I was wondering if the crank posistion sensor could cause the notorius high load low RPM stumble/backfire problem?

I say this because I forgot to plug the CPS sensor in and the car was poping and backfiring. I drove it for about 3 days untill I could get a scanner to read the codes.

what is the chance that the CPS is faulty but not setting any codes?

Could someone do an experiment and unplug the CPS and try it out? (6th gear, 1100 rpms, mash the gas)

 

Sorry but i am pretty sure the CPS is only used for diagnosis and doesnt affect anything else.

However i hope i am wrong becasue i have a 93 engine (no CPS) and a 97 computer and have that high RPM stumble. I hoping new injectors will cure mine

 

I read on another board that the CPS and the Opti compare readings... But this is purely hearsay

"The way the cps works is there are four notches on the reluctor, one for each crank throw. There are also four windows on the wheel for the low res sensor in the Optispark. The computer expects the two to agree with each other. If they don't, then it assumes the Opti is correct, and it sets the code P0336."

 

Also, everyone says the CPS doesn't do anything... I would have to disagree, unless it was by coincidence that my car was running strange and backfiring until I plugged the CPS in. Can some one (with a RUNNING LT1) try out my theory?

 

It doesnt do anything, I ran my 96 with no cps at all (swapped in 94 motor) for about 15k before i went to obd1. The only thing the cps does is detect misfires.

DO NOT mash the friggen gas in 6th gear at 1100rpm . That is a recipe to ping the living hell out of the engine. Its probably backfiring because its pulling a crapload of timing out of the engine. Try picking the right gear if you want to mash it and you wont have the problem .

 

Gee, thanks for the help! My stupidity must be the reason there are numerous post about poor running motors.
I agree, 1100 rpm-WOT not a normal operating procedure, but the actual problem was at WOT in 6th gear at 55 MPH, the car SHOULD be able to handle that situation (i think) without missing.

 

I had those exact symptoms and mine was an O2 sensor that had melted the connecter to my header and was shorting against it. Fixed that.... Then it was an injector stuck open.

 

But there are 8 "windows" on the Opti low res portion of the wheel. The cam turns at 1/2 the crank speed, so is all makes sense. The diagnostic codes are set based on the duty cycle of the CPS signal.

 

Injuneer, so do think it matters if the CPS is their or not?

 

I never owned in OBD-II LT1, so I have no idea. There seems to be a lot of people who have run with the CKP codes and not had problems with the engine running rough or down on power. On the other hand, a faulty Opti can cause the CKP code to pop up.