P0336 crank sensor and opti problem:

[Fatman27]

Ok, here is my saga. Hopefully someone will find it useful in their troubleshooting efforts.
I blew out my Optispark driving through some large puddles in a rainstorm. Finally saved enough bread to purchase a premium, DragonFire OPTI from All-Ignition.com for $300. Put the new OPTI on and worked OK except that once it got warm, there was a noticeable miss at all RPM levels. Also got an immediate P0336 (crank sensor reading failure) DTC error code. I replaced the $40 crank sensor even though I doubted it was the problem and sure enough it wasn't.
I could have troubleshoot it more effectively by merely pulling the electric connector on crank sensor and saw an immediate P0335 error code (also a CK sensor failure). Plugged it back in and P0336 error code pops right back.
After doing more troubleshooting of ignition wires and tighten the sparkplugs (most were slightly loose since I had put WD-40 on the threads 3 years ago when I replaced them) still was having the ignition miss and P0336 DTC.

Finally, after reading several of the excellent posts in this and other forums, I realized it was likely the OPTI not sending the proper low-resolution signal back to the PCM. (The PCM compares the signal from the Crank sensor and OPTI low-res for misfire detection) Fortunately, I got All-ignition.com to replace my distributor with another one -although their testing did not indicate any problems with the original OPTI. However, I'm not sure they even had the capability of testing for proper low and high resolution signal outputs from the OPTI. My new distributor works better - no ignition miss and no P0336 DTC, plus I had the joyous opportunity to change the OPTI again!!

PS: The DragonFire seemed like a good alternative to the $500+ MSD, especially since it uses the same optical sensor, but I sure could have done without having to swap the distributor a second time.

[Danger731]

wow just read this doin a search , what a pita !

[brianswimmer23]

sorry you had to go threw all of that crap, i had the same issues using MSD when i changed my opti for the first time(wont be doing that again) i only use AC DELCO opti's not and since i have had my new engine with an AC DELCO opti have had no issues!