Jumped the gun still having stumbling issues

Cam sensor is located on the driver side head, just below the mating surface for the cam cover. The sensor plug connector is by the brake booster.

[bobbyhi]

It is one (1) bolt holding on a metal shield. Take the bolt out and remove the sensor. Put rags under the hole as a little oil will drip out. I don't know how to test. The end of the sensor should be magnetized. Try to pick something up. I used a razor blade and it would barely attach. Maybe Jeff knows how to test correctly. I replaced with a used sensor and it only stumbled at 4000 rpm once today. They are a pricey item to replace. Somewhere in the $300.00 bracket. I still don't know if this fixed my problem. I did take out the Accel coil packs and replaced with GM. Don't know if it helped or not.

Good luck and keep us posted!!!

[XfireZ51]

Jeff,

Looking at a =Jeff= scan, his O2 sensors are hardly moving. They sit there at .45v. Both of them. He goes in and out of C/L but is mostly in OPEN although his BLMs change???. Learn control is OFF. Also Diff MAP registers a constant .6 volts but when he stabs the pedal,voltage goes up and Scdys Open. I suggested he put original chip back in and see aht happens. There's no SES.

[-=Jeff=-]

Originally Posted by XfireZ51

Jeff,

Looking at a =Jeff= scan, his O2 sensors are hardly moving. They sit there at .45v. Both of them. He goes in and out of C/L but is mostly in OPEN although his BLMs change???. Learn control is OFF. Also Diff MAP registers a constant .6 volts but when he stabs the pedal,voltage goes up and Scdys Open. I suggested he put original chip back in and see aht happens. There's no SES.

Original PROM...


NO CHANGE

[bobbyhi]

Originally Posted by bobbyhi

It is one (1) bolt holding on a metal shield. Take the bolt out and remove the sensor. Put rags under the hole as a little oil will drip out. I don't know how to test. The end of the sensor should be magnetized. Try to pick something up. I used a razor blade and it would barely attach. Maybe Jeff knows how to test correctly. I replaced with a used sensor and it only stumbled at 4000 rpm once today. They are a pricey item to replace. Somewhere in the $300.00 bracket. I still don't know if this fixed my problem. I did take out the Accel coil packs and replaced with GM. Don't know if it helped or not.

Good luck and keep us posted!!!

Just an add to my post:

I didn't have any SES (codes) until today before I switch the cam sensor. The code was for faulty cam circuit. The stumbling occurs when gentle acceration is applied and at around 3500-4000 rpm it starts "missing". Key on or key off - still did it. The it would go away and not happen for a couple of days. Only happened when the engine was hot. Very perplexing!!

[XfireZ51]

bobby,

So you finally got a cam sensor code?

[LGAFF]

Jeff, I doubt I will be running my car this weekend, if you want to come over and try my cam sensor on your car before you dump $300 let me know.

LGAFF
92 ZR1
#234

[XfireZ51]

Originally Posted by LGAFF

Jeff, I doubt I will be running my car this weekend, if you want to come over and try my cam sensor on your car before you dump $300 let me know.

LGAFF
92 ZR1
#234

Lee,

I just offered him my ECM since I'm out of town this weekend. However, I have to say that a cam sensor shouldn't make the scan look the way it does. There are a number of contradictory readings on the scan. Although the ECM says the system is in O/L, the BLMs are changing. Both his O2 sensors read .45v constantly. No X counts. His secondaries are opening even tho his diff MAP shows .6 volts. Something is screwed up.

[-=Jeff=-]

I have an ECM on the way tomorrow, will have it next week.. switching it no matter what.. did some Service manual reading..

the O2s are Biased to 450mV by the ECM, the O2 sensor then helps to adjust up or down (rich/Lean) there are 2 signal inputs to the ECM Left and Right O2. There are also 2 Ground pins on the ECM for left and right O2.. which are shorted together and then grounded to the engine. I ohmed between both Left right grounds at the ECM.. confirmed short... Ohmed from both to ground ( both chassis and engine) seems to be open.. I ran a new wire to creat the ground.. it is later here and I will nto get a chance to try again until saturday AM..

So that might explain the O2 problem, but not the changing BLM in Open loop..

[XfireZ51]

Jeff,

Sounds likke you still need to fix that open ground regardless. I would fix that first before installing new ECM and see what happens. Is the O2 ground tied into an ECM ground by any chance?