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Crankshaft relearn


ccgoodwrench

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Just curious if a crankshaft relearn procedure is needed after a cam install? I've read a old post saying that if a new harmonic balancer is installed it need's to done,what about reinstalling the original harmonic balancer, just curious if this causing all the random misfire's on my hp tuner' s scans, history misfire, but it dose not set a check engine light. Hope this make's any sense to anybody, thanks chris

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I found this old post not sure how true it is,A crankshaft variation relearn

must be performed if:

A diagnostic trouble code of P1336 is

present.

 

The computer has been replaced or

re-programmed.

 

The crankshaft position sensor has been

replaced.

 

The engine, harmonic balancer, clutch, or

flywheel have been: disassembled,

removed, or replaced.

 

The crankshaft position variation

learning feature enables the

computer to compensate for part

manufacturing tolerances. This allows the computer to accurately

detect an engine misfire throughout

the engine RPM range. The learning

process is stored in the computers

memory and does not have to be

repeated unless one or more of the

above conditions are present.

 

Some scanners are capable of doing this. Check local garages.

Anyone with HPtuners or EFI Live tuning software can do this also. I found this on gm trucks.com

Edited by ccgoodwrench (see edit history)
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Hey mark how are you doing? did you mean retune? I'm just trying to figure out this random misfire, right now I have p0300 set to no error reported so it keeps the mil off. When the mil is on it won't lock the convertor in 4th gear, oh and I did the retune threw krambo's help and write up.

Edited by ccgoodwrench (see edit history)
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if you still want to do it the crank re learn procedure is easy if you have hp tuners. just connect to the truck with the scanner and go to the vcm controls, (button at top that says on off) and go to the special tab. you will see it there and it will tell you what to do

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Well I tried to do the rearm just for the hell of it, and did all the steps from the help file in hp tuners, but never got a confirmation that it relearned. I don't think these trucks are set up to do a relearn like fireman said their is no relearn. Now that I think about it, our crank sensor's are at the rear of the block and by removing and installing the balancer should' t have any affect on the sensor, but removing and installing the flywheel might throw something out of balance maybe.

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Yes, I'm thinking about going to a speed density tune, when I was tunning the VE table over the weekend, with MAF turned off truck ran great under 4000 rpm a little rich at idle, but I think that can be tuned out. And I only drive the truck maybe a 1000 miles a year. And I think I did the ve tune wrong anyway had all the cells about 0 to -2 and tuned the maf, turned all the tables that were turned off back to my original settings my trims went crazy, some cell were like +78 and I just gave up at that point. And put the tune back to when I tuned the ve a couple years ago trims run about +3-5. and I spent about 10 hour's tunning on Sunday

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  • 2 months later...

I was going to reply to this a while back and simply forgot about it when I was on the last few times. If you don't know the proper answer... DO NOT REPLY... My biggest issue with post on here lately has been all of the people posting who have no actual knowledge about what it is they are actually posting about. Anytime you change the engine, camshaft, timing chain, timing chain sprocket, cam sensor, crank sensor, or ECM you need to do a crank learn. Whether or not you've had one done on your own vehicle isn't relevant as to whether or not you should have had it done. On the same point, even if you don't get a code for it you still need it done. When doing the job on HPT it won't tell you if you were successful. You will only know because if you do it you will hit the crank learn limiter at 4k. If you didn't do it correctly it will just rev. I will add that it doesn't mean to just lower the rev limiter to 4k, I once had a customer do that. :( and then told me he had to do that to get it to take. Do not do that.

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