Hello,

newb jumping into the fire!!! I've done tons of searches and read lots of information regarding cam and crankshaft position sensors. I installed new plugs, wires, and checked the coils. All the even cylinders are fine. On the odd side, I can't get them all to fire. Most of the time, 1 cylinder will fire and 3 wont. At the moment, cyl 3 is firing and 1, 5, 7 are not. A few times, 2 were firing and 2 not. This happens at any RPM up to about 2800 which is as high as the motor will rev with the condition. I did a scan and 0300, 0340, 1138, and 1316 display. I removed the cam sensor, cleaned, reinstalled and issue didn't change. I still have to do the same for the crank sensor.

Most of the issues I've read with cam/crank sensors happen while accelerating and the engine will cut out. Mine does it at idle and I can't get it above 2800 RPM. I hook a timing light up to the odd plug wires and I don't even get a flash once in a while - completely dead. I figure the computer is shutting them off, just don't know why.

What's everyone's thoughts? Could it be a bad cam or crank sensor. with P0340 coming up, what are the chances it is the cam sensor and would it happen at idle?

Thanks,
Dan

 

Move the known good good coils with known "bad" ones.
Does the issue move?

 

340 is cam position sensor circuit malfuntion. See attached. The CMP is a sensor with a backup plan. You should be able to unplug it and engine run. If no change, perhaps sensor is already bad and engine is already running on plan B. The CMP produces 12 volt pulses which can be read with meter or scope back probed at connector or at the ECU.

 

I swapped coils early on when cyl 3 was firing with cyl 5. Cyl 5 still didn't fire and I also lost cyl 3 - kind of strange. At one time none of the odd cylinders were firing. I also read that when a coil pack fails, the matching even cylinder should also fail due to one coil controlling an even-odd pair?

I have a USB oscilloscope - I'll try it out tomorrow. If I get a consistent waveform does this mean it's OK if my trigger is 12V? I'll also try unplugging it.

One more thing, I have a 95 that is OBDII with a 4.0 (VIN Z). It appears that 95 was a transition year and early 95s didn't have OBDII. The cam sensor for the 95 OBDII has a slightly different connector then the 96. Are they functionally the same? If I splice/solder/shrink wrap the old connector on the new will it work ok? 96+ version are readily available while the late 95 version isn't.

 

I don't know exactly why, but it's running on all 8 cylinders now. I had it running with the 3 missing cylinders and my son was checking fuses because the OBDII port wasn't powering up the scanner. He pulled the engine management fuse without me knowing it, the motor died as I would expect, but when I fired it back up it was running on all cylinders!!

I guess I'll move onto other issues and not worry about why.

Thanks,
Dan

 

Whew!!!
Glad I could help. lol
Its working now, dont question it.