I have a 01 zr2 blazer has a misfire p0300 won't let itself shift to overdrive when light flashes got cmp retard set to 0 still wouldn't lock up torque converter you can't feel the misfire but the computer detects it if I unplug the cam sensor from the back of the distributor check engine light stops flashing and the Blazer will go into overdrive on the highway like it's supposed to any help would be great I believe my crank sensor is being hit by the reluctor wheel because if I floor it the tack will go crazy at about 3,000 RPMs just don't know if replacing it will fix the overdrive misfire issue

 

This thread was missed because of where it was posted.

Either it has a misfire when the light flashes or it doesn't. Since ignition is run off the crank sensor, hitting it on the reluctor enough to affect tach signal should make a definite misfire. Have you been playing musical crank sensors or musical PCMs without doing a crank sensor relearn? Sounds like false misfire detection to me. A number of other things can cause it as well.

PCM definitely disables the TCC when a misfire is detected. Unplugging the cam position sensor prevents it from detecting misfires

 

See post #32 here for some more info: https://blazerforum.com/forum/2nd-ge...-104363/page4/ and note attachment to that link describing other things causing false misfires.

 

For future threads please start one like this in second gen or engine/transmission general forum. It will get a lot more attention. Please punctuate your sentences - makes them a lot easier to read..

 

Thanks I did end up posting to that section right after I posted here just didn't know how to delete this one. I set my cam retard to 0 with a sbc hold down and just unplugged the cam sensor it drives normal I think I need a crank shim cause if I floor it once it gets to about 3000rpm it will bounce and not shift till u let off a bit but normal use of the gas pedal drives fine sometimes it seems like it cuts out for a half second but then continues driving normal haven't changed the sensor yet because it's cold out and I don't have a scanner to do the relearn am I hurting anything driving it the way that it is

 

Possibly the catalytic converter if there is really a misfire. Otherwise I would say nothing else is being harmed. However I once had some bad bearings causing false misfire detection and the light to flash, but they made some noises and oil pressure was bad when engine was fully warmed.

 

What do bad crank bearings sound like. Not sure I know the sound tick knock bang?