ssheets

iTrader: (1)

I searched last night and read a page or two of old posts, but I still have a question.

I've installed a new PCM so theoretically I should do a crank relearn. It looks like I can initiate it using EFI Live, don't I need to performa a specific task though once it's enabled?

Doesn't say much in the EFI help file other than

1Hotbird

iTrader: (5)

I would also like to know. I have had several differant computers in my car and never had to do the relearn?

sreve

iTrader: (3)

no ses no worries , be happy

1Hotbird

iTrader: (5)

still would like to know how in case the need to do it comes up!!

sreve

iTrader: (3)

as stated no service eng soon code po1336 crank variation not learned
don't worry be happy!

1Hotbird

iTrader: (5)

I still want to know how

sreve

iTrader: (3)

you are hopeless

ssheets

iTrader: (1)

From what I've read, unless you do a CKP your PCM can not perform certain misfire diagnostics.

Most of us that are interested in learning don't take the no SES no worry avenue. Even it's the right answer some explanation would be warranted to support it.

shoemike

iTrader: (25)

did you flash the tune and operating system
that was installed on the old PCM?

sreve

iTrader: (3)

the crank variation relearn code can set from changing parts the check engine or service engine soon light comes on code p01336. if it comes on it requires you to run the engine at high rpm with no load to complete the test, i really do not like that high rpm with no load unless i have too. if the code does not set that's where the don't worry be happy comes in. sorry if i sounded like a ***** not my intention.
this code is some thing i have seen on a stock motor with no other obvious problems alot of times a relearn fixes them with no come back. if everything else is right it will take care of it's self. see the attached p.d.f.

ssheets

iTrader: (1)

Thanks, I appreciate the explanation.

Oh, and it's a new PCM with a new cam and heads, but everything else is the same and undisturbed. I thought I read somewhere about crank misfire not working...I'll read the pdf.

ssheets

iTrader: (1)

The pdf is great, thanks.
I still don't understand why it says always perform a CKP when replacing the PCM (among other things) yet my PCM states that "misfire monitoring = ready" and I have no trouble codes. I know Jesse programmed out the low rpm misfire codes due to the cam overlap...I'm not saying I'm worried I have a problem I'm just trying to understand the process.

vtanju

iTrader: (2)

hi,

as far as i know you can only do a crank relearn with a tech2 scan tool, but if you dont have any codes, dont worry about it.

hope this helps

sreve

iTrader: (3)

the after markets in there with relearn. the tech2 might be smarter than what i'm used to.
if it does not spit a code it does not need a relearn. if you try to teach it something it already knows this will be the result

ssheets

iTrader: (1)

Yeah, you're probably right. It looks like EFILive can do it, but I don't have a compelling reason to test it out.

LS1BirdGirl

I know I tried to do a CKP on my bird with the matco proscan but it doesnt have the capability. I wanted to do it because I have a misfire which is being very difficult to pin down and the information its giving me is pretty random. I know when I worked at the Chevy dealer and had access to a Tech 2 guys would never look at a misfire counter without doing a Crank position relearn first.

wait4me

iTrader: (10)

EFIlive does the relearns just fine. You are supposed to do a relearn anytime you replace the cam or crank sensor, or any rotating mass. It just sets up the pcm to accurately detect missfires and helps with spark octane % table usage. It only takes a few seconds to do with Efilive. It sets the test, then the ecm will make a different rev limit usally 4200rpms and then it measures the difference from accell, then shuts off fuel and checks the decell. Then it sees the actual chain slop on the timing chain.

Even in GM tis software it tells you to do the relearn. The data is stored in 4000-8000 in the bin file. It cant be over written unless the test is manually performed.

onephatZ28

iTrader: (8)

If you unplug the crank sensor and someone tried to start the car with it unplugged do you have to do a relearn. also would it cause it car not to start?

Thanks

joecar

No, not necessary.

Unplugged crank sensor will not alloow the engine to start or run because the PCM triggers off the crank sensor to fire the injectors and spark plugs.


As Wait4Me said, when rotating mass is altered (e.g. torque converter is swapped), then it's a good idea to do a crank relearn;

the PCM's misfire monitor requires accurate relearn data or it will detect "false" misfires.

EFILive gives you on-screen instructions when you go to do the crank relearn... basically, when you initiate the relearn, you have 10 seconds to smoothly increase RPM to 4000, and when you feel the limiter kick in (feels like a short series of quick misses, lasting about a quarter of a second), you completely release the throttle; the whole procedure happpens so quick.

I also tried this with a Genisys scantool, and it would not work.

The EFILive scantool just this just fine, no problem.

sreve

iTrader: (3)

a Genisys scantool is the smartest one i use and yes you are right its not going to happen unless p0136 is set. the Genisys is a POS though it does pretty good on GM lord help you if you plug it in a ford or a dodge.
the streched timing chain is a good explanation of a relearn fixing a p0136 with no come backs.



quote:relearn... when you initiate the relearn, you have 10 seconds to smoothly increase RPM to 4000, and when you feel the limiter kick in (feels like a short series of quick misses, lasting about a quarter of a second), you completely release the throttle; the whole procedure happpens so quick.

that's what the instructions say, but with an OTC you just put your foot to the floor and the test will complete. if you do it the right way mr. OTC won't complete the test, its why i will not do one unless i have too.