Installed Nelson Tune...

conboy · April 5, 2008

Truck cranked on first try, didn't die, ran just like normal. No lights on whatsoever just a DIC reading to change my oil. Do I still need a crank relearn? Or did I do something wrong?

alaska511 · April 5, 2008

if yeou have no SES light, you're good to go

VMax2007 · April 5, 2008

if yeou have no SES light, you're good to go

You sure about that Scott? I have heard conflicting stories about that. Many say that you should get a Crank Relearn regardless of whether or not you get an SES light. I have also heard that you won't get the full benefit of the tune without it. I am not saying this is all true, it's just what I have read in my mnay hours of research.

I say get a Crank Relearn just to be sure, it can't hurt and it's so simple to do.

svensk · April 5, 2008

I agree, get the relearn.

omegafiler · April 5, 2008

Yeah, it's always been recommended for all current and recent GM vehicles I've owned whenever you replace the PCM. It specifically says to do this in the GM service manuals. I didn't have to do this with the SCT handheld on the YD since the PCM isn't replaced, but I always had it done with other vehicles I swapped out the PCM for a custom tune - whether light turns on or not.

It's very easy to have this done, so why not? Well, here is some info that I got from another forum awhile ago.

When you perform a CASE (Crank Angle Sensor Error) learn the PCM records the *exact* relationship between the crank teeth and the crank angle sensor - for the current crank/sensor configuration.

It uses that information to detect the small acceleration of the crankshaft at the instant of each firing event. If a firing event does not occur the PCM will not detect the small crank acceleration and will log a misfire.

Note: large cams, rough roads and rough idle can cause false misfire detection.

When the PCM "learns" the crank position sensor error, it writes the learned information to non-volatile memory.

In a new PCM, that memory is blank and it will throw a code immediately indicating that a crank relearn is required.

If you swap your PCM for a PCM that is not new, i.e. one that has already had a relearn done - probably for a different engine, then the PCM does not "know" that the learned information is incorrect for the current engine. Hence it will not log a code to indicate that a relearn is needed.

If you change any part of your engine that effects the relative positioning of the crank to the crank sensor then the learned information will probably no longer be correct. And still the PCM will not know that a relearn is needed.

If the learned information is not correct, the PCM may not be able to detect valid misfires and/or may detect false misfires. P0300 codes

alaska511 · April 5, 2008

if yeou have no SES light, you're good to go

You sure about that Scott? I have heard conflicting stories about that. Many say that you should get a Crank Relearn regardless of whether or not you get an SES light. I have also heard that you won't get the full benefit of the tune without it. I am not saying this is all true, it's just what I have read in my mnay hours of research.

I say get a Crank Relearn just to be sure, it can't hurt and it's so simple to do.

just going off what I was told with mine. Melissa at Nelson said "is the light on? If not, you're okay and don't need it"

I agree, it is a quick process to have performed.

j.roffel · April 5, 2008

I never did the relearn with my w4m and now 6 or 7 months later I'm having loads of trouble with the ecu, display dosnt show the right gear I'm in, tow haul dosnt work, sometimes dosnt shift right.... Coincidence? Maybe, easier than sending your tune back to get redone? Yes.

j.roffel · April 5, 2008

if yeou have no SES light, you're good to go

You sure about that Scott? I have heard conflicting stories about that. Many say that you should get a Crank Relearn regardless of whether or not you get an SES light. I have also heard that you won't get the full benefit of the tune without it. I am not saying this is all true, it's just what I have read in my mnay hours of research.

I say get a Crank Relearn just to be sure, it can't hurt and it's so simple to do.

just going off what I was told with mine. Melissa at Nelson said "is the light on? If not, you're okay and don't need it"

I agree, it is a quick process to have performed.

So that was included in the Alaska Package eh?

VMax2007 · April 5, 2008

if yeou have no SES light, you're good to go

You sure about that Scott? I have heard conflicting stories about that. Many say that you should get a Crank Relearn regardless of whether or not you get an SES light. I have also heard that you won't get the full benefit of the tune without it. I am not saying this is all true, it's just what I have read in my mnay hours of research.

I say get a Crank Relearn just to be sure, it can't hurt and it's so simple to do.

just going off what I was told with mine. Melissa at Nelson said "is the light on? If not, you're okay and don't need it"

I agree, it is a quick process to have performed.

So that was included in the Alaska Package eh?

alaska511 · April 5, 2008

if yeou have no SES light, you're good to go

You sure about that Scott? I have heard conflicting stories about that. Many say that you should get a Crank Relearn regardless of whether or not you get an SES light. I have also heard that you won't get the full benefit of the tune without it. I am not saying this is all true, it's just what I have read in my mnay hours of research.

I say get a Crank Relearn just to be sure, it can't hurt and it's so simple to do.

just going off what I was told with mine. Melissa at Nelson said "is the light on? If not, you're okay and don't need it"

I agree, it is a quick process to have performed.

So that was included in the Alaska Package eh?

busted

cbxeric · April 5, 2008

My truck didn't turn a wheel until the relearn was done, for my peace of mind. I had a snap on scanner at my disposal so it was very easy.

Bostonsfavson · April 5, 2008

It's been my understanding that you don't need to get a crank relearn done if you don't have an SES light, as the PCM will eventually "learn" and adapt to the current configuration. Now, is this information correct? I don't know. But that's the way that I've heard it explained, and it sounds right to me. The fact that Nelson, Butch and other respected tuners say you don't need the relearn if there's no SES light seems to support it.

dubai911 · April 5, 2008

so what you need to do for a crank re-learn

omegafiler · April 5, 2008

Regarding my previous post, that was post made a few years ago by the folks at EFILive. That may be different for the latest models, but the fact that GM still suggests doing it is enough for me. Jesse also recommends a case learn/crank relearn when swapping out the PCM.