Maybe I should rephrase that.
How does the VCM know when cam driven valves are opening and closing relative to piston travel?

My theory and supposition is.. it doesnt! If it does, please explain how. Only possible way I can think of is the MAP... and that's a reach because of plenum capacity.

Again.. I am not saying that's the problem, but if I accept that the engine has no power to increase speed from cruise, then it must always be considered the same now as it was in the past, before electronic systems.

 

When they say, "CKP correlation procedure", (incorrect terminology) I can only assume that they did the crankshaft position sensor relearn, which is NOT camshaft retard. Were you there when they did it? Did you see what they did? Can you describe it for me? This goes back to the comment I made earlier about "weak diagnostic skills", I sure hope this wasn't at a GM dealer


Diagnostic trouble code P1345 indicates that cam/crank correlation is incorrect. Checking "cam/crank alignment" could mean all they checked for was the presence of P1345 in memory. If P1345 is not in memory, cam crank correlation is within ~25 degrees, in other words, it's "in the ball park". But that's a pretty big ball park. After snapping the throttle to 2,000 RPM and returning to idle, what is the actual reading of camshaft retard? The scan tool will display camshaft retard in positive or negative degrees, (it will be less than ~25).

When these things are running right, they can easily pull a 3500# trailer, so I doubt your modifications are causing the lack of power. If the PCM hasn't been flashed for the larger tires/wheels, it will affect shift points and how smooth or hash it shifts. It will also affect your speedometer and fuel mileage, but not the lack of power.

By any chance do you have an oil type air filter ie, K&N?

 

OK...

PCM not reflashed
Have K&N high volume dry air filter

Called dealer, they had no idea what I was talking about, called another local shop. They have the Snap on computer, and looked through the menu.....nothing for camshaft retard.

They went to Alldata and pulled instructions for distributor replacement. Looks like the procedure covers the cam/crank/valve/piston correlation. He said he could do the the distributor alignment in an hour.

Is this correct? , or advised?

If this is wrong, could you give me the exact terminology. Nobody seems to know what camshaft retard is.


btw....how/why could the camshaft get retarded?

 

Wallace.. see if you can find a drawing of a Timing chain setup.
First, if a timing chain is loose and jumps a tooth, the cam will be retarded in comparison to piston travel. That isnt real likely unless the timing chain is pretty loose... but shouldnt be ruled out.

But there's other ways, too and they relate to the mfg process and a bad part slipping through.. thus causing what the numskull mechanic's reference to a 'dog engine'.

The slot in the crank snout might be cut wrong. The slot in the primary sprocket wrong in relation to teeth and index {wouldnt think so} The holes and index pin in cam, wrong.

Or the thing just set up one tooth off, in the first place.
Remember.. the dist is set up to the position of the CK position sensor and piston TDC, and doesnt care what tooth in the cam it sets in.

all conjecture

 

Wallace, are there any shops around there that know what they're doing and how to use their equipment? Wow, I'm beginning to think they're all numbskulls. Camshaft retard is the synchronization of the crankshaft position sensor with the crankshaft, and the camshaft position sensor with the camshaft. The P1345 will set if the falling edge of the cam sensor signal leads or lags the falling edge of the crank sensor by more than 26 degrees. Camshaft retard has a substantial affect on ignition timing and can greatly reduce the longevity of the distributor cap and rotor if it's not within specs. When both sensors are synchronized, the PCM also uses the data for identifying which cylinder/cylinders are misfiring. Keep looking for a tech and a shop that understand it.

 

OK, I'll look for a better shop next week, and report back.

I live in Boulder, CO...they hate cars here. Although they have the coolest Ferrari garage and race set-up shop here you could imagine. Surgical gloves, tiny instruments and magnifying lights. Maybe I'll ask them for a referral.

Thanks