I just received a P0336 Cam Position Sensor Performance OBD2 code on my '98 Pontiac Grand Prix 3.8L K, what tools do I need to reset the timing?

Asked by Mar 18, 2014 at 12:21 PM about the 1998 Pontiac Grand Prix 4 Dr GT Sedan

Question type: Maintenance & Repair

While driving, attempting to pass another vehicle, the acceleration hesitated. I
tried acceleration a few more times afterward and the same thing was
happening, then soon after that the engine was chugging, or running rough,
acting like it was going to stall out. I parked it and checked all the spark plugs
for moisture to make sure it wasn't a gasket leak issue into the intake. No
moisture was found, so I polished the deposits off the plugs and re-installed
them. I haven't tried to turn it over yet since then. I would like to check the
timing while I'm in there, under the hood. Do I need a pully puller for this job? I
have most other common tools. What do I need to remove to get to the chain?
My block is still covered with old oil leaks oil, so it's not too clear if I need to
remove water pump or not 1st. I wish there was a timing mark on the belt pully
so finding Top Dead Center  and making the alignment wouldn't be so difficult
or seemingly difficult. I mean, this would tell me right away to go deep.
The only picture I have right now is of the #6 (firing order, Left Bank near
firewall) spark plug. It had heavy dark brown deposits and two of the four ends
were closer to the insulator than normal where deposits may have started
Gap Bridging, leading to a dead cylinder or no fire. I did not receive any miss
fire codes, however I had a reading done as soon as I thought I may not make
it home. I do not know how long it takes for a fault to trigger a code.

7 Answers


You cannot "reset" the timing. The Engine Control Module sets the timing based on the cam and crank sensor signals. The symptoms point to a bad CPS, and the OBD is kicking that code out as well, so that's where I would start. BTW, rough idle, fouled plugs, poor performance, are all signs of a failing CPS, so it might have been going bad for a while.

2 people found this helpful.

I replaced the Cam Position Sensor and cleaned all deposits off the spark plugs and nothing has changed. I played with the wiring while it ran and nothing changed. I drove it about two miles to the gas station and back and nothing changed. it's still loping like it wants to stall and occasionally, for about 3 second spurts, it runs fine. I plan to do a more thorough check on the wiring though.

Also , while driving , acceleration is back to normal. It's no longer hesitating.


Good job on the cam sensor, it needed to be eliminated as a source of the problem. Make sure the crank sensor is reading properly as well. Your engine has a timing chain with a chain tensioner, not a belt. These are the next things to check once you know that the cam sensor and crank sensor are working correctly. A worn chain or tensioner will also cause the problems you're having. Both are inexpensive items, and can be replaced by backyard mechanics with some experience. http://www.ehow.com/how_7915451_change-grand-prix-timing-chain.html

3 people found this helpful.

I eliminated the wiring itself as a fault. All are good signals coming through the wires. Crankshaft position sensor is the next test then onto checking the chain, tensioner and sprockets for play and/or wear.

Update: today I just replaced the crankshaft position sensor, put it all back together and drove it to AutoZone where I had them code read it. I didn't clear the code since work was done and they wouldn't clear them for me so I disconnected the negative from the battery for about 20 minutes and upon starting her up the MIL light came back on immediately upon starting and stayed on. I opened the hood and took all the wiring to the cam and crank position sensors and to the ignition module off and inspected them pretty good. Nothing was burnt, melted or severed or exposed. Now I'm starting to believe that either the crankshaft lobes are worn or the crankshaft bearings are worn because at stoplights it sounds like it's knocking. When just idling it's losing power randomly as if ther were a dead cylinder. I have yet to get another OBD2 read on it but so far only P0336 surfaces. I was told it could be a bad ignition module also, so off to a junk yard tomorrow to find one and cross my fingers that it's operational. I'm going to be a street musician full time if my car dies, I'll never get another trade job on foot!


Ok, after talking to my GM mechanic, I received pertinent info on typical problems with my make and model. I ended up buying a part from a junkyard for less than $20 that cured my problem and seemingly has nothing to do with the P336 code, SEEMINGLY. This means that there is still a bunch of variable info known by industry professionals that never get printed into the over the counter repair manuals nor the online manuals that come without a college degree. If you would like to know what part I replaced please email me directly ant12xox@yahoo .

1 people found this helpful.

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