Changed out the CKP sensor trying to solve a power/fuel economy problem that has led down many rabbit holes. I decided to spare no expense and get myself a proper bidirectional scan tool so I can do these procedures. Local shop(s) have a 3 week waiting list to see clients so I'm just doing everything myself.

I did the CKP relearn yesterday and it turned out fine. I followed the instructions on my Autel and by the end of it the screen said CKP variation learned. I don't think I did it right because when I went to test drive it felt way slower than before. I don't think I was giving it enough WOT.

WOT literally means punch it to the floor, right? Well today when I tried it again again, I followed the instructions, then I punched it to the floor, triggered the fuel cut off, but the system didn't say CKP variation was learned. It was still prompting for WOT. I did it 3 more times and still didn't switch status. I'm worried if I keep doing this I'm going to blow something up. So I stopped and went looking for answers.

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Does the fact that I may have a suspected exhaust restriction jave anything to do with it? I have enough evidence that points to a restricted catalyst, but I don't trust my own diagnostics enough to confirm it. I don't know all the sensor data involved in this calibration so I'm assuming MAF might be one of them.

 

 

I found this that kind of addresses my concern
https://productforum.autorepairdata....ead.php?t=1512

 

I took it out to test drive again. Maybe the poor acceleration was just all in my head yesterday. But I got some pretty ****ty performance driving ot on that incomplete CKP variation relearn from earlier. Would not accelerate past 35 MPH at all! When it did reach 35 MPH, RPM would come down a bit and would not rev any higher!

So I dragged it back onto my garage, did a CKP relearn again, and it just could not complete. RPM would not go past 3500 to reach fuel cutoff to complete the test.

I recorded a video of it.
I have no clue what to do next.

https://drive.google.com/file/d/1NL9...w?usp=drivesdk

 

I said before that crank sensor relearn won't cause a misfire. It only uses the learned info for misfire detection. As I said before, you do crank sensor relearns last, after all is running great! After all, why would you record a sh***y waveform when the engine isn't running good to use for misfire detection? Looks like you don't believe me.

This crank sensor relearn isn't going to fix any performance problems, but since you want to try it........

PCM is probably seeing a pending or hard misfire (with the really screwed up waveform that you learned) and is refusing to do the crank sensor relearn. I'm quite sure you will have to clear the codes in same key cycle before you start the crank sensor relearn. Pay attention to the hold the brake pedal with your foot and set emergency brake (at least enough to light the light). Sequence of this procedure is everything. I take it you have the factory procedure available? If you can't get it above 3500 to the fuel cutoff, you will need to fix that problem in order to do a crank sensor relearn.

If you want my help further, we need to get back to the other thread. I'm betting you have restricted exhaust choking your engine and causing the low MAF sensor readings at RPM, but you stopped short of diagnosing it. Did you even read through the running compression test info I linked to? That's a definitive test.
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It's not that I don't believe you. I just figured while putting this breathing issue and whether or not the catalyst is restricted on the back burner until I arrive at a breakthrough on what to test/replace next, I could start looking into the CKP relearn procedure for more accurate misfire data. I didn't mean to stop short of diagnosing that. I just figured that having correct misfire data would help in troubleshooting the breathing issue.

But, my first hand experience was this. I did the relearn, test drove for any discrepancies, and what I felt afterwards was a smoother idle. I'm not kidding. Misfire detection still seeing misfires, but not nearly as many as before. However going down the road, it just did not want to accelerate; worst than before. So I was thinking "maybe I accelerated it to WOT too slow during the test and it recorded that TPS data". So I kept trying it until I got to this point where it seems stuck in "limp mode" and can't finish another procedure.

Oh, "do crank sensor relearns last". Sorry Les, I think I really missed that part. I understand now that I have bad data recorded. I've been searching for a way to just clear the CKP data (not relearn it), like when I'm having to flash a firmware changes to Android and Raspberry Pi devices at work to a default state.

Yes, I did read the procedure on a compresison test. I mixed up my priorities here and pushed that further to last. I almost forgot about it.

Whelp, I have an answer to my initial question. I screwed up on this one. I'm just going to push this thread to the side for now. At least it can still move around, just not driven past 35 MPH.

 

When I did mine, fuel cutoff occurred way before redline, at something like 4000RPM. The first couple of times I tried, it didn't learn. Then I realized I wasn't following one of the steps (holding the brake pedal, IIRC). When I followed the procedure EXACTLY, it worked the first time.

I'm not sure how relevant that is to your situation, but you never know...