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I recently had my car in the shop to replace my alternator. My new alternator is working great however afterwards I started getting a P0339 Crankshaft Position Sensor code being thrown. I had the sensor replaced with a new one and while it seems better now, I'm still having problems.

I've been making several test drives to try and diagnose.

After clearing the code it seems that as long as I let the car warm up to full temp the car will run great without any issues. Even when the car hasn't quiet warmed up yet, it idles great and will even run great as long as I keep it under 2k. If the car isn't fully warm yet and I get it over 2k it bucks, takes away power, and forces me to drive under 2k (limp mode) and then it throws the code again. I clear the code and all is good again as long as the car is warm.

Any theories on what the problem could be and why it would only seem to happen before I get the car up to at least 190 degrees?
 

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I recently had my car in the shop to replace my alternator. My new alternator is working great however afterwards I started getting a P0339 Crankshaft Position Sensor code being thrown. I had the sensor replaced with a new one and while it seems better now, I'm still having problems.

I've been making several test drives to try and diagnose.

After clearing the code it seems that as long as I let the car warm up to full temp the car will run great without any issues. Even when the car hasn't quiet warmed up yet, it idles great and will even run great as long as I keep it under 2k. If the car isn't fully warm yet and I get it over 2k it bucks, takes away power, and forces me to drive under 2k (limp mode) and then it throws the code again. I clear the code and all is good again as long as the car is warm.

Any theories on what the problem could be and why it would only seem to happen before I get the car up to at least 190 degrees?
What prompted you to have the alternator replaced? The alternator may in fact be working just fine but the problem attributed to the alternator may be due to something else and the crankshaft position sensor error the inability to run above 2K when not warm arise from this something else.

I have never had an engine refuse to run right above 2K RPMs regardless of how cold it was. I would never push an engine to much higher RPMs -- generally 3K is my "limit" but with some cars the automaker guidelines call for RPMs to be kept below 4K -- but 2K is "safe" when the engine is cold.

That trouble running above 2K could be a fuel supply (or pressure) problem or possibly -- I have seen this before with another brand of car -- insufficient electrical power. As I touched upon above while you replaced the alternator assuming the new alternator is working 100% this did not address the problem.
 

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In a lot of cases with failed alternators, the PCM ended up being replaced also. This is because the PCM acts as the voltage regulator. A diode block failure can feedback AC (alternating current) back on the PWM (pulse width modulated) signal and wreak havoc withe the circutry in the PCM causing a myriad of strange problems. One of them is being discussed here already.
-John
 

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In a lot of cases with failed alternators, the PCM ended up being replaced also. This is because the PCM acts as the voltage regulator. A diode block failure can feedback AC (alternating current) back on the PWM (pulse width modulated) signal and wreak havoc withe the circutry in the PCM causing a myriad of strange problems. One of them is being discussed here already.
-John
Good point.

While in some cases the alternator contains the voltage regulator in the case of I guess Dodge it is as you say, the PCM plays this role or part of it.

Thus insufficient voltage may be due to a bad alternator but it can be bad, or may appear to be bad, because the voltage regulation provided for by the PCM is wrong.

If for whatever reason the voltage needs of the car's electrical system is not being met this can result in all kinds of untoward behavior. Certainly not running right at higher RPMs could be one example of such behavior.
 

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What prompted you to have the alternator replaced? The alternator may in fact be working just fine but the problem attributed to the alternator may be due to something else and the crankshaft position sensor error the inability to run above 2K when not warm arise from this something else.

I have never had an engine refuse to run right above 2K RPMs regardless of how cold it was. I would never push an engine to much higher RPMs -- generally 3K is my "limit" but with some cars the automaker guidelines call for RPMs to be kept below 4K -- but 2K is "safe" when the engine is cold.

That trouble running above 2K could be a fuel supply (or pressure) problem or possibly -- I have seen this before with another brand of car -- insufficient electrical power. As I touched upon above while you replaced the alternator assuming the new alternator is working 100% this did not address the problem.
It's not always limiting at 2k or running bad above 2k, it only bucks randomly above 2k and then once it throws that code it goes limp mode and won't let me drive above 2k again until I reset the code. Even when in limp mode it runs fine just won't let me over 2k.
 

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In a lot of cases with failed alternators, the PCM ended up being replaced also. This is because the PCM acts as the voltage regulator. A diode block failure can feedback AC (alternating current) back on the PWM (pulse width modulated) signal and wreak havoc withe the circutry in the PCM causing a myriad of strange problems. One of them is being discussed here already.
-John
It was definitely a bad alternator. It was whining. It wasn't charging at all. And even test it for charging. I no longer have charging problems after nthe new alternator.
 

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Discussion Starter #9
Good point.

While in some cases the alternator contains the voltage regulator in the case of I guess Dodge it is as you say, the PCM plays this role or part of it.

Thus insufficient voltage may be due to a bad alternator but it can be bad, or may appear to be bad, because the voltage regulation provided for by the PCM is wrong.

If for whatever reason the voltage needs of the car's electrical system is not being met this can result in all kinds of untoward behavior. Certainly not running right at higher RPMs could be one example of such behavior.
Any ways to really test for something like this from home or on the road?
 

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I'm not saying you're wrong, I'm jus curious , Other than me mentioning about the temps, how would bad thermostat cause the buxki and throwing of the crankshaft sensor code?
My thinking was based on incorrect engine temperatures (erratic thermostat or temp sensor or both) might affect the PCM (fuel & air adjustments) causing the PCM to think the engine was in the normal operating range, when in fact the engine was still cold. ...Wasn't to long ago, all you needed was fuel, spark and air. You still do, but add to the equation that 10 or more computer modules working in perfect harmony make that happen today. One more question. What year and model is your Challenger (engine, transmission, mileage)? That basic information just might bring other members on board with a possible solution.
 

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Any ways to really test for something like this from home or on the road?
All I have relied upon in the past for "testing" the altenator is working right -- is to check the battery voltage -- using a volt meter -- with the engine running and confirming the battery voltage is where it should be. This is in the 13.8V to 14.2V range. But it can vary some. Depends upon the state of the battery and what electrical loads the car might have.

With the presence of a battery voltage gauge in the car I just check that every once in a while. I try to develop a sense of what is normal with the car and then I look for the abnormal.
 

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Discussion Starter #12
I've now replaced the Crankshaft Position Sensor, the Thermostat, and the Coolant Temp sensor and I still experience the same problem. Car runs great when it is up to at least 190 degrees. Below 190 degrees it runs find unless I get the RPMs up above 2500 RPM and at that point if I do, it cuts out, throws the Crankshaft Position Sensor code and the car goes into a limp mode where it won't let me drive over 2000 RPM, but even then below the 2000 it runs/idles fine.
 

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I've now replaced the Crankshaft Position Sensor, the Thermostat, and the Coolant Temp sensor and I still experience the same problem. Car runs great when it is up to at least 190 degrees. Below 190 degrees it runs find unless I get the RPMs up above 2500 RPM and at that point if I do, it cuts out, throws the Crankshaft Position Sensor code and the car goes into a limp mode where it won't let me drive over 2000 RPM, but even then below the 2000 it runs/idles fine.
Not convinced the crankshaft position sensor is the problem, but since there is a crankshaft position sensor error code let me spend some time on the crankshaft position sensor:

The crankshaft position sensor (Hall effect sensor) is sensitive to the gap between the sensor and the tabs on the ring bolted to the flywheel. IIRC with some cars there is a gap dimension called out. If the sensor or sensor mount have no adjustment then the correct gap is apparently obtained by just bolting the sensor (factory sensor) in place.

The problem does not have to be with the sensor. The problem can be with the wiring harness or even the PCM. It is important to check the wring harness for any signs of abrasion, heat damage, or rodent damage. I do not recall the history of the car but any time a wiring harness is disturbed there is always the risk of damaging this. The damage does not have to be "obvious". Too rough handlng can cause copper wiring to break. I was always impressed by how "gentle" techs were when handing wiring harnesses. Especially with older vehicles.

The condition of the electrical connector at the harness is important too. A new sensor's connector should be in good condition -- but is always a good idea to carefully check it for an debris or anything that could interfere with a proper secure connection and to compare it to the old one to see if there are any differences. Also, the check the connector at the wiring harness for anything out of the ordinary.

In some cases problems with the sensor can be ID'd by observing the sensor electrical signal with an analog scope.Often the details are covered in the factory manual that covers OBD2 problems, diagnosis and repair.

It might be of value to observe this signal when the engine runs right then doesn't. Ideally it would also be of value to be able to know what the PCM "thought" of the signal (so to speak). One concern is the PCM is rejecting an otherwise healthy sensor signal due to a problem with the PCM and the input to which the sensor is connected.

It is one thing to when a crankshaft position sensor error is logged to replace the sensor. If this fixes the problem, that's great.

But if not then the investigation gets more complicated. The circuit starting at the wiring harness sensor connector and running all the way back to the PCM is suspect. And even the PCM is suspect as well.

That's all for now on the sensor.

Have you monitored voltage to ensure the alternator is producing sufficient electrical power? The 2K RPM limit does not "feel" like something related to the sensor but to something else with electrical power being high on my list of possible causes.
 

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Discussion Starter #14
Not convinced the crankshaft position sensor is the problem, but since there is a crankshaft position sensor error code let me spend some time on the crankshaft position sensor:

The crankshaft position sensor (Hall effect sensor) is sensitive to the gap between the sensor and the tabs on the ring bolted to the flywheel. IIRC with some cars there is a gap dimension called out. If the sensor or sensor mount have no adjustment then the correct gap is apparently obtained by just bolting the sensor (factory sensor) in place.

The problem does not have to be with the sensor. The problem can be with the wiring harness or even the PCM. It is important to check the wring harness for any signs of abrasion, heat damage, or rodent damage. I do not recall the history of the car but any time a wiring harness is disturbed there is always the risk of damaging this. The damage does not have to be "obvious". Too rough handlng can cause copper wiring to break. I was always impressed by how "gentle" techs were when handing wiring harnesses. Especially with older vehicles.

The condition of the electrical connector at the harness is important too. A new sensor's connector should be in good condition -- but is always a good idea to carefully check it for an debris or anything that could interfere with a proper secure connection and to compare it to the old one to see if there are any differences. Also, the check the connector at the wiring harness for anything out of the ordinary.

In some cases problems with the sensor can be ID'd by observing the sensor electrical signal with an analog scope.Often the details are covered in the factory manual that covers OBD2 problems, diagnosis and repair.

It might be of value to observe this signal when the engine runs right then doesn't. Ideally it would also be of value to be able to know what the PCM "thought" of the signal (so to speak). One concern is the PCM is rejecting an otherwise healthy sensor signal due to a problem with the PCM and the input to which the sensor is connected.

It is one thing to when a crankshaft position sensor error is logged to replace the sensor. If this fixes the problem, that's great.

But if not then the investigation gets more complicated. The circuit starting at the wiring harness sensor connector and running all the way back to the PCM is suspect. And even the PCM is suspect as well.

That's all for now on the sensor.

Have you monitored voltage to ensure the alternator is producing sufficient electrical power? The 2K RPM limit does not "feel" like something related to the sensor but to something else with electrical power being high on my list of possible causes.
This was a very good explanation and thank you for taking the time of such a lengthy writeup. But I'm curious, how would you theorize how what seems to be very precise threshold of 190 degree temperature seems to be factor? Remember it seems that above 190 degrees the car has no issues at all and won't throw the sensor code, no matter how high the RPMS go. It only seems to be when the car is running below that 190 degree mark that the code throws at 2500k RPMS.
 

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This was a very good explanation and thank you for taking the time of such a lengthy writeup. But I'm curious, how would you theorize how what seems to be very precise threshold of 190 degree temperature seems to be factor? Remember it seems that above 190 degrees the car has no issues at all and won't throw the sensor code, no matter how high the RPMS go. It only seems to be when the car is running below that 190 degree mark that the code throws at 2500k RPMS.
My inclination would be to try to obtain independent confirmation of the temperature.

If the behavior is really tied to 190F all I can offer is something involved that is temperature sensitive and when you see 190F the failing component has obtained its failing temperature which I would hazard a guess is probably higher than 190F.
 

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At 190 Deg. F, a new set of operational fuel maps is loaded. This is NOT (normal operating temp.) range. I suspect there is some corruption and it all goes back to the bad alternator and possible bad PCM. I would disconnect the battery and short the battery cables together and hold for 10 seconds to short all the memory capacitors. Reconnect and see what happens. If it is fixed, enjoy! If not, that PCM may be hosed.
-John
 

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At 190 Deg. F, a new set of operational fuel maps is loaded. This is NOT (normal operating temp.) range. I suspect there is some corruption and it all goes back to the bad alternator and possible bad PCM. I would disconnect the battery and short the battery cables together and hold for 10 seconds to short all the memory capacitors. Reconnect and see what happens. If it is fixed, enjoy! If not, that PCM may be hosed.
-John
That could certainly explain why the bad happens right at 190F.
 
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