P0343 Error, Have checked/tried everything, CASE relearn the cause?

[noskcaj]

Just finished up building and swapping in an LS1 I built for my 240sx a couple weeks ago and recently a P0343 error has popped up.

By what I researched this is due to the computer seeing the cam sensor signal staying high when it should switch. It could be caused by bad wiring, bad sensor or cam bolts loosening. I followed the troubleshooting guide and have determined the following:

- cam sensor is getting proper +12 and ground
- Jumpering to the signal from +12 causes cam high-low and low-high to increment in EFI live
- cam sensor is brand new and not touching cam
- Checked cam bolts and retaining plate
- Oil pressure good (50 psi at idle)
- Tach output wire works fine with 240 stock tach
- engine is hard to start sometimes, pops and hunts for what stroke its on, and other times starts immediately
- when checking cam I also verified cam relector was centered in cam position sensor hole. (the two alternating reluctors were centered, not sure if this is right or not)
- cam is an MS3, timing chain and sprockets are new LS2.

The only thing I can think of is that the PCM needs a CASE relearn. I have not tried this yet since I have to wire up the P/N and E brake inputs, but I'm going to try this next.

Thanks!
Eric

[joecar]

Hi Eric,

Is the cam position (CMP) sensor wiring damaged...?
Is the CMP signal wire swapped with the reference wire...?
What CMP sensor are you using...?

Can you see an AC voltage on your DMM on the CMP signal (or better yet, if you have access to it, an oscilloscope waveform).


CASE relearn won't affect CMP conditions, but you can do it anyway.

[joecar]

...
- when checking cam I also verified cam relector was centered in cam position sensor hole. (the two alternating reluctors were centered, not sure if this is right or not)

The cam position (CMP) reluctor is just a single x1 reluctor...

the crank position (CKP) is 24x dual inverse reluctors...

are you sure you were looking at the CMP sensor/reluctor and not the CKP sensor/reluctor...?

Post pics showing where on the engine you were looking...

[noskcaj]

I believe the cam sensor wire is ok since the cam sensor high-low and low-high pid's increment when I jumper to batt

The cam sensor wires are in the correct orrientation according to all the pinouts I can find online and I confirmed ign is +12, ref is gnd and jumpering increments the pids for the signal wire.

The CMP sensor is one for a 2000 camaro, its located in the back partially under the intake

I do have an old scope that I can play around with, but I havent used it in ages, hahah. I'll try using an dmm with ac to see what the sensor is sending. I am also thinking of turning the engine over by hand and monitoring what the sensor is doing.

I guess the way I was describing the reluctor was a bit confusing. The reluctors on both of the ls1 cams I have seem to have two ridges that are opposite by 180 degrees. This picture shows what I'm trying to describe, haha. Its definitely a 1x reluctor, but the switching of the hall effect sensor seems to be more complex than I thought.



I also read a thread in another forum about the wheel being machine incorrectly and this was causing a p0343. I'm thinking turning over by hand and watching the output and maybe spacing the sensor very carefully and see if the signal changes. Fortunately it only causes the car to start slow.

Thanks for the help troubleshooting this thing!

[joecar]

Yes, that pic shows the 1x reluctor on the rear of the cam.

Yes, see if you can correlate the cam signal with the crank signal.

See attached pic (copied from Autonerdz).

[jb35007]

i have a problem with the cam reluctor not being centered?? anyone know how to fix that???? it seems to be to far toward the rear of the engine. the sensor is good but doesn't read any change in the reluctor.... plz any input would be appreciated.

[joecar]

Post pic of old new cam side-by-side with new cam.

[jb35007]

Post pic of old new cam side-by-side with new cam.

this is the only cam i have... this cam was in the engine before i rebuilt it, it is a flowtech cam and it worked before the rebuild? if the hole where the sensor was set up on a grid and the relucktor should be at 5 on a scale 1-10 then the reluctor is at 8 1 being toward the front of the engine and 10 being toward the rear

[jb35007]

here is a pic as you can see the roller lifter is not riding the cam lobe in the proper spot???? anyone have a clue on how to get it right????

[joecar]

Is the cam sprocket loose...?