P0340 - GM

Question

I have replaced the Camshaft postioning Sensor 3 times in 2 weeks time. I thought that I might have been getting a bad batch of sensors. NOT AC Delco..
Car run a little rough..Sometimes hesitates, gas mileage BAD.
Have OBDII Meter and I drove car with meter on and noticed when I lost power the meter was shown no advanced spark. B4 I lost power I had at idle 598rpm approx. 18-20 deg adv. Now it's showing 0.
Started (97 Chevy Blazer 4.3l) tghis morning with no problem and I have cam advance..
What gives? I clear code and drive a bit = aok. Shut off car. Later get back in and start it and Check engine light comes on and meter show P0340 again. BUT run ok and I have cam advance for awhile soemtimes 2-4 days the loose it again. NO SPARK ADVANCE!..

Answer 1

Hi there,

You may have a mechanical timing issue, a wiring issue to the cam position sensor or a faulty pcm. I would do a compression test on the engine to determine if the timing is off or not. Possibly check the timing with a timing light if it's possible on this model.