GM HFv6 2.8 - P0341 Intake Camshaft Sensor Bank 1, performance problem

CLOVES

MEMBER
2007 SAAB 9-3
2.8L
6 CYL
TURBO
2WD
AUTOMATIC
82,000 MILES

I had a p0341 camshaft sensor from bank 1 code. The camshaft sensor on these is a hall effect 3 wire sensor. Checked the wiring for power, ground and signal and had no issues. I then replaced the sensor, code came back after clearing with a tech2. I then hooked up an oscilloscope to review my waveforms. The reluctor wheel on these engines have 2 short teeth and 2 large teeth. I noticed in my waveforms that I had an issue with my larger tooth.

I then inspected the camshaft hole and it appears that one of the larger tooth's has a burr on it. Its not missing a chunk but has that burr. When I hook up my tech2 to the car I can test the intake cam angle on both banks. When I test bank 1 (the one with the code) I get no changes in the angle. That could be a result of the code being set and the ecm using default timing on that bank. This is a VVT cam phaser engine.

Any thoughts on what could be the issue here. I know these engines, which are similar to the 3.1 and 3.6 in CTS Cadillac's, are known for time stretch issues. Usually it is a different code.

Car seems to run fine aside from the dtc code.

Video of my camshaft waveforms. Top blue is bank 2 which is okay and bottom yellow is bank 1. The second large tooth shows an issue on the scope.

Youtube of waveforms:
https://www.youtube.com/watch?v=KjcKs-ciVg4&feature=youtu.be

Intake Cam Angle Test:
https://www.youtube.com/watch?v=Gd3lbV1j1SI

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3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

This would indicate an issue on that bank. Just so I am clear you are getting the code for Bank 1 intake cam but you found this on bank 2 of the intake cam? Is there a chance that you got your banks backwards? Have you inspected Bank 2 like you did this one when you found the burr?

Reason is, this scope pattern reflects exactly what you are seeing on the cam. Having a burr on this tooth will cause an erratic reading on the scope. This is because the sensor is simply picking up the highs and lows which produces your voltage reading. If you look at the attachment below, it is as you stated that the second long tooth is missing so it picking up the rising and falling edge but missing the middle. A burr or chipped/cracked tooth will cause this.

Also, I am very excited to see you are using a scope. It is rare not only on this site but in the industry in general that techs will use a scope.

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Tuesday, November 12th, 2019 AT 4:36 PM

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KASEKENNY1, thank you for the reply and your markups! To clarify, the bur is on camshaft bank 1 which is where the error code is pointing to. The bur is so slight that it really makes me wonder if it actually is the cause of the DTC code. I took a look at the saved video of the waveform and part of it shows the large tooth issue but a few seconds later the tooth shows up fine (as illustrated in my image). I am still questioning if the burr is the cause, its so slight. I also crudely tested the reluctor wheels plane by attaching a wire and turning the engine, the wheel seems to be on the same exact plane all around.

The other camshaft sensor tooth looks fine, no burrs. I am left questioning, did something hit that reluctor wheel and cause that tiny burr or has it been there since factory assembly? Which then leads me to ask, why would it all of sudden cause this error. People continue to say it could be the timing chain jumped a tooth and/or the timing chain is stretched, but I fail to see how that would affect the camshaft waveform.

Your illustration shows the full camshaft wheel and reluctor, I am wondering if perhaps something is wrong with the full wheel and I should replace the whole thing. I have been unable to find just the reluctor wheel as a separate part.

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Friday, November 22nd, 2019 AT 2:36 PM

KASEKENNY

MECHANIC
18,907 POSTS

Okay. Unfortunately, I think that burr is more than enough to cause the issue on the pattern. I suspect the pattern returns at times because the sensor is able to pick it up but it is not consistent. I am the one that doesn't pass over things like this if it is pointing at the issue. We can only correct what is in front of us and then look further if that doesn't fix it. Basically solve the problem that you know exists and then go from there, rather than trying to think past this issue. In other words, keep it simple.

If it were me, I would fix the tone wheel issue and then go from there.

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Friday, November 22nd, 2019 AT 6:04 PM