Crank Sensor Question

[JHensberry]

Is there a way to tell if the crank sensor is bad? Once the car starts is the crank sensor out of the equation? Just changed mine, service manual says .025 for int. ring gap, instructions said .020. I got the .025. Anyway still having the same stumbling/surging when the car goes from drive to overdrive around 50 mph. Replaced cam sensor not to long ago. I have a FP gauge but not one to put to the windshield. This happens when I am just cruising, seems to smooth out about 65-70. May look at coil pack/module next. Thanks, Joseph.

[Keller]

Cam sensor really only used on a cold start. Not really referenced later. And if it failed, the car would just go to Code 41 and multi-port mode. Possibly not restart. See http://www.gnttype.org/techarea/ecmsensors/camsensor_FAQ.html

Crank sensor on the other hand is critical to timing, I believe. Could actually be TCC sticking closed, failing fuel pump, bad chip, or something else.

Have a scan tool?

[kenmosher]

Cam sensor is used all the time for sequential injection ... it indicates when to start the sequence (window indicates #6 is firing).

The crank sensor is used for every firing event ...since our system is waste spark, each coil is fired (a pair of cylinders ... one on intake and the other on exhaust) and the appropriate injector fires for the intake cylinder.

If the cam sensor fails with the car running, the ECM will set a code and then start firing all the injectors each time the crank sensor fires the ignition. This will keep the car running, but if you shut it off, it won't restart (since the ECM can't find "synch").

[JHensberry]

yes have a scan tool. the only thing out of sync is the low blms and the high lv8. the fuel pump, Walbro 340, I think, is maybe 3 years old w/ very few miles on it. It makes a whining sound, for about 8-10 sec., then goes to lower pitch for a half second then back. The hot wire made the whine alot less. The TCC solenoid does as it is supposed to when you hit the brake in overdrive with the gas pushed it should rev up, it does. The only other chip I have is for the 28# stock inj/28# street on chip. Thanks, Joseph