'97 Chevy 454 w/ 0411 timing will not go above 27deg. Assist with CASE Relearn?

I am needing an extra pair of eyes to figure out why I am not getting any spark advance past 27deg. I've only recently noticed this change, and it looks like it may have started after I changed my distributor cap and rotor due to severe oxidation of the terminals and crossfiring.

I'm posting the tune/log/channels for the curious. I would hope though, so please do not ask why in this thread, that my AFRs going to the opposite of rich. It's supposed to. If you have questions about that, PM me.

P1336 and P1345 have been disabled since I replaced the cap, since it became active after swapping it and the rotor.

If this is a CASE relearn issue, I have tried multiple time to perform this. To the point of "E-brake engaged, Start engine, click relearn, rev engine, release throttle quickly to let engine get back to idle, then shut down." All within about 5sec after engine start. I've never been able to get it to work.

If anyone has any advice, please assist.

I can't check the tune or anything else. I'm on the phone but your should be logging cam offset or cam retard and it should be within the range of 10* + - of 0.

On these setups if your within 5* and can't get a case relearn. There shouldn't be any issues or 1345 code. I've noticed on my setup. With my cam offset around 2* there is a fractional difference in commanded and actual. Around a half a degree difference at most.

Well, some progress. I was not able to do a crank relearn, BUT, with the offset being -50 I was able to turn the dizzy to get it to -3.

I'm now able to get more than 27? out of it. Still bucking a little, but not as bad.

Slight update. I had to replace the distributor, again, after trying to coat the insides with dielectric grease to prevent corrosion. The cap was full of corrosion on the terminals again, and there were literally beads of aluminum corrosion bouncing around inside. Put it back together and it ran like crap.

Bought a new dizzy from Auto zone (one of their gold models) and it fired right up. Got dizzy close to zero but had cam offset code. Took it to mechanic that did relearn with scanner before and it wouldn't teach. Through trial and error we found that if you reduce the rev limiter to any less than factory (which is 5600rpm while in p/n) it will NEVER relearn.

So, that's probably been that whole problem before. I'm not going to.move the dizzy and retest. I'll simply wait until it fouls again then try.

I did however experiment and put the dizzy at -50? to expose the cap mounting screws, hoping that I could leave it in that position to make cap swaps easier. The ECU would not accept this and kept throwing the cam offset code. So, there's that.

When your cam sink is off, it causes rotor phasing to be off. It needs to be as close to zero for a reason. Anything more than 5 or so degrees from zero, and it start to cause phase issues, this in turn starts destroying the inside of the cap and rotor. Also this limits timing, as the ecm knows once the rotor is a certain distance from the lug in the rotor you will either get a misfire, or it will jump to the nearest lug.

Quote:

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Originally Posted by mbray01

When your cam sink is off, it causes rotor phasing to be off. It needs to be as close to zero for a reason. Anything more than 5 or so degrees from zero, and it start to cause phase issues, this in turn starts destroying the inside of the cap and rotor. Also this limits timing, as the ecm knows once the rotor is a certain distance from the lug in the rotor you will either get a misfire, or it will jump to the nearest lug.

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So, theoretically could I have jumped the rotor a tooth so the cam offset would be near zero when the dizzy was in a serviceable position? Then everything would've been fine?

Im thinking that if it isnt serviceable where it needs to be (sync wise) then its likely off a tooth anyway. Ive never had service issues with one when properly sync'd

Quick update on this. The reason why I could not CASE relearn was due to the RPM limits I had for VSS failure and P/N.

They MUST be at least:
VSS Fail- 5,600rpm Resume- 5,550
PN- 5,600 resume- 5,550

Less than that it'll bump off the rev limiter forever and never relearn. This was tested using a MAC tools scanner AND hptuners.

I'd like to know why this is... but at least I can do it now.

I swapped the whole dizzy again with a lifetime warranty Duralast unit. At least it's metal, and it's painted. No corrosion or issues noted yet since around January/February.

Why do you care about CASE learn anyway?

So if I have any misfires, I can actually detect them.

Reviving an old thread... because it's my thread and I finally found the answer:

You must ground pins 32 and 34 on the 0411 C1 connector to tell the ECU that the truck is in park/neutral (even though the PCM knows it, it wants that ground!).

After that, then you can do a crank relearn... and this is from the master himself.