I was told that only a GM dealer or someone with tuning software can perform a crank relearn. I saw this same info over and over when I researched awhile back. I had a new, tuned computer done for my truck and it needs to have this procedure done. I just found the link below and it says that I can just do it myself. Who is right? Thanks for your help.

https://ls1tech.com/forums/pcm-diagn...procedure.html

 

Are you getting a P1336 code? If not, you don't need to perform the crank variation relearn. If your getting the P1336 code, then you need a Tech II or Hp Tuners to perform the relearn.

Russ Kemp

 

1336 just means it has not been performed ever. But for proper misfire detection any time a pcm or internal mods are performed or sensors are changed it is advised to perform crank relearn. It allows the computer to adjust itself to the new critieria for proper detection of misfire and timing events. It's fractional but it has no effect on how the vehicle performs and it will not take it from not running to running state if there is a problem causing the vehicle not to run. There seems to be a cloud of misinformation surrounding it's purpose and what it's for and this is the dope from gm manuals.

Most any snap on matco HP tuners etc scanners can perform a crank relearn in the functional test or setup menu.

 

I forget what the actual code is, its been a decent amount of time since I looked. But I believe it was a mis-fire code. And my check engine light flashes - like warning warning - everyday for well over a year. The truck runs 100% fine.

And the computer is not the original one BTW. I purchased the tune and computer together so I would not have downtime.

There is a local tuner who said he can do it, but wants $100 to do so. Seems ridiculous to me, ESPECIALLY if I can do it on my own.

 

The procedure to do it with a drive cycle is in the link you posted although I've never heard of doing it that way. Have you even tried it? But with a flashing SES light I would bet you have a real misfire. You need a scanner to look at real time misfires and misfire history by cylinder.

 

When I swapped to my lq4, I had the flashing misfire code until I did the relearn. I have efi live and it takes all of 5 minutes to do... $100 seems pretty damn steep for very little work. Not sure I would trust the other procedure.

 

Anybody in the Westchester County, NY area want to help a fellow member out?

I'm 99% sure I dont have aa misfire, much like Rob above. The light flashes then goes off then comes back etc etc. I have Torque on my phone and have logged the misfires. Some of the cylinders had tens of thousands over a few months. Others like 4. Truck runs great.

I haven't tried the procedure in the link. That was the point of my post.... that everyone was telling me it had to be done through a computer but then I found this. And it does sound a bit scary.

 

"Can" and "will" are two different things. I have done the
crank relearn with a very old version of EFILive scan tool
(from back before they did tuning) and I've done it with
some version of HPTuners or other. But in between I and
others have also had difficulty in getting the routine to
go. There are some faults that can inhibit crank learn from
running (dealership even had to fix one mystery fault on
mine, some EVAP system deal that did not show on the
third party tools and only the Tech-II).

The conditions for running it in the scan tools seem to be
a bit finicky and you shouldn't give up right away, but pay
particular attention to the engine operating point / pedal
position requirements and be patient.