Crankshaft Relearn Procedure

[kx250ryder]

I got a CPS by mail from saturnparts.net along with the gaskets for the valve cover (DOHC).

I was going to do this all today, but then noticed that most say you need a Tech2 scanner to achieve the crankshaft relearn procedure.

I did find this post which suggests otherwise:
http://www.saturnfans.com/forums/sho...59&postcount=6

Does this procedure apply to the 1998 SL2 I am working on? I noticed both of the poster's cars were pre-OBDII. I would really like to avoid a dealership at all costs if possible.

It will be a couple weeks before I can try this because the car has a SES code P0420 for the converter that I still need to replace.

[rc1488]

i do not believe you need anything other than a 10mm socket. You can replace the sensor and either let the car relearn over a period of driving cycles or force a relean my disconnecting the batter/remove PCM B fuse.

[Dr B]

It is my understanding that the relearn thing is specific to 96 models(well problems) with learning .
It has been suggested ,there was a glitch in the programming(first year)obd 2

[ssicarman]

Ideally the crank relearn should be done when the crank sensor is replaced.
It needs to be done when the crankshaft or the engine is replaced. This is so that the PCM knows for sure where the tooth on the crank that locates the #4 cylinder top dead center is.

[kx250ryder]

I agree that the relearn probably needs to take place. My question is of the now three methods of re-learn (from costliest in time and dollars to least):

1. Saturn dealer uses Tech2 to relearn
2. I perform the specific drive cycle mentioned by Low Saturn
3. I install the sensor and just drive it per rc1488

Will option 3 work? Or must I use option 2 or worse the dreaded "no-grease-in-the-rear-pay-dealer-labor-cost" option 1?

[Old95SL2]

Originally Posted by kx250ryder

Will option 3 work? Or must I use option 2 or worse the dreaded "no-grease-in-the-rear-pay-dealer-labor-cost" option 1?

Just change it and drive, worked fine on my 99.

[TwinRevver]

Originally Posted by ssicarman

Ideally the crank relearn should be done when the crank sensor is replaced.
It needs to be done when the crankshaft or the engine is replaced. This is so that the PCM knows for sure where the tooth on the crank that locates the #4 cylinder top dead center is.

I swapped an 98 motor with about 60k miles in 95 SL2 and swapped all necessary sensors over. So i need to do crank relearn??? How does low saturn do it?? (option #2).....

[ssicarman]

I have yet to see a problem caused by not doing a crank relearn after replacing the CPS. There is something to be said for modern production line tolerances. That would include engines and crankshafts. Now if you have an unexplained miss or similar then a relearn may be the fix if the sensor, crank or engine have been replaced.

So far as I am aware the ONLY way to do a relearn is with the Tech 2 scan tool.

[rc1488]

when in put the '97 engine in the '99 car it worked fine with no relearn

[TwinRevver]

would this cause 20 mpg?? yes the ects and conn. is fine(brass)...

[BarnOwl]

In my experience, and I had a '96 that had to get a crankshaft relearn, if you aren't having another problem, you don't need a crankshaft relearn. In my case, I was getting a P0300 code that I couldn't get to go away. I spent a lot of time and money chasing that code. OTOH, I swapped an engine from a '97 SC2 into a '97 SW2 and didn't need to get the relearn done. It's running great!!!

[ssicarman]

Originally Posted by TwinRevver

would this cause 20 mpg?? yes the ects and conn. is fine(brass)...

I would tend to think that it will not. Have you replaced the thermostat?

[kx250ryder]

Change and drive seems to have worked so far. But I have heard that a re-learn wouldn't happen with a SES light set. So until I swap out the cat for the P0420 code and clear it out, I don't know if things will stay ok or not.