Hi. I have a 92 2.3liter 5 speed Ranger that has been throwing some CELs. I pulled the codes using the flashing light method and got 223 and 224.

Sympton wise, at lower RPM she's sounds like she has a miss and kinda stutters under accleration. Then the stutter ends and it feels like it is turbo charged (!!!)until the next shift when the RPMS drop. It also smells rich ala unburned fuel from the miss.

I started checking for a spark using an induction timing light and sure enough, some of the wires did not indicate a spark. Then I dropped the light and the was the end of trouble shooting with that.

So I pulled the ICM and went to two different FLAPS. It tested bad 1 outta 3 tries at the first store. And then it tested bad 1 outta 4 at the other store.

A) How reliable are the auto store testers?
2) Since the problem is intermenent and worse when cold, the repeated tests did get the ICM warm and maybe that is why it passed on the rechecks?

Last year I had some other electrical issues as the result of a mouse moving into my air filter box. Ended up replacing the MAF as well as the coil packs and threw in some new wires and plugs while at it.

Hate to hang a $140 part if I am not atleast semi sure.

What do y'all think? Thanks

Eric

 

Well lets think about this some more. You may have more than one problem.

The trouble codes say that the computer agrees with your timing light test, that one of the coil packs has a problem & it's in the primary side. SO, at KOEO, check for B+ at the suspect coil packs electrical connector. If ok, check the suspect coil packs primary winding for continuity. If thats ok, check the wire to the ICM electrical connector for continuity, maybe that mouse has been lunching on under hood insulation, it happens!!!!

If all that checks out ok, maybe consider re-doing the ICM bench test with a spray can of "Freeze", to cool that puppy down, especially if the previous positive tests were obtained when the ICM was room temp/cold. Most electronic stores like RadioShack has the cooling spray to cool & trouble shoot electronic parts.

Edit: If you come to the conclusion that the ICM is faulty, maybe consider a salvage yard replacement, bet the price would be right.

Some thoughts for consideration, let us know what you find.

 

My paln was to come home from work and test the coil packs and then if those were okay, to try a Pull-a-Part for a cheaper 'new' ICM. Here is what happened:

I checked the B+ to the left and right connector on the coil pack and got 0.6 ohms. Within spec. Check

Nexted I tried to test secondary resistance between the connector and the spark plug wire post. I got infinity for resistance. Just to make sure, I tried each of the 4 spark plug posts with each prong. Again, no reading.

Oh, it gets more confusing...

Same with the coil pack that fires the passenger side plugs. B+ to connectors was within spec at .6 ohm, but again, infinite when testing to the wire post.

Off to FLAPS. The packs were under warrenty so they swapped them out. Just in case, i brought my multimeter to show I wasn't going nuts. Though I wondered how I was driving with two faulty coil packs. For giggles they tested the packs and got the same infinite readings. Stupid me said "Lemme test the new ones." Same deal with the new outta the box packs. Infinite to the posts.

But I said WHY NOT put new on. So I got the new ones, came home, in stalled them and on. Re hooked the ICM.

Now I have no spark. None. Zip. Nadda. Yes, all the connections were good and seemed solid. The ICM tested fine today at the FLAPS.

HELP!

 

The coilpacks secondary reading is made between the companion spark plug wire connections. They typically run around 12-15K ohms.

If you don't have any spark at all, revisit all the electrical connectors removed & maybe re-do the KOEO B+ tests at the coilpacks electrical connectors, paying attention to their connectors pins & sockets condition for corrosion, spread sockets, bent or broken pins, broken wires.

 

My plan is to start at the beginning and go connection to connection checking continuity and such. I don't like chasing wires so much. *SIGH* I will report back. Time for bed now.

 

Short update: Not good.

Longer update: Okay, so I still have no spark. Here is what I have done:
I rechecked the coil packs both primary and seconday resistances (thanks for the tip on how to do it properly). They checked out fine.

Then with key on, engine off I checked the B+ connection on the wiring harness going into the coil packs. I got a solid 12-13 volts for both.

I then checked for continuity along the wiring harness between the ICM and coil packs. I followed the color codes on each side of the harness and the I had good continuity for all of the pins going to coil packs to the pins at the ICM side.

I even swapped in a new ICM.

I have stared hard looking for loose wires and such. I don't see anything. I checked the ground strap that runs from the cab to the back of the intake manifold and that seems good.

I even cleaned the mating surface where the ICM mounts to the manifold just in case.

After all that, still no spark.

Ideas? Could the crank position sensor or such gone bad and thus not tell the computer when to fire? I am at a loss. HELP.

Thanks

Eric

 

OK, good trouble shooting feedback. Check for trouble codes again to see if any new ones are stored & post All code numbers found, as they can offer up good trouble shooting clues.

In the mean time, seeing as how both coil packs, B+, & wiring seem to check out, it would seem to suggest that coil pack ground switching to make spark isn't happening for some reason, so the trigger to have the ICM do that, the ICM itself, or wiring between the ICM & coilpacks is suspect. Seeing as how both coilpacks are now affected, look to something common to both coilpacks & the distributor hall effect trigger & it's wiring probably belong on your suspect list.

Keep us posted on your findings.

 

Thanks for the tips. I see what you mean about the problem is most likely 'upstream' since both coils packs are affected.

I stared and stared and found a broken wire. But I don't know what it is to. I'll try to describe it.

It is between the master brake cylinder and the instake manifold and comes off the main wiring harness that is headed to the ICM. It splits right near where the connector to the crank position sensor attaches to the main harness.

The wire comes off the harness and is wrapped in the heat tape so there is no color code on it. I peeled off some of the tape and I found a bare copper wire and a size 12ga all black wire. Then the wire goes to a typical one wire auto wiring plug/connector. Out the other side of the connector, the wire was broken. All that was left was about 2 inches of broken wire that I have no idea where it goes. The wire stub seemed to have a white-ish heat resistant woven insulation. Coulnldt makeout a color code on it.

The bare wire, for sure is a ground because I got continuity to the main ground.

I've stared at the wiring diagram and have not found this wire.

For giggles, I also probed the crank sensor and found I have 5 volts (which is the spec) going to the CPS. I also have a reasonable resistance on the probe side for a transducer.

So I think/hope that maybe this missing wire might be the problem. Anyone know the wire I'm talking about?

Thanks.

Eric

 

Final Update (hopefully)
The truck is running and running well. The neighbors probably thought I was nuts doing laps around the block to test it.
I had my new ICM tested and one autoparts store it was bad, the place where I bought it said it tested fine but took me at my word and swapped it out.

Came home, installed it, tried the key and no dice. I called the dealer, told my sob story to the service manager, set up an appointment, was about to call a towing service when I thought, "Oh, what the heck." I went through as many connectors and connections as I could find, jiggles this and that, turned the key and she fired up.

Intermintent electrical problems really are hard to check. But I do think the old PCM was bad because I am no longer throwing codes. And the RPM miss is gone. This repair wasn't a lot of physical work but it did rack my brain many an evening. I like bad bearing better. Much more cut and dry than electrical. Thanks PawPaw for your help.

Eric

 

I know what you mean about intermittent electrical problems, as I just fixed a long trouble shoot on intermittent stalling on my 94 Taurus 3.8L.

Now that it's running & you know the problem was no spark, with it running, one at a time, wiggle & thump all those upstream electrical connections & items that are responsible for spark to both coilpacks & see if you can induce another stall. If you can, you can likely pinpoint & repair it, because it'll likely happen again if you haven't located & fixed the problem.