sure its the coilpack. Rather I suspect that the coilpack is not getting the spark trigger, which incidentaly will also cause a loss of tach signal. The Cam position sensor is responsible for this, so I would suspect that maybe the cam sensor is not working properly.

I hope that too, but something tells me it's not the case.. I measured the resistance of the old coilpack. When measuring between the secondary coils I got these readings; (I measured between the plug wire fittings)

Cyl 1&5 Endless, O.L
Cyl 2&6 14,85kOhms
Cyl 3&5 14,85kOhms

The coil in front(closest to radiator), for cylinder 1 and 5 is cracked open from heat. Smells like EMS (EMS is what I call ElectoMotorSmoke ;-) )

_____

The front coil of the new coilpack got PRETTY hot, and when I measured as described above on this new coilpack I got the same reading. That's why I guess that the front coil is burnt, AGAIN )=

Is there anything else but plug wires that can burn a coil that quick?

(Yep, I am going to change the wires, however I still need to replace the coilpack, again, and I don't wanna burn a third one...)

Thanks a million!

/Johan


Edit: Is the ignitionsystem a CDI och TSI type?

sounds similar to a problem i had with my '93 4.0. intermittent misfire, jumpy tach, and down on power. it was the ECM. the problem is i'm on my fifth one and nobody can tell me why they keep going bad. once it does they say they can't get past it in their diagnossis and when i replace it there ain't no code. so now it's part of my bienial maintenance schedule. good luck.

Does your ECM eat coilpacks? Mine does as it seemes.

nope. thought it did once and replaced it turns out it was never bad. now i got a spare

I'm not all that sure about this, but aren't the 3 coils in the coilpack identical? and if measured they should get the same value?

Any kind one out there know the wiring schematics of this ignition system?

Thanks for all your effort!

/Johan

EDIS module?
 

Found This! description of the Ford EDIS -6 ignition system. I quess that's the one I have in my truck?

Is it possible for the EDIS module to cause these troubles and burn coilpacks?

If so, where in the vehicle is that evil thing mounted ? The hunt is on...

Is the EDIS module also called "ICM"? Ignition Control module? I found This and much is pretty much the same, however I haven't burned any fuses ..yet.

Am I getting close?

Regards!



/Johan

Hey TheSwede,
The same page that you linked us to says this

"If you go to a salvage yard for EDIS modules, they are usually located in the engine compartment on the driver's side inner fender. The modules have a EDIS-4 (or EDIS-6 or EDIS-8, depending on number of cylinders) sticker on them. Try to take the connector as well, as well as the ignition coil pack(s) and connectors"

My '94 does not havethis sticker on the ICM. Therefore i would believe the the '93-'97 do not use the EDIS system.

Solved!
 

The neg. cable to coil 1+5 had been rubbing itself against the battery plate. Just beside the EDIS-6 module. The module was mounted behind the right headlight. Exchanged a piece of cable, a new coilpack and the truck runs like never before. Sweeet. Just took a while following that suspected piece of cable backwards from the coilpack.

/Johan