I feel dumb

[Haulinbass02]

So I posted a while back about a misfire and rich condition on my #1 cylinder and I've been chasing my tail trying to fix it until today. After new parts, pulling the valve cover and checking the rockers, pushrods etc, I finally did the CASE relearn. I NEVER had a code for it, but given ALL that I did to the motor I figured why not.

Now, mind you, when I had the coil packs mis-wired I DID a CASE relearn. But after fixing that wire harness issue, I never did the relearn again. All that to say, once I did the CASE relearn today, all my woes went away. Truck runs smooth as a cammed LQ4/9 can. No misfire, no pop, no hesitation. Very strong for a partially tuned truck.

So, ANYONE who might be having those kind of issues, especially after new cam or parts of that nature, I implore you to do a CASE relearn first. I have a funny feeling all my issues would have been fixed without replacing most of the parts I did.

On to the good stuff, I am having a warm ECT start issue. If the truck is cold, starts just fine. Warm, not so much. I have to open the throttle with my foot to get it to start. I'm attaching my latest tune. I did add fuel to the initial tune but I'm thinking maybe it needs more timing? There doesn't seem to be enough given how much it likes when it is running. Any pointers?

Thanks!

99 Silverado VE Tune Cal 1.2.20.hpt

[kingtal0n]

What the hell is a case relearn


hahaha

[kevin87turbot]

Go to the Idle tab and increase the Startup Airflow Initial...primarily in the warmer coolant area of the table. I see you've added some, but need to add some more. You can also add some in the Friction Airflow Initial table.
Another thing that some people overlook...make sure that your IAC is in the 40-60 range once the engine is up to temp.

[5FDP]

What the hell is a case relearn


hahaha

Used to sync the cam and crank. Not sure if you're really joking though.

[Haulinbass02]

Awesome, I?m doing this now and will check the IAC .

[kingtal0n]

All I have is "crank" relearn. Why doesn't the 411 have a case relearn, and while we are on the subject it never seemed to require it even after a cam swap (crank or case relearn)

[blindsquirrel]

Crank Angle Sensor Error (CASE) relearn, Crankshaft Position Sensor Variation, crank relearn, it is different names for the same damn thing. Some is pure made-up slang and some is different language GM used over the years.

[Haulinbass02]

Some never seems to need the relearn and others obviously do. I had a 4.8 years ago that I did a cam swap in and it ran fine without doing one. Buddy did. same cam in his 4.8 and needed it. In my opinion it doesn?t hurt to do one anytime you change something that relies on the timing like that.

[TheMechanic]

GM calls it a Crankshaft Position System Variation Learn or CKP relearn

[2xLS1]

It has nothing to do with the cam sensor. It is the ECM/PCM storage of the crank reluctor characteristic while accelerating. That is why it is performed while accelerating to 4K rpm from idle. It should only need to be done if the crank sensor, crank reluctor, or ECM/PCM are different from each other since the last time it was characterized. And it is only needed for accurate misfire detection. There is no syncing of the crank and cam sensors when it is done. One other thing that can cause the characterization to be lost is if the ignition power is left on while battery power is lost or runs down on the ECM/PCM.

[TheMechanic]

I always perform one after updated software as it is usually required per SPS after update and clear codes due to several times many years prior I did not do it and would get a P0315.

[2xLS1]

Its P1331 in P01 PCMs. And just clearing codes will not erase the characterization.

[TheMechanic]

Its P1331 in P01 PCMs. And just clearing codes will not erase the characterization.

That's why I do what I do.

[mxhalofan]

So I posted a while back about a misfire and rich condition on my #1 cylinder and I've been chasing my tail trying to fix it until today. After new parts, pulling the valve cover and checking the rockers, pushrods etc, I finally did the CASE relearn. I NEVER had a code for it, but given ALL that I did to the motor I figured why not.

Now, mind you, when I had the coil packs mis-wired I DID a CASE relearn. But after fixing that wire harness issue, I never did the relearn again. All that to say, once I did the CASE relearn today, all my woes went away. Truck runs smooth as a cammed LQ4/9 can. No misfire, no pop, no hesitation. Very strong for a partially tuned truck.

So, ANYONE who might be having those kind of issues, especially after new cam or parts of that nature, I implore you to do a CASE relearn first. I have a funny feeling all my issues would have been fixed without replacing most of the parts I did.

On to the good stuff, I am having a warm ECT start issue. If the truck is cold, starts just fine. Warm, not so much. I have to open the throttle with my foot to get it to start. I'm attaching my latest tune. I did add fuel to the initial tune but I'm thinking maybe it needs more timing? There doesn't seem to be enough given how much it likes when it is running. Any pointers?

Thanks!

99 Silverado VE Tune Cal 1.2.20.hpt

Hey what cam did you install? Thanks

[2xLS1]

That's why I do what I do.

Just realize that what you might do at a dealership might not apply to modified vehicles and non stock calibrations.

[kingtal0n]

In my file I adjusted the rev limiter in neutral to 2800rpm. It's amazing.

But the crank sensor relearn thing suggests the engine be revved to 4000rpm or whatever OEM redline...

Does it matter if mine only goes to 2800rpm?

I tried it recently just to see what would happen and there is no confirmation that it worked or did anything at all... Disappointed but still happy the car runs
always a plus when it starts like a normal car and selects the right gears, etc... how much to ask!

[TheMechanic]

The process involves flooring the pedal at an idle until fuel cutoff. Then release pedal and it will idle down, learning position at the same time. It is possible although I don't know for sure but the software might disable the rev limiter to perform the CKP relearn.

[Haulinbass02]

TSP Stage 3 low lift, 216/220 .550/.550 112 LSA

[blindsquirrel]

It won't work with the rev limit lower than stock. The relearn function isn't configured to live in a world where us end users change things.

[2xLS1]

And there has never been confirmation that it completed successfully with HP Tuners but I've found that if it enables the button to start the procedure that it usually completes it successfully.