I have a 2002 Blazer AWD that I have been slowly taking care of all of the issues on that have been keeping it from being a reliable second vehicle. I have done the all the usual maintenance, Dist. Cap, Dist Rotor, Plugs, Plug Wire, Fuel Pump, Upgraded Injector Spider all with Delco parts. Lower Intake Manifold Gasket Set and Valve Cover Gaskets with Fel-Pro gaskets. Right now have it running well. Now down to throwing a P0335 when accelerating aggressively, half throttle or more, it will throw a P0335 and the tach will jump past redline and back quickly until I let off. I believe the tach begins to jump above 2500-3000. I am getting a few misfires on random cylinders at idle cylinders 4 and 5. They are not felt misfires, put ODBII sender with Dash Command shows them. It is my understanding that this may be incorrect if I have invalid Crankshaft position readings because I need a CASE Relearn. The P0335 only shows up with aggressive acceleration. If I drive normally, it will eventually reset the SES light. I am questioning the need to do the following.

1. Buy a new Crankshaft Position Sensor, have the CASE relearn completed and then adjust the CMP Retard to spec.
2. Have Case Relearn completed and adjust CMP Retard to spec.

Does the P0335 only show if the Crankshaft position sensor is bad/bad wiring or will a CASE relearn clear the code?


Any advice will be greatly appreciated.

 

A P0335 is no crank sensor signal for >3 seconds while a cam sensor signal is still being observed. Certainly this would be felt as no crank sensor signal should equal no ignition pulses. If you have Dash Command, what does a live tach displayed indicate for RPM during the observed problem? A few misfires observed on scanner is not an issue, as it takes quite a few steady ones to set a misfire code. Or maybe it is actually hitting the sensor at speed. But I would think that should really whack it out and cause a running problem. I suppose you could remove it and look for scrapes.

I would clear the code using Dash Command and see if it returns.

 

Followup. Shimmed the Crankshaft Position Sensor and this got rid of the P0335 code and the tach is working perfectly. Additionally, the transmission seems to shift much better now.


Need to do the CASE Relearn and set the CMP Retard and call it good for now. Code free and hoping it will stay that way for a minute. Now on to the shake at higher speeds.

 

CASE Relearn has absolutely no affect on how the vehicle runs, as long as the SES light is off. It's entire purpose if exclusively for misfire detection. I would pull a plug wire or two (one at a time) and if it correctly identifies the misfire, and you can see the counts adding up on a live scanner under the correct cylinder - then no need to spend the money on a CASE relearn.

The cam sensor retard, however is very important to how the engine runs as this is a functional measure of where the rotor is pointing when the cylinder fires.

Glad to hear you are making progress.