LS6427

iTrader: (2)

I'll have to swing by the dealer, they don't charge for little fast stuff like this. Maybe they can get it to go out by doing the crank relearn process.

.

madmax4499

iTrader: (3)

ok, how do you or where do i look to run the test with efi live. i dont see it anywhere in the scan tool.


FOUND IT,

corpserodeo666

iTrader: (12)

I'll keep this alive. Do I need to do a case relearn since I replaced my PCM? The car will not REV past 4000 RPM in park or neutral.

The car also sounds like it has a misfire. Could it be because of this? It never used to do that with the old PCM.

It does not take my VE changes after I flash them in the PCM.

Please help me out with this, since I have hit a brick wall.

Petersen

Using the Tech II go in to diagnostics and then go to module setup and then it tells you step by step how to do it make sure you have a rev limiter on.. This might work not sure if its cammed thought

corpserodeo666

iTrader: (12)

The car is heavily modified. Who has one of these Tech II's I have a Modis from Snap On. Will that work?

jay_lt4

iTrader: (4)

case relearn has nothing to do with how the engine runs, it is only for misfire monitor diagnostics

edcmat-l1

iTrader: (10)

You can say it til you're blue in the face, for whatever reason, people don't seem to get it.

Once again guys and gals, IT'S FOR MISFIRE PURPOSES ONLY! Once you modify an engine, specifically an aftermarket cam, you disturb what was a SMOOTH ROTATION of the crankshaft. The case relearn is there so the computer can "learn" the small idiosyncrasies in crank to cam timing. It uses this information to better detect small misfires. There is no credible evidence it's used for anything more.

Not only that, but through tuning, you dumb down the misfire detection by altering the misfire tables. This is a must, otherwise the computer will repeatedly throw misfire codes as it's detecting the uneven rotation of the crank, caused by the lopey cam.

Additionally, turning off the code in the computer does nothing but keep it from setting the P1336. With the code turned off, it can still detect misfires. The ONLY TIME IT CANNOT DETECT MISFIRES IS WHEN THE CODE IS SET!

As a side note, the ONLY scan tool I've had repeated success using to run the case relearn, is a TECH2. All of the aftermarket scanners seem to have some problems. Not saying they won't or can't do it, but I've had mixed results with most all of them. Keep in mind I own 5 different scanners, besides my HPT or EFIlive.

corpserodeo666

iTrader: (12)

So I need to know. Do I need to do anything with this? I am throwing the p1336 code. Should I have my tuner get risk of it. Or should I do something else? I can post my .hpt file if need. Thanks.

joecar

Looks like you have at least 2 issues:
- P/N rev limiter is set to 4000,
- you have a misfire problem (due to: ignition, lean/rich, air leak, compression leak, other);

How do you know the PCM doesn't flash...? When you read it back does it compare the same...? If MAF is being used, then VE table is used only during throttle/airflow transients, so you won't see the changes unless you disable the MAF and LTFT/STFT trimming.

Or you may have a PCM with a problem.

corpserodeo666

iTrader: (12)

This is an SD car. So there is no MAF. If it is the PCM this would be my 2nd one. I will be able to do a few test to the car in the next day or two to see what really might be going on. If anything changes I will post here.

The rev limiter is set only if its in neutral or park. But isn't that how it just is from the factory? The trans is a 4l80e with FMVB. The PCM flashes but all the changes I make to the VE tables stay the same. I will double check or I can post my .hpt file so you guys can look over it.

LS6427

iTrader: (2)

You guys wanna hear some funny ****.................I've had some weird missing/stumbling issues in the past week or so....my Crank Relearn code has been on for more than a year because my relearn would not PASS no matter how many times we tried it. So I said screw it and left it on, it had no effect on how my engine performed.

Since these weird missing/stumbling issues have started....that code is gone and does not show up anymore.

WTF!!!!!! These PCM's are just wacky, silly little bastards.

.

joecar

Does the PCM throw a MAF DTC...?

corpserodeo666

iTrader: (12)

Nope I do not think so.

joecar

Then it is not running in SD mode...

it is not running exclusively from the VE table...

and since you have no MAF, it is using a MAF value "computed" from MAP and RPM.

kristov

Does this still hold true?

That the CASE relearn does not affect how the engine runs and is purely for diagnostics?

mrvedit

EDIT: A more experienced tuner disagrees - see below.

I'm not an expert, but my personal single experience is different from edcmat-l1.
After I replaced the stock balancer on my LS2 with an ATI, I got camshaft sensor code (IIRC P0341) which would quickly come back after clearing it.
Thinking I must have damaged it during the balancer change, I bought and installed a new one, but still got codes. I then performed the crank relearn and the code never came back.

2xLS1

iTrader: (25)

CASE Learn has absolutely nothing to do with a cam sensor.

mrvedit

I defer to your greater experience and updated my post.

While it "once" solved my cam sensor code, I understand the mysteries of computers and engines may have made that a coincidence.

mrvedit

Also then, what symptoms indicate that a CASE Relearn is needed?

I found this informative thread on when various types of GM "Relearns" are needed and how to perform them:
http://www.fullsizechevy.com/forum/g...t-relearn.html

2xLS1

iTrader: (25)

Anytime a crank position sensor or pcm has been changed a CASE learn should be performed. CASE learn matches the characteristics of the crank position Sensor to the pcm. The only other time I'm aware of when a pcm can lose it's stored data is if the key is left on while B+ power is disconnected from the pcm. For instance if you leave the key in the on position and the battery runs down or is disconnected. I have had it correct cylinders showing misfires falsely after an engine has been replaced. That is the only time I've seen it correct anything. And what edcmat-l1 said is 100% correct. Listen closely when he posts. He is probably one of the top 5 tuners in the country.