ckp failure?

[FritzTKatt]

As a part of my ongoing problems... my old ckp produced about 2.2vac. I read they need to make between 4 and 7vac. Replaced and now I get about .2vac. The two sensors have the same resistance between pins. I seriously think the ckp is the root of my problems. What should I do? Can I tell if the harmonic balancer's indexing key has broken without pulling it apart?

 

[FritzTKatt]

Another question. Who has rebuilt, or split open a GOOD harness? How does the ckp shield (pin 7 at ICM) connect?

EDIT: another question. Should the coil outputs, where the plug wires connect to the coil pack, have 12v koeo? I have 12v at the pig tail, but wondering if the connector itself may not be contacting the pin on the coil pack. This would obviously appear to be 100%, but with no contact, I'd of course get no voltage to make a spark, regardless of the icm grounding the circuits out as the ckp determines which one to ground out...

 

[FritzTKatt]

I verified my compression at about 140psi on all cylinders. Is it blow by from constant cranking that I have a smell of fuel in the oil? I'm going to loose it if another motor is toast without even running... I referenced the "efi bible" in the tech section, and have narrowed it further. Pip signal to pcm, (probe wire at icm and ground on battery) has a pulsing signal as listed in the book. The "vrs bias" checked at 1.5vdc even, 1-2vdc is the spec. My ckp signal is weak at the sensor and at the icm. Two different sensors give about the same results. The book lists > 1vac as minimum. I get .3-.5vac. I have 0 resistance between the ckp pigtail and the icm pigtail.

The sensor mount has some wiggle room, and I tried to tighten it down in different spots to see if the signal would change. Nothing. The pulley/teeth are clean. I'm not sure what can be making this not give me a good enough signal...

 

[FritzTKatt]

Noone has ANY ideas? I don't want to be that guy, but c'mon, I know ya'll have something to say after those views. I'm at such a loss for ideas here...

 

[RonD]

'94 4.0l will use an EDIS-6 module for spark
Usually located on the Rad support, my '94 has it on the grill side of rad support, and drivers side of rad support.
I have seen these damaged from front end collisions and then give intermittent issues because they were not replaced.

EDIS module connects directly to the CKP sensor and directly to the coil, it runs the spark, with or without computer(EEC, PCM) input, this input is for better spark advance but is not required for engine to operate.

Coil pack gets 12v when key is on, other 3 wires are grounds controlled by EDIS module.
There are 3 separate coils inside the coil pack, they share the 12v only.
A coil is a transformer so there would not be 12v at the spark plug wire connections when key is on, there is no power connection between Primary coil(12v) and secondary coil(spark plug wire), they do share a ground so can be tested with OHM meter.
Google: How to Check an Ignition Coil Pack the easy way
it is a youtube video

This is a good page for EDIS module info: http://www.dainst.com/info/edis/edis.html
You could ohm the wires to check for shorts or breaks

I have never come across an intermittent CKP sensor, dead yes, but not intermittent.


Do you have no spark at all or do you get some spark?
On rare occasions I have read that the woodruff key failed on main pulley so CKP signal didn't match actual TDC, but you would still get a good spark just not at the right time

 

[FritzTKatt]

AFAIK I get no spark. Maybe I missed something

Can I check that key without pulling the pulley? I have wiggled the pulley and it was solid. You know by now that my ICM/edis module is good. My ckp is the problem, but thinking about that key, that could explain it. Since the ckp itself (unplugged from wiring, and cranking engine, not expecting a start) is producing a weak signal. It produces the same signal plugged in, testing at the icm pins. So my wiring isn't losing any of it.

All the help is appreciated, Ron.

 

[RonD]

If woodruff key failed you would still get strong spark just not at the right time, assuming, of course, the pulley(sensor's ring gear) was still turning with the crank.

EDIS modules rarely fail unless physically damaged.

If CKP sensor is generating any signal at all it is most likely OK, yes spec is .5-1.0vAC but EDIS is just looking for the wide "tooth" on the ring gear.
If you have pulled out or can access the EDIS module then test CKP there and also test that EDIS has 12v with key on, pin diagram in above link, and that the Ground is still a Ground, EDIS Ground runs the coil spark, so if EDIS ground is not good there would be no spark.
The EDIS 12v along with the coil packs 12v and fuel injectors 12v comes from the EEC relay via spliced wires, splices can fail.

OHM out the coil as well but generally only one coil in the pack will fail so you would get a missing engine not a no start.

 

[FritzTKatt]

I can rechecked, but edis gets the 12v koeo, ground has like 1ohm between pin and battery negative. Coil gets 12v koeo. I have fuel shooting into the cylinders (maybe not at the right time, but there's fuel nonetheless). I have continuity between coil pins and icm pins. I have checked the coil against the book, a new in box, and a random. All 3 coils tested the same against the book values.

EDIS module is new, PCM is new. See how confusing this is getting?

 

[Snoranger]

I went back and read about your first go-round with this problem. You changed the connector and/or harness to the crank pos sensor, right?

Recheck your work carefully, there is a positive and a negative side to the sensor. If these are wired backwards, the injectors will fire but you won't get spark. I found that out when I built the harness for my EEC-IV SOHC. I also found out, sometime between '95 and '01 Ford swapped the positive and negative pins on the sensor but used the same connector.

 

[FritzTKatt]

Afaik the sensor puts out AC, so polarity is negligible. The manuals say test with the mm on vac. I put it the way it was originally. I could try to swap it around.

 

[Snoranger]

Afaik the sensor puts out AC, so polarity is negligible. The manuals say test with the mm on vac. I put it the way it was originally. I could try to swap it around.

Yes it puts out an AC signal... But trust me, it's polarity sensitive. I found out the hard way.

 

[FritzTKatt]

Well there's no way to check afaik... I put enough extra wire in there so i can pull it up into the engine bay and cut it like 6" up at the new splice and swap the wires around. The pigtail on the new connector is blk/blk so you can't distinguish the wires.

Also, where does the ICM ground out exactly? I found the closest ground to it, on the rad support next to where it mounts, but it goes through a branch or 2 on the harness first so I'm not 100%. It gives me no resistance to that spot, so I'll take it.

And more importantly, where does the ckp shield wire go to ground out at? I've hit up all the ground points I can find, but would like to make sure.

EDIT: still man, appreciating the help. Gratz on the ASE certs btw, just noticed.

 

[Snoranger]

Can you pull the connector down under the truck? If you can, get a small pick, disassemble the connector, and swap the pins. IIRC, that's what I did.

IDK where it grounds on your truck. I don't have an EVTM for a 94 Ranger. As long as you have a good ground at pin #9 on the ICM, I wouldn't worry about where it comes from.

The shielding ground should be pin #7 off the ICM. Even with that disconnected, the truck will run. It's just for radio frequency interference.

As for the ASEs... Thanks. My new job pays me $175 a year for each ASE (max 15). I took all 15 in about a month and became master certified in both auto and HD truck. They basically said theyll pay me an extra $2600 a year AND pay for the tests... I'd be stupid to say no.

 

[RonD]

Yes, just test the Ground at the EDIS module connector, connect OHM meter to that pin then to engine ground.

 

[FritzTKatt]

Could you provide more details on the connector disassembly? I probably won't be able to get on it for a few days. That's legit on the ASE tests. Not all that much a year, but who's going to complain, especially for how good that should look.

Ron, that's what I did and it was good. Thanks for the confirmation.

EDIT: youtube gave me a pretty good idea of what to do. Seems pretty easy if it doesn't fight you. Feel free to elaborate if you would like, though.