P0340 & P0344

[Duner]

Also have a similar issue going on. Recently did my OPDA, had to realign the timing marks on my crank pulley because I accidentally bumped the socket wrench. Was fine for a few days but the code came back and now I have a cylinder 1 misfire too.

Unfortunately I damaged the CPS when installing my MML. I repaired it but it’s hard to tell what the cause is. It seems to run the same with the crown sensor, yes I know not to use it, just buying time with it.

Misaligned OPDA, bad sensors, or maybe the misfire has to do with it?

 

[sab]

Unfortunately I damaged the CPS when installing my MML. I repaired it...

I saw that post, and that repair looked a bit "finky" to me, no offense intended. I've made repairs like that out of necessity, but I would pot the top of the sensor to protect the fragile wiring. Even then, it would be my last resort. Vehicles are very abusive to fragile wiring.

Misaligned OPDA, bad sensors, or maybe the misfire has to do with it?

Impossible for me to say from a keyboard, but I wouldn't hesitate to try the aftermarket sensor; however, after installation, I'd rotate the ODPA to set the Cam Crank Difference as close to zero as possible, and then I'd do either the Set Sync (for your TJ) or the ReLearn Cam Crank (for your LJ) procedure. Only after that, would I be comfortable in saying the aftermarket sensor is complete junk and useless.

And if you still want to try the repaired sensor, the Set Sync/ReLearn Cam Crank is your friend there, too.

 

[Duner]

I saw that post, and that repair looked a bit "finky" to me, no offense intended. I've made repairs like that out of necessity, but I would pot the top of the sensor to protect the fragile wiring. Even then, it would be my last resort. Vehicles are very abusive to fragile wiring.


Impossible for me to say from a keyboard, but I wouldn't hesitate to try the aftermarket sensor; however, after installation, I'd rotate the ODPA to set the Cam Crank Difference as close to zero as possible, and then I'd do either the Set Sync (for your TJ) or the ReLearn Cam Crank (for your LJ) procedure. Only after that, would I be comfortable in saying the aftermarket sensor is complete junk and useless.

And if you still want to try the repaired sensor, the Set Sync/ReLearn Cam Crank is your friend there, too.

None taken LOL, I knew it was a shotty repair. What does it mean to pot it?

It starts up and runs fine, hopefully a new spark plug fixes the misfire.

By rotating the OPDA do you mean to align the holes that are pinned? I did install the new crown OPDA, and I had it pinned when I aligned the crank timing marks.

I also don’t have the scanner to do the relearn cam crank (it’s an LJ). I read a forum thread and the tool to do is rather expensive unless I’m mistaken.

 

[mudmaster]

I got my CPS from NAPA and haven't had any issues with it so far in 5 months.

 

[sab]

I got my CPS from NAPA and haven't had any issues with it so far in 5 months.

So you've had a bit of luck. Unfortunately, there are a lot of posts where TJ owners didn't have that luck. The point of my posts is to point out that there is a way to deal with a sensor that's a bit "off" - not bad, just off a bit. Rotating the OPDA and using the "Set Sync" or "Relearn" function can significantly increase the chance that your sensor change will be successful. It's not a guarantee of success, though. There are many factors at play. However, whenever I see a post where many things have been tried, but rotating and syncing were not in the mix, I always suggest it.

 

[sab]

What does it mean to pot it?

If you've ever seen an electronic component that's in an open-top housing and appears to be filled with a rubbery substance, you've seen it. Potting is the process of pouring the rubber in:

To do it on a sensor, I rough everything I can up with sandpaper or wire brushes and clean it carefully with acetone (carefully means testing first to make sure the acetone won't react with anything on the sensor.) Then, because there's no housing, I take an aluminum can and cut it so that I have a sheet of thin aluminum. Then I use a release agent on it (basically an oil that prevents the potting compound from sticking to it) and wrap it around the sensor using tape. If it's irregular in shape, I have to get creative. Then, I pour the potting compound in there. Once it cures, I remove the aluminum. The purpose of the potting is to give the wires support.

By rotating the OPDA do you mean to align the holes that are pinned? I did install the new crown OPDA, and I had it pinned when I aligned the crank timing marks.

No. If you look at the OPDA, you'll see that if you loosen the hold-down screw for the OPDA housing, you can then rotate it, and doing so changes the timing of the target wheel inside the OPDA relative to the camshaft, and since the cam and crank are joined by the timing chain and sprockets (at a 1 to 2 ratio), you are also changing the timing between the cam signal pulses and the crank signal pulses. What usually happens when it's not right is that one of the cam pulses moves to the other side of a crank pulse, screwing up the PCM's understanding of where the crank is (relative to top dead center) because it is expecting to see a certain number of crank pulses between the cam pulses.

In the figure below, taken from Chrysler's "NGC and GPEC Speed Density Fuel Systems" tech manual, the cam pulses are up top and the crank pulses are below that. The PCM is counting both, relative to a clock. If any are out of place, a DTC will eventually be generated. Additionally, the PCM's clock is so accurate that it measures the time between some of the pulses. As each cylinder fires, there is a small acceleration of the crank. Misfires result in one of the measured time periods being slightly longer than it should be because the cylinder not firing results in no acceleration which increase the time to rotate a few degrees. If enough of these slow time periods get measured, one of the 03XX codes is triggered.

 

[Duner]

If you've ever seen an electronic component that's in an open-top housing and appears to be filled with a rubbery substance, you've seen it. Potting is the process of pouring the rubber in:
View attachment 602736

To do it on a sensor, I rough everything I can up with sandpaper or wire brushes and clean it carefully with acetone (carefully means testing first to make sure the acetone won't react with anything on the sensor.) Then, because there's no housing, I take an aluminum can and cut it so that I have a sheet of thin aluminum. Then I use a release agent on it (basically an oil that prevents the potting compound from sticking to it) and wrap it around the sensor using tape. If it's irregular in shape, I have to get creative. Then, I pour the potting compound in there. Once it cures, I remove the aluminum. The purpose of the potting is to give the wires support.


No. If you look at the OPDA, you'll see that if you loosen the hold-down screw for the OPDA housing, you can then rotate it, and doing so changes the timing of the target wheel inside the OPDA relative to the camshaft, and since the cam and crank are joined by the timing chain and sprockets (at a 1 to 2 ratio), you are also changing the timing between the cam signal pulses and the crank signal pulses. What usually happens when it's not right is that one of the cam pulses moves to the other side of a crank pulse, screwing up the PCM's understanding of where the crank is (relative to top dead center) because it is expecting to see a certain number of crank pulses between the cam pulses.

In the figure below, taken from Chrysler's "NGC and GPEC Speed Density Fuel Systems" tech manual, the cam pulses are up top and the crank pulses are below that. The PCM is counting both, relative to a clock. If any are out of place, a DTC will eventually be generated. Additionally, the PCM's clock is so accurate that it measures the time between some of the pulses. As each cylinder fires, there is a small acceleration of the crank. Misfires result in one of the measured time periods being slightly longer than it should be because the cylinder not firing results in no acceleration which increase the time to rotate a few degrees. If enough of these slow time periods get measured, one of the 03XX codes is triggered.

View attachment 602738

It’s strange how it could seemingly run fine for a few days then have the codes thrown. Mine are specifically 0344 and 0301. I’m hoping the misfire is directly related to the cam sensor. I’m picking up the Napa sensor tomorrow, I’ll see if that fixes it. If not I could try to redo the timing alignment.

 

[sab]

It’s strange how it could seemingly run fine for a few days then have the codes thrown. Mine are specifically 0344 and 0301. I’m hoping the misfire is directly related to the cam sensor. I’m picking up the Napa sensor tomorrow, I’ll see if that fixes it. If not I could try to redo the timing alignment.

First off, this is your LJ, right? P0344 is not a possible code listed for the JTEC PCM in your 2003, but it is for the NGC PCM in your LJ, so that's why I'm assuming it's your LJ. Anytime I get P0335, P0339, P0340, or P0344 (which are signal issues with the crankshaft and camshaft position signals) combined with any of the P0300 through P0306 codes, the P0300-P0306 is likely to have been caused by the problem that triggered the P0335-P0344 code, so I'd start my investigation with the P0344 code.

Here's the section on P0344 from the Powertrain Diagnostic Procedures Manual (I've circled some important things):

The top part I circled may explain why "it could seemingly run fine for a few days then have the codes thrown." With an intermittent problem, it could take many trips before you had one where 20 events were observed by the PCM. The Powertrain Diagnostic Procedures Manual is a bit vague in explaining how intermittent codes are handled, so I'm not sure what the process is for the PCM to determine when to light the DTC light.

In the Possible Causes box, there are five I circled that could have something to do with your repair (assuming that you are running that repaired camshaft position sensor). In the sequence of photos you posted, you went from this:

To this:

You probably didn't, but if you left the red (+5V Supply) and black (GND) conductors exposed and just wrapped the entire assembly in electrical tape, vibration could be allowing the two conductors to touch every so often. When they do, the first "Possible Cause" that I circled (+5V short to GND) will occur.

In your case, I think your plan is solid. Replace that sensor to rule out the shorting. I always recommend rotating the OPDA and performing a Relearn when changing a camshaft position sensor because it's not very difficult, and it rules out that being a cause for code generation. Also, since it was discovered that disconnecting the battery will force the PCM to do the Relearn on the next startup, a bidirectional scanner may not be required. You just need a scanner that can monitor the Cam Crank Difference variable while you rotate the OPDA.

Good Luck!

 

[sgesbeck]

To reiterate my last post, if you don't have Mopar sensors, that action alone may not be successful. Aftermarket sensors are not built as precisely and often require a manual rotation of the OPDA while monitoring the "Cam Crank Difference" variable in the datastream to set that variable as close to zero as possible. It's explained more in that thread (see the "If You Rotate Your OPDA" section in the first post).

Edited to add: With the quality of everything in the toilet these days, even a Mopar sensor may require a manual rotation to get it to work.

SAB - I don't currently have a scan tool with the cam/crank difference function or I would have done as you suggested. I figured I'd try the PCM relearn procedure as a first step since it is ridiculously easy. If the code comes back I'll invest in either the AutelMK808 or the ThinkDiag2 tools as I saw both provide the necessary function for manual rotation.

After doing the relearn yesterday, I let the Jeep idle for about 15 minutes while I got my hiking gear together. I drove about 25 miles up the canyon with no issues. Before starting the hike I verified there were no confirmed or pending codes. After about 6 hours I got back to Jeep and drove home and no issues. Confirmed when I got home no confirmed or pending codes.

I really hope this is it. Appreciate the excellent support this forum provides!

 

[Duner]

First off, this is your LJ, right? P0344 is not a possible code listed for the JTEC PCM in your 2003, but it is for the NGC PCM in your LJ, so that's why I'm assuming it's your LJ. Anytime I get P0335, P0339, P0340, or P0344 (which are signal issues with the crankshaft and camshaft position signals) combined with any of the P0300 through P0306 codes, the P0300-P0306 is likely to have been caused by the problem that triggered the P0335-P0344 code, so I'd start my investigation with the P0344 code.

Here's the section on P0344 from the Powertrain Diagnostic Procedures Manual (I've circled some important things):
View attachment 602928

The top part I circled may explain why "it could seemingly run fine for a few days then have the codes thrown." With an intermittent problem, it could take many trips before you had one where 20 events were observed by the PCM. The Powertrain Diagnostic Procedures Manual is a bit vague in explaining how intermittent codes are handled, so I'm not sure what the process is for the PCM to determine when to light the DTC light.

In the Possible Causes box, there are five I circled that could have something to do with your repair (assuming that you are running that repaired camshaft position sensor). In the sequence of photos you posted, you went from this:
View attachment 602933

To this:
View attachment 602935

You probably didn't, but if you left the red (+5V Supply) and black (GND) conductors exposed and just wrapped the entire assembly in electrical tape, vibration could be allowing the two conductors to touch every so often. When they do, the first "Possible Cause" that I circled (+5V short to GND) will occur.

In your case, I think your plan is solid. Replace that sensor to rule out the shorting. I always recommend rotating the OPDA and performing a Relearn when changing a camshaft position sensor because it's not very difficult, and it rules out that being a cause for code generation. Also, since it was discovered that disconnecting the battery will force the PCM to do the Relearn on the next startup, a bidirectional scanner may not be required. You just need a scanner that can monitor the Cam Crank Difference variable while you rotate the OPDA.

Good Luck!

Responses like this are what make me glad this forum exists. I appreciate the level of detail you go to, very well put. The sensor wiring could definitely do it. Even with the crown sensor, which I know is not good, could be the source too. I read your posts on another thread and I ended up purchasing the thinkdiag2 since I don’t have a way to measure the angle of the cam.

I could just loosen it and guess to get it right but honestly I’d rather take the guesswork out. It’s coming in tomorrow so I’ll report back with what I find.

 

[sab]

Responses like this are what make me glad this forum exists.

And remember - coming back to confirm things is also important for adding value to the forum's content. In fact, I'd suggest also adding a post in the Using the DRBIII... thread, too, so others can benefit from your experience.

 

[Duner]

And remember - coming back to confirm things is also important for adding value to the forum's content. In fact, I'd suggest also adding a post in the Using the DRBIII... thread, too, so others can benefit from your experience.

Got the thinkdiag2 and I’m having issues. It’s saying my vin is not supported. Have you seen this issue before?

Update: do the vin scan then look for the Chrysler/dodge/jeep vehicle package, it originally didn’t show up when first setting up the app.

 

[Duner]

@sab great news, I got this thing dialed in, it seems to fluctuate between 6553.50 (-0.1) and 0.1, which as far as I’m aware is spot on. See the picture for my original difference values, YIKES! My CEL is gone now.

Couldn’t seem to get the relearn to work in the app or with disconnecting the negative terminal and connecting it to hot at first, wasn’t sure if it was an instant change or not, after idling for a few minutes it worked! I owe you a beer

 

[sab]

@sab great news, I got this thing dialed in, it seems to fluctuate between 6553.50 (-0.1) and 0.1, which as far as I’m aware is spot on. See the picture for my original difference values, YIKES! My CEL is gone now.

That's great news, Duner! Let's hope it stays gone. As you noted previously, it sometimes takes a while for it to show up.

 

[Duner]

That's great news, Duner! Let's hope it stays gone. As you noted previously, it sometimes takes a while for it to show up.

Took it for a drive and after about 45 minutes the CEL came back on for p301. Initially left in crown, swapped to the Napa and it’s still there.

Is there other data I can read on the thinkdiag2 to trouble shoot?. I do know I have an exhaust manifold leak, but I think that is at the very back which would be cylinder 6.

After relearning the napa and letting it file now I’m getting p0300 and p0301. It seems to start and idle fine. I did find a screen that shows misfire data. You can see the count for cyl1 is high, then all of a sudden it’s back to zero again?

After all this I replaced the spark plug for in cylinder 1 (forward most) misfire still present.

 

[sab]

Took it for a drive and after about 45 minutes the CEL came back on for p301. Initially left in crown, swapped to the Napa and it’s still there.

If the only codes you're getting are misfire codes, it's not likely to be caused by a crank or cam position sensor, especially if you are getting actual misfires. I would expect to see a code for a cam or crank position sensor if they were the root cause. I wouldn't change the sensors; rather, start investigating your misfire.

After relearning the napa and letting it file now I’m getting p0300 and p0301. It seems to start and idle fine. I did find a screen that shows misfire data. You can see the count for cyl1 is high, then all of a sudden it’s back to zero again?

All I know about PCM logic is what I've been able to read in the documents I've found. I don't know how the PCM handles the misfire counters, unfortunately. Misfires can be a frustrating issue to diagnose because there are many causes, and many are hard to test. At this point, the only advice I can give is to refer to the Possible Causes chart and the Test Table following it for P030X in the Powertrain Diagnostic Procedures Manual (see download link in second paragraph of Post #28.)

 

[Duner]

I’ll look into this after work! Thanks for that link. I did replace the spark plug with a ngk ZFR5N, no change was noticed. Next I was thinking to borrow my dad’s ignition coil pack since that’s an easy test.

If that’s the issue I may snag the viper coil block that’s been suggested, seems like the consensus was quality aftermarket coil packs, same design as OEM, are hard to come by.

 

[Duner]

@sab swapped the coil pack from my dad’s onto mine during lunch, still having a misfire but I confirmed a suspicion I had. The misfire only seems to occur while at lower RPM, 1000 or less. It seemed like the counter would wipe to zero when going from lower to higher rpms. While at higher rpms no misfires were occuring. Also noticed misfires on other cylinders (see pic), but these were a lot less frequent and did not consistently occur like cylinder 1, hard to say if that’s an issue with the swapped in coil pack or not, because I did have p0300 temporarily before with my coil pack in. I took that screenshot as soon as I slowed down to park and cyl1 misfires instantly skyrocketed.

The misfires also did not start occurring until the engine got warmer, cold start it had no misfires.

 

[JKP]

I’ll look into this after work! Thanks for that link. I did replace the spark plug with a ngk ZFR5N, no change was noticed. Next I was thinking to borrow my dad’s ignition coil pack since that’s an easy test.

If that’s the issue I may snag the viper coil block that’s been suggested, seems like the consensus was quality aftermarket coil packs, same design as OEM, are hard to come by.

Blue Streak by Standard Ign is a good OEM style coil pack if needed.

 

[Duner]

Update, looks like the misfiring has stopped. Im not super familiar with the logic of the PCM, but it seems it took a bit of driving to adjust to the swapped in coil pack.

Unless cold ambient air (~30 degrees) or the misfire counter feature on the thinkdiag is bugged, I think my issue is fixed… knock on wood!