The easy fix would have been pushing it off a cliff.

Seriously, I considered that possibility at the outset. The first problem was the vehicle ran so poorly before the shim that it was not safe to drive. The second thing is the diagnostic flow chart says relearn won't initiate with a DTC present. Since the P0335 was solid before the shim it was a crap shoot as to whether it would be a waste of money to try it. The third thing is I don't have the SW to initiate the relearn and I'm not inclined to buy it. So, was any of it simple? No. Would a relearn have executed? I don't know. The documentation seemed to say not.

And finally, for those who will say I should have taken it to a dealer... Despite the fact that all my vehicles are Chevrolet I have zero confidence in their dealer mechanics. I have had more bad experiences with them than good ones. Getting them to actually correct issues, even obvious ones, usually takes multiple visits and even then they usually find a way to screw something else up. My latest experience was classic where I took my Vette in for an oil change and it came back 2 quarts low with greasy hand prints all over the hood and windshield. The service could care less about the incident and I had to coerce them into fixing it. The only way I'll ever have my vehicles serviced by Chevy again is for warranty issues and then I'm gritting my teeth the whole time it's there. And not to beat on just the dealers...it's hard to find any shop these days with competent mechanics or who don't want to take you for every nickel they can. Good and honest mechanics are tough to find these days, which is why resources like this forum have become so invaluable.

 

Finding a good dealership can be a challenge, finding a good technician is a bigger one. You are correct about the relearn; The engine must run and there can't be any crank sensor DTC's present. Now that you have it running with no DTC's, it might be worthwhile to take it to an independant shop and ask if they are familiar with the relearn procedure. If so, have them do it... takes less than a half hour labor. The ECM is using data from the original orientation of the crank sensor, which is obviously close; but the odds of being struck by lightning after winning the lottery, two days in a row, are probably far better than the odds of having the sensor data correct the way it is. Having them check and adjust camshaft retard wouldn't be a bad idea either, as long as they're in there.

 

Definitely scheduling a relearn!

 

You may or may not notice a difference in driveability after they do it, so don't get your hopes up too high Cam retard can be off by 20 or so degrees without setting a DTC. If it is, you'll notice a difference in fuel mileage after they correct it. If it gets up around 24 degrees, it will set P1345. Let us know what happens.