Hi, I've tried several things on my 2001 Olds Silhouette mini van. I've changed each coil in turn, replaced wires and plugs. I've taken the module to Autozone to be tested and it comes out okay.


The misfire is very noticable at tickover. Not so much when running, but I think it's still there. It has the sharpness of an electrical fault, but not to say it is.

Starting is like the engine 'falls over itself.' Horrible, like too advanced. It used to run like any other car until AAMCO had the transmission out 3 times to get it right! Every time, loads of remedial work to tidy up.

I've scoped the crank sensor and got a good wave from it, though the blog I saw said: .3 - .9 v I got ten times that: 3 - 9. I thought he must have made a misprint, but I don't know for sure. Anyway the wave was constant.

Code readers have shown a missing on several cylinders, but it's not constant.


Where do I go from here? Any help appreciated. R

 

Nearly a month later I'm still looking! Have a go at it, then just use it as it is, but I hate things not being right.


I've had masses of help, but no answer. The camshaft sensor gives an output, but it is the WRONG WAY UP. Reading zero volts, then going to 10-ish in the square wave. Haynes and everyone else seems to think it should be 10, dipping to zero for the pulse. The OBD reads camshaft detector, but this can mean the comparison with the X3 output from the ignition control unit.

Anyone know which way up the cam signal should be before I remove the darn power steering pump to get at the sensor? Even then, I kind of doubt it's going to be the answer.

 

Be careful with interpetation of codes. What is the camshaft code you are getting? I take it you are using an o scope as to see the voltage change. I am not sure if the module reads a sine wave, then converts it or what. The module could raise the wave, then clip it.

 

Kevin

P0341 cam sensor - can also be a relationship between crank and cam I think the reader said. (It's had three expensive readers on it. $ 5 - 8k the owners tell me. ) One reset the relationship between cam and crank. That worked for about ten minutes. This intermittentcy is driving me nuts.

The crank has a sine (ish) wave, but the cam sensor puts out a good shaped square wave. I'm using a Tektronix dual beam, but of course without an inverter and a lot of messin' I can't take it for test drives as recommended.

Yesterday, in a garage at 100f, I tried to get at the cam sensor. Haynes says lay the PS pump aside - no need to undo the pipes. I tried for half an hour to wiggle it out without stressing the pipes. Just could not do it.

I used a probe and air to clean the top of the sensor. Just about see it. On the rebuild I noticed I had no warning light on. It's happened before, so not too excited about it. Anyway, first drive the car was sweet, better than I can remember. I stopped the engine and restarted, and it was still okay. Then suddenly the service light came on again, and tickover was back to really rough.

One bit of skilled advice said ride with the scope and record. Look at the traces with care later. It only takes a moment's break to upset the cam pulse's relationship to the Ignition X3 pulse - and or Crank. (which probably is carried by the X3 signal from IGN to PCU.)

That X3 pulse I've checked right to the CPU. It looks good.

Continuity checks of the wiring I've done while shaking the loom about.

Feeling a bit defeated, and guess it's time to start throwing parts at it. Bit amateurish, but heck, that's what I am.

In 55 years of messing with cars, this is the most subtle fault I've had to tackle.

For anyone interested, a blog on PpruNe shows the photos of the PCM's innards. One chip looking seriously heat stressed. That will be number 2 part I guess. $200

Pictures are in the later posts. The masses of verbiage says no more that I've said here, really.

http://www.pprune.org/jet-blast/4881...yone-help.html

 

I'd hate to think the pcm was breaking down, but if the signal from the speed probe is good, I don't know other than that. It thinks there is a mismatch, works for awhile, then cuases problems. You are reading the signal at the pcm? Since you gone this far, I'd suggest pull both ends off, and close loop the two wires, then check resistance, as you stated while shaking the wires..

 

As I mentioned, I drove the car and it was the best it had been for a short while. I'd been cleaning the top of the cam sensor (that I couldn't reach to remove) and wondered if I'd jogged anything. But it only takes a moment's break to trip the warning and run rough. So, since I can't scope it on the run, I thought I might listen to it.

There was a guy on the Cadillac forum who put loudspeakers on his STS suspension. This way he could monitor the mark/space ratio by tone! I though I might do the same with the signals. If it fultered and the SE Light came on, I'd be fairly sure it was the cam signal and be worth pulling the PS pump. However, my money's on the PCM. The heated chip and the time factor. Just about right to get hot then fail.

What was fun is now a chore. Need to get it right soon, but the smooth drive was encouraging.

 

Does it run well at all after cold? I still think pcm.

 

I don't know where you are located, but if it where me, I'd replace the CPS while I was at it. These run (here) around $35

 

Kevin, I agree, I've got one here, but it's just the trouble of removing the Power Steering pump that is the issue. Haynes says lay it to one side with pipes on, but I failed to find a way to get it out from beyond the front casting, and believe me, I tried. It may be possible, but I don't want to fracture the pipes. I may well empty the system and pull the pump, but just another job I don't need right now.

So, testing it to a new level seemed the lesser of two evils, but even then, I can well imagine fitting a new PCM and then it failing shortly after.

Anyone with the knack of getting the pump to one side with the pipes on, let me know.

 

Try searching on you tube for this. I fixed an injector on my lumina watching a "how to" vidio.