vw beetle P0341 [FIXED]

hi,i have a very tricky case here,
VW Beetle 1.6L BFS engine,
the P0341 code = G40 camshaft position sensor circuit Range/Performance
i have checked the following things
- sensor 5v
- sensor ground
- sensor signal
- valve timing is good
after i erased the trouble code when KOEO,the code doesn't come back.
but it immediately pop up after i started the engine.
the attacment is the waveform that i captured (cam sensor signal)
looks like i have a very clear squarewave that we we want.
but i was wondering if the interferences voltage spikes could be the cause of this issue.
i have found out that this spikes are from ignition voltage spikes.
is this normal?or this could a sign of something went wrong.
i don't want to ask the owner to change the plug cable and ignition coil,since i am not sure about this.
hope you can give me some comments.

thank you

Thanks for posting that waveform! Definitely looks clean to me.

The voltage spikes are, unfortunately, pretty normal while taking this kind of waveform from a running engine. You can apply an active filter in the Pico software to make them go away, if you want, but I don't believe that's the source of your trouble code.

I see that you've verified cam timing, but I'm still wondering about a possible cam/crank relationship issue. We don't get the 1.6L engine in the US, so you'll have to help me out a bit. :blush: Is this a straightforward timing belt setup? Or some kind of hybrid belt/chain like on the 1.8L?

Unfortunately, even if you got a cam/crank waveform, I don't have access to any known good examples. Perhaps another member around here could help out on that. Does the engine run poorly? If so, I'd be interested to know what a vacuum gauge on the intake would say.

tommy wolf from positive lead diagnostics on youtube. (one of pauls friends) is the vw man. seems like cam crank is commmon on his channel..

hi,Tyler,thanks for sharing your thoughts.
this 1.6L engine is a very straight forward timing belt setup,no what we called "variable valve mechanism".
from your experiences i can conclude that this cam signal is totally fine and i have no point keep focusing on this issue.
and you suspect this could probably the valve timing issue still,so i will try to open up the cover and check again.

let me share some history of this car,
when the car came in with the MIL on,i check the cam sensor and i found out the sensor connector was crushed,and the previous workshop connected the sensor wire wrongly.
i have corrected the wire according to wiring diagram,and recheck again.
as i said,5V is good,groung is good,signal is also good.
so i thought the ECU is still in good shape, am i correct?

the engine runs quite well to me,but if i look at it closely during idling,i can see a very slight jerk,very light,but i am not sure if this is a symptom.

and Tyler,u mean u want me to measure the vacuum pressure at the intake side?

Thanks Tommy Wolf,do you have known good cam/crank waveform for this type of engine?

thank you

guys,problem is found.

the sprocket lock key was found worn out severely.(luckily it's still there,otherwise he will need an engine)

and the sprocket as well.

the camshaft looks like worn out as well.

i believe this happened due to a human installation error.(do you agree? coz the belt looks new)

they installed it according to the pulley sprocket marking,but the camshaft position was out.

that's why i thought the timing was good during the first check,i misjudged it. (my mistake)

until i got the verification by you all about the cam waveform,gave me confidence to move to another step.

thanks again,guys.

Holy CRAP. :woohoo: Stick a fork in that keyway, 'cause it's done! Nice job catching that one.

i believe this happened due to a human installation error.(do you agree? coz the belt looks new)

Possibly? I guess it would depend on if the camshaft sprocket was removed during the last belt service. Any issue with bolt tightness prior to removing the sprocket? Between this and the smashed CMP sensor, it sure seems like someone was having a rough time. :lol:

the engine runs quite well to me,but if i look at it closely during idling,i can see a very slight jerk,very light,but i am not sure if this is a symptom.

and Tyler,u mean u want me to measure the vacuum pressure at the intake side?

Yeah, I was thinking of a vacuum gauge on the brake booster port, or similar source of manifold vacuum. It's not a conclusive test, but typically engines with timing issues show significantly less than normal vacuum at idle. Something like 19" inHg would be good, while a reading of 15 inHg would be a red flag.

There was a great example of this in a recent thread. The Aveo started out at 14", found the timing belt off one tooth, and came back to 18" afterwards.

scannerdanner.com/forum/post-your-repair...um.html?limitstart=0

I'm not sure if the cam timing was off far enough in your case to show up on a vacuum gauge? Heck, given how loose that keyway was, the sprocket could have been shifting back and forth on the cam as the engine ran. :lol:

"Yeah, I was thinking of a vacuum gauge on the brake booster port, or similar source of manifold vacuum. It's not a conclusive test, but typically engines with timing issues show significantly less than normal vacuum at idle. Something like 19" inHg would be good, while a reading of 15 inHg would be a red flag.

There was a great example of this in a recent thread. The Aveo started out at 14", found the timing belt off one tooth, and came back to 18" afterwards.

scannerdanner.com/forum/post-your-repair...um.html?limitstart=0

I'm not sure if the cam timing was off far enough in your case to show up on a vacuum gauge? Heck, given how loose that keyway was, the sprocket could have been shifting back and forth on the cam as the engine ran. :lol:"

cool,Tyler,now i got your point,totally agree with this test,will definitely try this test if a similar case here again.
i will remark your pressure measurement as further reference.

thanks again anyway.

very helpful.

(one more question,do we have a waveform library here where we can share our known good waveform,so that anyone can look at it whoever need it,like my case i will post my cam/crank waveform once its fixed since i couldnt find any here?)

No waveform archive, unfortunately. The amount of work involved to set up and maintain something like that is huge, and Paul/Onyx are having enough fun with the Premium switch as it is. :lol:

Please feel free to post your cam/crank waveform to this thread, so (hopefully) someone searching the forums later will see this thread and find it.

Understood,but anyway,i am still waiting for the parts here,and will try to capture the waveform once its fixed.
And post it here.

Thanks Tyler,see ya.