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To anyone with more technical knowledge or who has serviced GM’s, are you familiar with the crank position relearning procedure for vehicles equipped with a 24X crank sensor? I did replace the harmonic balancer. The 24X sensor was simply cleaned and reinstalled. Would this possibly cause an issue requiring a relearning procedure as described below? I’ve posted part of an article. Thanks for your time…
Partial Text: DTC P1336 CKP System Variation Not Learned from GM Factory Service Manual
The following text is quoted from the 1999 GM F-Body Factory Service Manual:
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Circuit DescriptionThe Crankshaft Position (CKP) sensor sends pulses to the PCM as the reluctor wheel teeth rotate past the CKP sensor. The PCM uses the CKP pulses to synchronize the ignition and fuel injector operation, and to time the interval between each CKP pulse. The PCM determines when an excessive change in crankshaft speed occurs by comparing each new time interval with the previous interval. A misfire causes an unexpected change in the crankshaft speed. A certain amount of acceleration/deceleration is expected between each firing stroke, but if the crankshaft speed changes more then an expected amount, the PCM interprets this as a misfire. The interval between the CKP sensor pulses is extremely small. At high engine speeds, slight variations in the following components make misfire detection difficult: Crankshaft, Reluctor wheel, CKP sensor. The PCM learns variations during the Crankshaft Position System Variation Learning Procedure. The PCM compensates for these variations when performing detect misfire calculations. Only a scan tool can command the PCM to perform the Crankshaft Position Variation Learning Procedure again.
Perform the learning procedure after the following actions: A PCM replacement, Any operation or repair involving the crankshaft, the CKP sensor, or the CKP to reluctor wheel gap relationship, An engine replacement, The ignition switch is in the ON position until the battery is drained.
Important: A PCM power-disconnect with the ignition ON may erase the stored pulse value and set the DTC P1336. Disconnecting the PCM will not erase the learned Crankshaft Position System Variation as long as the ignition switch is in the OFF position.
Important: Reprogramming the PCM does not require running the Crankshaft Position System Variation Learn Procedure unless the PCM is new or from another vehicle. A DTC P1336 sets if the Crankshaft Position System Variation is not within an acceptable range, or can not be learned.
To anyone with more technical knowledge or who has serviced GM’s, are you familiar with the crank position relearning procedure for vehicles equipped with a 24X crank sensor? I did replace the harmonic balancer. The 24X sensor was simply cleaned and reinstalled. Would this possibly cause an issue requiring a relearning procedure as described below? I’ve posted part of an article. Thanks for your time…
Partial Text: DTC P1336 CKP System Variation Not Learned from GM Factory Service Manual
The following text is quoted from the 1999 GM F-Body Factory Service Manual:
“
Circuit DescriptionThe Crankshaft Position (CKP) sensor sends pulses to the PCM as the reluctor wheel teeth rotate past the CKP sensor. The PCM uses the CKP pulses to synchronize the ignition and fuel injector operation, and to time the interval between each CKP pulse. The PCM determines when an excessive change in crankshaft speed occurs by comparing each new time interval with the previous interval. A misfire causes an unexpected change in the crankshaft speed. A certain amount of acceleration/deceleration is expected between each firing stroke, but if the crankshaft speed changes more then an expected amount, the PCM interprets this as a misfire. The interval between the CKP sensor pulses is extremely small. At high engine speeds, slight variations in the following components make misfire detection difficult: Crankshaft, Reluctor wheel, CKP sensor. The PCM learns variations during the Crankshaft Position System Variation Learning Procedure. The PCM compensates for these variations when performing detect misfire calculations. Only a scan tool can command the PCM to perform the Crankshaft Position Variation Learning Procedure again.
Perform the learning procedure after the following actions: A PCM replacement, Any operation or repair involving the crankshaft, the CKP sensor, or the CKP to reluctor wheel gap relationship, An engine replacement, The ignition switch is in the ON position until the battery is drained.
Important: A PCM power-disconnect with the ignition ON may erase the stored pulse value and set the DTC P1336. Disconnecting the PCM will not erase the learned Crankshaft Position System Variation as long as the ignition switch is in the OFF position.
Important: Reprogramming the PCM does not require running the Crankshaft Position System Variation Learn Procedure unless the PCM is new or from another vehicle. A DTC P1336 sets if the Crankshaft Position System Variation is not within an acceptable range, or can not be learned.
Fredsmythson, I’m thinking again about your reply. Does any of this sound familiar?
* Sometimes the car will run very smooth initially at idle, until it warms up a bit.
* Other times, the car will skip some and idle rough when first cranked.
* The ‘loping’ previously described doesn’t always occur, but happens occasionally, usually when engine is fully warm.
* I can sometimes make the problem temporarily disappear by raising the rpm’s.
* The car generally hesitates upon take off, but not always.
* The car misses throughout the driving range, but less often at interstate speeds.
* The problem is more apparent at lower speeds and in traffic.It does act like a vacuum leak. However, I’ve been unable to find it.I did change the harmonic balancer during my repair work, as the old one was bad. The crank sensor was taken off, cleaned and replaced. Anyways, I’m curious as to whether any of the symptoms above we’re experienced when you had the problem with the Lumina. As Eric advises, I don’t like to throw parts at a car. However, nothing is making sense right now. Btw, I once drove a 90 and 92 Lumina years ago as company cars..I really enjoyed them. Thanks should you have time to respond.
Fredsmythson, I’m thinking again about your reply. Does any of this sound familiar?
* Sometimes the car will run very smooth initially at idle, until it warms up a bit.
* Other times, the car will skip some and idle rough when first cranked.
* The ‘loping’ previously described doesn’t always occur, but happens occasionally, usually when engine is fully warm.
* I can sometimes make the problem temporarily disappear by raising the rpm’s.
* The car generally hesitates upon take off, but not always.
* The car misses throughout the driving range, but less often at interstate speeds.
* The problem is more apparent at lower speeds and in traffic.It does act like a vacuum leak. However, I’ve been unable to find it.I did change the harmonic balancer during my repair work, as the old one was bad. The crank sensor was taken off, cleaned and replaced. Anyways, I’m curious as to whether any of the symptoms above we’re experienced when you had the problem with the Lumina. As Eric advises, I don’t like to throw parts at a car. However, nothing is making sense right now. Btw, I once drove a 90 and 92 Lumina years ago as company cars..I really enjoyed them. Thanks should you have time to respond.
Gents, I didn’t get super far along with trouble shooting today. However, I did try a couple things. Per EricThe Car guys suggestion, I bought a spill free funnel and bled the system…made a mess first time I used it..lol…nothing like reading instructions. After purging air, I also cleaned the MAF sensor and reinstalled it. The engine finally threw a code PO 440. That code would come on periodically before the engine work, so may not tell me anything… I’ll do a proper power balance test soon. I did unplug cylinders 2, 4 and 6 at the spark plug. Also, I was unable to find any vacuum leaks. Will smoke test it first part of the week. Thanks Eric for your helpful post…Will keep you guys apprised as I continue the good fight 🙂 thanks to all for help…
Gents, I didn’t get super far along with trouble shooting today. However, I did try a couple things. Per EricThe Car guys suggestion, I bought a spill free funnel and bled the system…made a mess first time I used it..lol…nothing like reading instructions. After purging air, I also cleaned the MAF sensor and reinstalled it. The engine finally threw a code PO 440. That code would come on periodically before the engine work, so may not tell me anything… I’ll do a proper power balance test soon. I did unplug cylinders 2, 4 and 6 at the spark plug. Also, I was unable to find any vacuum leaks. Will smoke test it first part of the week. Thanks Eric for your helpful post…Will keep you guys apprised as I continue the good fight 🙂 thanks to all for help…
Thanks Fredsmythson or your reply. When your crankshaft position sensor malfunctioned did it generate a trouble code? My car hasn’t, which is part of the challenge. The set up on this vehicle actually uses two crank sensors. I did replace the harmonic balancer and seal. Also, I had to remove the sensor near the balancer when I replaced the timing chain. I thoroughly cleaned it before reinstall. None of these symptoms were present before the repair. I’ll keep you posted on this. I’m leaning away from this a bit, as the problem wasn’t present before repair. Thanks again…
Thanks Fredsmythson or your reply. When your crankshaft position sensor malfunctioned did it generate a trouble code? My car hasn’t, which is part of the challenge. The set up on this vehicle actually uses two crank sensors. I did replace the harmonic balancer and seal. Also, I had to remove the sensor near the balancer when I replaced the timing chain. I thoroughly cleaned it before reinstall. None of these symptoms were present before the repair. I’ll keep you posted on this. I’m leaning away from this a bit, as the problem wasn’t present before repair. Thanks again…
OneDTwenty Thanks for your reply.
There is no history of overheat. I went into the engine due to the presence of coolant in the oil. The intake gaskets on these 3.4 engines are notorious for leaking.
This vehicle does not use a distributor. It’s equipped with a DIS system utilizing 3 coils.
I am sure the timing is right…
I have not pressure checked the cooling system. That is a good suggestion.
We’re in the Southeast storm. So it may be a few days… I’ll keep you posted..thanks again..
OneDTwenty Thanks for your reply.
There is no history of overheat. I went into the engine due to the presence of coolant in the oil. The intake gaskets on these 3.4 engines are notorious for leaking.
This vehicle does not use a distributor. It’s equipped with a DIS system utilizing 3 coils.
I am sure the timing is right…
I have not pressure checked the cooling system. That is a good suggestion.
We’re in the Southeast storm. So it may be a few days… I’ll keep you posted..thanks again..
Valde, thanks for the tip. This is a bit beyond my skill level. My scanner is a cheapo that simply reads and clears OBD 2 trouble codes. Next Tuesday, I plan to take the van to a friend’s shop who will have a real scanner and proficient skill-knowledge. I’ll certainly take your suggestions with me. I’ll keep you posted…
Valde, thanks for the tip. This is a bit beyond my skill level. My scanner is a cheapo that simply reads and clears OBD 2 trouble codes. Next Tuesday, I plan to take the van to a friend’s shop who will have a real scanner and proficient skill-knowledge. I’ll certainly take your suggestions with me. I’ll keep you posted…