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-   -   1998 P1391 trouble code...stumped (http://www.wranglerforum.com/f282/1998-p1391-trouble-code-stumped-231478.html)

motoxrider365 03-30-2013 04:29 PM

1998 P1391 trouble code...stumped
 
Hey folks, I'm new here. I got my 1998 Wrangler (2.5L), manual trans, about a month ago. I've been reading threads on this site amongst other sites like crazy trying to get rid of a P1391 code (the intermittent cam/crank position sensor code). The car has about 150k miles on it, rebuilt by the PO.

So, my question is, what in the heck do I do to get rid of this stupid code. I have to get it cleared for emissions, and it's been the most stubborn code ever.

The car ran when I got it, even with this code. It had some running issues no doubt, so I changed the wires, cap, plugs, and rotor. The car ran a heck of a ton better after that, but still had the very very slight rough idle. So this is when I scanned for codes, and found the P1391. Starting my research I came across a ton of instructions, so here is what I've done. Clearing codes at each change.

*Replaced the cam sensor (under dizzy cap) - Did nothing different.
*Replaced the crank sensor (bell housing) - Seems to have improved my idle. Still throws code
*Checked resistance to ECU for both sensors. - zero resistance to the ECU. Still codes.
*Checked for signal at ECU. - Cam sensor shows 5 volts and 0 volts as it should, and I get good pulses from the crank sensor.
*Used Dielectric Grease at ECU connection and both sensors. - No affect, still codes.
*Checked the distributor shaft for play. - It's solid.
*Checked flywheel for missing teeth. - All teeth are there.

So at this point im like what the feck. I want to think it's the computer. I'm thinking the PO was having this problem because he rigged up the dash lights. Taking the check engine light and disconnecting it from the check engine light socket, and directly wiring it to mirror the illumination of the check gauges light. So stupid me bought the car with this problem.

Anyway, what I have yet to try is soldering the connections for both sensors, but I would rather not do that, just for the sake of replacing down the road. The fact that the new cam sensor did nothing different, and the new crank sensor did, and the fact im getting a good signal at the ECU makes me think the problem is not the male-female connectors. But if you all think that the current sensors I have are good, I will try the solder. I'm looking for a second opinion.

Well, that's all the info I have. Nothing fixed the problem so far (except maybe the crank sensor. The car really does run nicely now.). I HAVE reset the adaptive memory (as per instructions on this side, the whole 30 seconds touching thing, headlights on off). It ran rougher after that, so I'm inclined to believe I did that right. Obviously still no dice.

When the code is thrown it shows up as a pending code within 10 seconds of starting the car after clearing codes. Then after shutting the car off, and restarting the car, the code sticks, and is stored. This pattern has not changed no matter what I have done to the car. More to lead me to believe the computer is being a turd. I've seen reports that it can happen in a few miles or here or there...this is pretty much the same every time.

I'm all ears folks! I really could use the help on this one, I need the car to pass emissions by the end of April or I can't renew registration! I hope I provided enough info. Thanks for the help everyone!

sporty95f150 03-30-2013 05:04 PM

I have this problem on and off, I have been through several Sensors. Ultimately I purchased an OEM unit from the dealer and it fixed the problem. Most of the aftermarket sensors just dont have the quality and send improper data to the ECU.

motoxrider365 03-30-2013 05:49 PM

What do you mean by on and off for your situation? For the OEM sensors, did you replace both?

sporty95f150 04-04-2013 01:36 PM

it would constantly throw the code, every once in a while it would start to stumble really bad, I would replace the unit under a warrant and a few months later it would repeat. When I purchased an OEM crankshaft position sensor the problem stopped.

motoxrider365 04-04-2013 01:40 PM

I sure hope I share your problem! I ordered both sensors, I'm certainly banking on this solution *crossing fingers*

I'll update when the sensors come in the mail. Thanks for the help!

InvisiblePants 04-04-2013 04:36 PM

Are you using oem mopar sensors or cheaper alternatives? The cheaper ones are known to arrive DOA frequently.

motoxrider365 04-21-2013 04:21 PM

Sorry for the late reply! The sensors just showed up a few days ago! Long shipping time :/

I put my OEM sensors in (replaced BOTH crank and cam with OEM). And not a darn difference. Still throws the same code in the same way as before. So aside from being very discouraged, I tried something else.

I read around that a common fix is to solder the connections...Ok, so I did that too, and not a single change. Still throws the code just as it did before (but it seems to run better).

At this point, unless anyone has any other ideas, I think it's the computer. I can't think of anything else...all my wires are good, no more connections in the way, brand new OEM sensors.

Any thoughts would be greatly appreciated. Thanks for everyone's help up to this point!

-Alex

motoxrider365 04-27-2013 02:52 PM

Ok so ordered a new computer. Put that in...problem is still there. Tried fishing out all the wiring AGAIN, pulling all tape off and everything. Took the harness to computer plug apart, and it broke going back together, so unless anyone has any other ideas, I don't really feel like shelling out for a harness and then trying to figure out what the problem is all over again. I guess I'll be parting it out unless anyone wants it.

It looks like I'll be sticking to imports.

motoxrider365 04-29-2013 08:43 AM

More updates. Found harness ends on ebay. Will be rebuilding harness and checking every single frikin wire on the thing. If it ends up working when I put the harness back on, then great. If not, It would have to be something else. My O2 sensor connector melted together, so I have to fix that. Will probably just get a new sensor since its like 25 bucks.

If the harness work doesn't fix the problem I think it's something non electrical at that point. The PO did engine work, so I have a few questions regarding that. Is it possible for the flywheel to be put on wrong so that the car will receive a poor sensor signal but still wrong? Maybe so that the car is off by half a crank turn? I haven't pulled the trans to look, just peeked through the bell housing where the crank sensor is. The other sensor is at the distributor, so is there any possibility anything could be wrong there? I shook it all and it seems like its solid. I'm looking for anything at this point, so if I could get some ideas here that would be great.

-Thanks

RUBI 4 MY MRS 04-29-2013 12:54 PM

Might look at this link & check your distributor. The pulse ring has to pass very close to the signal generator on the cam sensor. If the shaft has excessive play is can cause an erratic signal. I know you say it is solid but also check the pulse ring for any play.

http://www.wranglerforum.com/f5/p139...et-185181.html

motoxrider365 04-29-2013 01:12 PM

Thanks! I did notice that the ring looked a little funny. I didn't get to compare witha perfect one, but I think it may have an awkward bend it it. I didn't realize it was that sensitive but at this point I feel this car is the most sensitive thing ever! And yet I still can't hate it!

I may just throw a new assembly in there, I'm really quiet exhausted from dealing with it.

As always I'll keep you all posted! I appreciate the response.

motoxrider365 05-13-2013 07:53 AM

Well, I got a new distributor in, and it fixed the problem! Shortly after jumping up and down from the sheer excitement of getting my weekends back (and not dealing with this stupid problem), I was quickly annoyed with the fact it was a 70 dollar fix -_- When I checked the alternator before, it seemed quite secure. When I wiggled it all around OUTSIDE the car, it had a lot more lateral play.

Goes to show ya. So for any of you in the future. I got my distributor (WITH a cam sensor, cap & rotor, and gasket) for about 70 dollars. Personally, I would just friggin buy this bundle as one of the first things to do, because the OEM sensor alone was about 65 bucks...

Thanks to everyone who helped out with advice, and those folks on the internet who wrote other articles/posts. This truly was a pain in the butt with a simple solution.

Now that my Jeep is on the road, I simply cannot be annoyed with it anymore, I love it.

I'll continue to monitor this thread if anyone in the future has any similar problems.

jmetz75 09-13-2013 07:01 AM

everything still running good for you?

I've had the same issues and have fixed to much to list, Jeep is at dealership now and have had no luck, I am telling them to put in a new distributor and praying this is finally it!!

motoxrider365 09-13-2013 07:23 AM

Everything still running perfect for me! I was able to pass emissions and everything. Finally took it out on the trails too, everything is well. Good luck! Let us know how it goes.

jmetz75 10-09-2013 07:47 AM

put in new distributor, ran great on the way home...I felt a slight hesitation a couple times though, the last time I replaced the Cam Sensor it also ran great for 2,3 weeks but with a periodic slight hesitation, then the hesitation got progressively worse until it was so rough it quit running...

fingers crossed

already replaced:
Distributor Cap
Rotor Button
Cam Sensor
Plugs/wires
Crankshaft Position Sensor

now complete Distributor

hopefully this will do it!

Fitzey5435 10-09-2013 08:20 AM

Double check your plugs gapping.

Bransdead 06-18-2014 08:59 PM

Quote:

Originally Posted by motoxrider365 (Post 3750076)
Well, I got a new distributor in, and it fixed the problem! Shortly after jumping up and down from the sheer excitement of getting my weekends back (and not dealing with this stupid problem), I was quickly annoyed with the fact it was a 70 dollar fix -_- When I checked the alternator before, it seemed quite secure. When I wiggled it all around OUTSIDE the car, it had a lot more lateral play.

Goes to show ya. So for any of you in the future. I got my distributor (WITH a cam sensor, cap & rotor, and gasket) for about 70 dollars. Personally, I would just friggin buy this bundle as one of the first things to do, because the OEM sensor alone was about 65 bucks...

Thanks to everyone who helped out with advice, and those folks on the internet who wrote other articles/posts. This truly was a pain in the butt with a simple solution.

Now that my Jeep is on the road, I simply cannot be annoyed with it anymore, I love it.

I'll continue to monitor this thread if anyone in the future has any similar problems.

I'm having these same problems. Replaced with distributor from local pull parts yard and it runs a lot better but still hesitates once in a blue moon. Where did you get a $70 distributor? 98 wrangler 4.0 manual


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