TempBlueRidgeMark

Hi, folks. My laptop motherboard died and I can't log in to my usual account, BlueRidgeMark. I know users aren't supposed to have more than one account, but this is something of an emergency, so I'll beg forgiveness for this temporary situation. (The hard drive is almost certainly fine, I just need to get a new PC.)

I've been battling an intermittent rich condition for over a year now on my 1997 Country, 4.0. AW4. It's had a new ECU, distributor, cam pos sensor, crank sensor, and TPS about a year ago. Dealer parts, all.

Last weekend I replace the fuel pump because it was giving intermittent pressure when tested. Sometimes with the key on I'd get full pressure, sometimes nothing, sometimes something in between. The new Bosch should have taken care of that.


The intermittent bad running (very rich) condition has been augmented lately by an intermittent no start. Acts like there's no spark. Turns over just fine (please don't start telling me about battery issues!) but no fire. Then I'll leave it alone for a minute, and it will fire up normally.

It no-started on me this morning, then started, but running stupidly rich.

Yesterday I drove to work (+50 miles) and most of the way home with it running just fine, and then it started running very badly again, stupidly rich. When it happens, it's usually like flipping a switch. I/'m fine, then I'm not. Missing, not much power, black clouds when I stomp on it (which sometimes clears it for a few seconds to a few minutes.)

Pulled codes this morning when it happened. Here's what I'm getting:

P1898 Transmission does not shift correctly or Torque Converter Clutch (TCC) is not working correctly.

P1391 CMP or CKP Signal Intermittent Condition

P0340 Camshaft Position Sensor 'A' Circuit Malfunction

P0700 Transmission Control System Malfunction


Two codes pointing to the transmission (which is working just fine), and two codes pointing to the cam sensor.

Is this pointing to the NSS, perhaps?

Any suggestions?

CCKen

I have no idea what year XJ this is but the Camshaft Position Sensor determines fuel injector timing and dwell (rich/lean). On XJ's prior to 2000 it also tells the PCM what cylinder is in position to drive the ignition coil to fire the respective plug.


My first thoughts are the Cam Sensor is defective or the wiring to it is defective. A defective Cam Sensor can cause rich conditions and a no start condition.


Close examination of the Cam Sensor wiring and its connector would be in order.


If you have a pre 2000 XJ, remove the distributor cap and examine the Cam Sensor for defects.


Replace the Cam Sensor when in doubt.

TempBlueRidgeMark

Thanks for the info, Ken. It's a 97 (mentioned above).

Last summer the distributor wiped out the cam sensor as its bushings were shot. Both were replaced, so I'm leaning towards the wiring. (But I will inspect the sensor!)

Do you know where the wires go from where they exit the distributor? I traced them into the loom, and I'm guessing they go straight to the ECU. Would you know what pins? I think some continuity and resistance testing may be in order. Along with some wiggling, of course.

XJRed96

I've found bad wires in a fully secured loom within two inches of the ecm. Similiar no start issue, did u use a Mopar sensor or an aftermarket sensor?

TempBlueRidgeMark

All Mopar. The work was done by the dealer, actually. I do that when my car leaves me stranded by the side of the highway when I'm trying to get to work.

Thanks, I will be undoing a loom here as soon as I can get to it. Been working til late night and sometimes all night lately with a big project. Good thing the finale is today and I can work from home, or I'd be renting a car!

CCKen

Diagrams for the '97 Cam Sensor and PCM connector C1:



.

TempBlueRidgeMark

Thanks very much, Ken. The wiring seems to be fine, so far. I put my analog meter on it, with probes into the connectors on each end. I did a lot of rough handling of the wire loom, shaking, pulling, and tugging, and the meter never wavered. Perfect continuity for both the sensor and sensor ground wire. I ran out of daylight so I'll check the third wire (5v supply) in the morning.

Next step after that is to pull the distributor top off and see about the sensor itself.

Question: Is the PCM ground the one near it on the inner fender?

CCKen

No, it's on the engine block. See pic.

TempBlueRidgeMark

Ah, that guy.

Well, good continuity on the 5v supply pins. I treated the loom pretty roughly, so I think I'm safe in ruling out the wiring from the cam sensor to the PCM. I'll do that ground now.

Is there a way to test the cam sensor? It looks fine. Nothing as obvious as the distributor contacting it, anyway.

Peeling the onion!

BlueRidgeMark

Well, that's progress of a sort. It is no longer intermittent, and I have verified that it is a no spark problem.

Called the dealer about the cam sensor, and they said it was under warranty, so they have it for now....

BlueRidgeMark

Yep, it was the cam sensor. It came with the new distributor and the dealer installed an aftermarket part! I guess the OEM stuff is getting harder to find.

The warranty covers all but $50, so I'm getting off pretty easy.

Thanks for all the help!

CCKen

Thanks for the follow up.

BlueRidgeMark

You're welcome, and thank you again.

I consider that just basic courtesy to people who have taken the time to help. It's Forum Etiquette 101 in my book.


It's good to know those things can be intermittent. Some electrical components are all or nothing.

BlueRidgeMark

Well, it was NOT the cam sensor. Not only, anyway.

Drove it away from the dealer, a few minutes down the road it's missing again, running stupidly rich.

Bother.