Bizarre issue at wot throttle P1391 and P0705

This just started the other day while trying to pass on some rather steep hills, i,ve noticed it driving a little more sluggish lately but didnt think much of it until it through the codes and started shifting weird. It isnt shifting from third until about 3k, but at 1/2 throttle and below it's running fine. The crank and cam sensors are both oem and less than a year old, distributor is new, and I had just cleaned the nss about a year ago. I went ahead and pulled and rebuilt the nss again, swapped the old cam sensor in, and pulled the crank sensor out and cleaned it. I also found out my cat was busted while I was down there so thats not helping things. I'm thinking my TPS might be causing the shift point issue, but I really don't know. Any real guidance from the jeep whispers would be helpful at this point, this old xj is killing me.

Fix any known problems.

Follow the trouble codes. New sensors do not automatically mean good sensors, test them. Visually inspect and test their wire plugs and wire harnesses for corrosion and damage



P1391 - Intermittent Loss of CMP or CKP Signal. Loss of the Cam Position Sensor or Crank Position sensor signal has occurred.
P1391 – Possible symptoms:
(1) random misfire/stumble/stalling, often over bumps or right turns and when going into reverse.
(2) shorted out the Fuel pump/ECU power wire.

Possible causes
- Faulty Camshaft Position (CMP) Sensor
- Camshaft Position (CMP) Sensor harness is open or shorted
- Camshaft Position (CMP) Sensor circuit poor electrical connection.

Symptom:
P1391-INTERMITTENT LOSS OF CMP OR CKP

CMP SENSOR OUT OF SYNC
-DAMAGED TONE WHEEL/FLEX PLATE (CRANKSHAFT)
-DAMAGED TONE WHEEL/PULSE RING (CAMSHAFT)
-IRREGULAR LAB SCOPE PATTERN OF CMP SIGNAL

INTERMITTENT CKP SIGNAL LOSS WHEN WIRING IS WIGGLED
-IRREGULAR LAB SCOPE PATTERN OF CKP SIGNAL
-WIRING HARNESS INTERMITTENT

INTERMITTENT CMP SIGNAL LOSS WHEN WIRING IS WIGGLED
-SENSOR CONNECTOR/WIRING
-CAMSHAFT POSITION SENSOR
-CKP SENSOR CONNECTOR/WIRING
-CRANKSHAFT POSITION SENSOR

Potential Fixes:
Fix #1:
Inspect your wire harnesses for damaged wires, chafed insulation, or failed wire splices. Use a volts/ohms multi-meter to check the resistance of the ground wire circuits from each sensor. Replace corroded ground wires/connectors and clean ground wire connection points.
Fix #2:
Timing may off. Re-index the distributor/cam sensor per the FSM instructions, or replace faulty distributor/cam sensor pickup module.

Google Scan Tools, O-Scopes and Toothpicks, and read the article.

A mis-indexed distributor/cam sensor may exhibit surging, light bucking or intermittent engine misfiring. This will most likely occur when the vehicle is at operating temperature and under a light load at approximately 2,000 rpm. The proper indexing procedure must be used as outlined in the service manual.

I've checked the timing, its good. If you're honestly telling me I can't get a year out of a oem crank sensor than I might as well burn the delicate little flower to the ground, cut my losses and buy a geo metro. This thing has been constantly broke in one way or another for over a year now and I'm about to run out of patience with it.

Please elaborate "at wot throttle"

Only at WOT? Why are you running at WOT?I would fix the Cat problem and start over. I had all sorts of mis fire codes that turned out to be a bad Cat 2 years ago on a Ford, and on other rigs they, including my 87 XJ, they caused low power even at WOT. Maybe heat from the CAT and back up of exhaust is throwing the wrong codes?

Raine883 said:

I've checked the timing, its good. If you're honestly telling me I can't get a year out of a oem crank sensor than I might as well burn the delicate little flower to the ground, cut my losses and buy a geo metro. This thing has been constantly broke in one way or another for over a year now and I'm about to run out of patience with it.

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I agree with one exception, an overheating busted cat backing up exhaust can pour heat back up to the flex plate/CPS sensor. There is a simple ohm test for the mounted, unpowered CPS.

Ecomike said:

Please elaborate "at wot throttle"

Only at WOT? Why are you running at WOT?I would fix the Cat problem and start over. I had all sorts of mis fire codes that turned out to be a bad Cat 2 years ago on a Ford, and on other rigs they, including my 87 XJ, they caused low power even at WOT. Maybe heat from the CAT and back up of exhaust is throwing the wrong codes?

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I was in the process of passing someone who doesn't understand that driving 45 in a 75 is unacceptable. I changed the TPS and my trans is acting right again. I wailed on my cat with a ball peen hammer and was able to free it up enough to run. I've got a new cat ordered and it should be here by Friday so hopefully this'll solve most of my problems.

Sounds good, now just make sure the engine is not running rich (check the pre cat O2 sensor data) and once the new cat is installed check the exhaust for gasoline odor, and the cat at night to see if it is glowing in the dark, as that is what usually damages a Cat converter, running rich.
Oh, and I have been known to do 35-40 on the freeway, even 0-5 mph on the freeway, as I live in Houston LMAO.:laugh3:

Tim_MN said:

Fix any known problems.

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At Wide Open Throttle, the transmission will only shift at or near maximum RPM (close to red line). If the engine is struggling to get up there it may not shift until you let up on the throttle.

Tim_MN and Ecomike had some good suggestions to begin your trouble shooting.

techno1154 said:

At Wide Open Throttle, the transmission will only shift at or near maximum RPM (close to red line). If the engine is struggling to get up there it may not shift until you let up on the throttle.

Tim_MN and Ecomike had some good suggestions to begin your trouble shooting.

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I think I have seen that behavior with my Renix jeeps at times, but at 1/2 to 3/4 of WOT (apx). And not sure that is all the time, as I have a light foot and a heavy wallet LOL:laugh3:

Ecomike said:

Sounds good, now just make sure the engine is not running rich (check the pre cat O2 sensor data) and once the new cat is installed check the exhaust for gasoline odor, and the cat at night to see if it is glowing in the dark, as that is what usually damages a Cat converter, running rich.
Oh, and I have been known to do 35-40 on the freeway, even 0-5 mph on the freeway, as I live in Houston LMAO.:laugh3:

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I have no doubt the cat is trashed its sounds like a maraca in my exhaust and the flaming packing coming out the tailpipe is a sure sign. I've also noticed its running about 5 degrees warmer than usual. Hopefully this will give me a little breathing room, I love turning wrenches, but I'm about ready to not work on it every day I have off.

In that case the muffler passage ways may be clogging also.

Ecomike said:

In that case the muffler passage ways may be clogging also.

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I'm running a chambered muffler so when I replace the cat I figure I should be able to shake most of the trash out of it.