Suffering the same code, and with nearly the same number of steps taken trying to eliminate it. And with the same great operation. I hear the code can be programmed out. All I have left is replacing the baked hard wiring. I have no solution of course, but certainly in for anyone replying with progress. The only tri-9 FSM I have is a '95, so will have to round up something in a '96 if it has a diagnostic.

 

the replacement of the opti then this 336 code .. well this is what happened to me which did piss me off because I did not have the scan tool connected when I did the test run of the engine prior to installing the water pump/coolant etc... so having the 1996 GM original opti I checked the rotor position of it and compared to the spectra opti that was installed .. rotor was in the wrong position by about 1/4 inch so then the code is thrown.

this CODE does not effect engine performance it is only used to report the position of the cam to crank but the problem is the timing will be off if this is not manufactured in the proper position .

there are many highly qualified GM tech's , but not too many still around that have the skills to deal with these engines . so did the tech place the engine @top dead center and check where the rotor sits ?

all it takes is 1/4 inch off.

 

I checked the rotor position of it and compared to the spectra opti that was installed .. rotor was in the wrong position by about 1/4 inch so then the code is thrown.

so did the tech place the engine @top dead center and check where the rotor sits ?

all it takes is 1/4 inch off.

Wouldn't that be detected by a scope though? He scoped it and said it is right on the money . . .

I know he said he double and tripled checked the timing chain, hand cranked to TDC, and I assume he made sure distributor was on the mark at that point, but I didn't specifically ask him about rotor placement . . .

My question is, if it was 1/4" off, wouldn't that be picked up by the scope? Engine is running perfectly . . .

 

well if the opti is off and this code 336 is on ,, the pcm will adjust the timing to compensate for this maybe ..

if the timing is off a few degrees advanced probably will not notice any issues on engine running .. if the timing is retarded slightly could run hotter and less pep ... depends on how far off .. now others have installed the opti on wrong and had this code also ....

I did this check on the opti many times and I did check this very carefully and it was off rotor 1/4in from OEM ac delco opti that is in there now compared to those spectra opti's... I did this 3 times installing removing measuring it was off ..

 

I'm not sure about the adjustment of the timing part of your first sentence . . . everything I've read and researched on this suggests that the CKP for the '96 is a glorified misfire reporter, and is static and does nothing as far as using its data to make adjustments and control timing, unlike other actual, real CKP sensors which do actually help control timing . . . please someone correct me if I'm wrong on this . . .

Other than that, this is the only place I've heard of regarding the 1/4" rotor offset for aftermarket opti's as far as P0336 code . . . I guess I'm just shocked that it could be off that much and run fine . . . but I suppose it is possible . . . I'm still up in the air regarding it, but do appreciate your experience / insight as a final place to go / final thing to try before having my tuner just delete the stupid code altogether . . .

 

I did this check on the opti many times and I did check this very carefully and it was off rotor 1/4in from OEM ac delco opti that is in there now compared to those spectra opti's... I did this 3 times installing removing measuring it was off

How many degrees does this change the spark advance in data logging?

In OBD1 in the constants table there is "Spark Reference Angle". I thought this was used to adjust the TDC point of the cam to the OPTI position. Is this correct?

Is there a similar adjustment that might help adjust the cam/crank miss measurement in OBDII?

I am not trying to defend bad manufacturing but if the PCM gets the correct cam position the distributor rotor seems large enough to allow normal operation.

 

If the shaft set in the cam key is wrong,,,,,,,,,,, then the encoder wheel slots will be in the wrong position then the optical sensor gives the pulses to the PCM which will pulse in the wrong position then the PCM timing control will be off. so if the rotor is off so will the encoder wheel then the code error ..

if the error is intermittent this is a miss fire that the PCM will sense so you only get a p0300-8 code......... ,, if it continues constantly then the PCM knows its a mechanical problem not a miss fire .. so you only get a 336...