Help with Cam Position

[JHarris]

OK, need some help here. I am getting cam position codes on my 05 a4 1.8t. I have replaced the cam sensor multiple times, checked and double check the timing (also paid a local VW shop to check it). Timing is spot on. Car runs great and holds boost good, but falls flat on its face between 4-5,500k. Definitely timing related. I have access to VCDS and was wondering if I can log the channel to see if its the ecu that is the fault or something else.

I have replaced the following trying to figure this out (i have come to the conclusion that it has to be electrical because of the speed in which the problem occurs, it falls on its face for 2 seconds then you get full power again).

New cams (intake & exhaust)
New lifters
new cam chain
new cam chain tensioner (oem)
used cam chain tensioner (known good)
new cam sensor
new timing belt and tensioner
new fuel pump
new injectors

I have both the stock tune and 1+ tune installed and it does it with both of them.

Anybody have any advise?

Thanks

Jesse

[mdh]

Have you checked your cam chain tensioner sensor? Sounds possible that the motor could be asking for variable timing and isn't getting it due to the chain tensioner not functioning. Just a thought.

[JHarris]

Yes, I've replaced it 2 times, once new and once with a known good one

[storey618]

how does one get there 1.8 to rev to 500,000 rpms?

[JHarris]

how does one get there 1.8 to rev to 500,000 rpms?

That would be sweet. Mistype should have said 5.5k

[cmiguel32]

Have cam timing issues too, but probably not the same kind.
My next step is replacing the Crank Position Sensor or Engine Speed sensor.

[storey618]

i was told by a local vag mechanic that he has never had to replace a cam sensor because they just dont normally go bad. when i had a cam code pop up it was a boost leak. how do you know its holding boost, do you have a gauge?

[JHarris]

Yes have boost gauge

[AudiA4_20T]

sounds like the keyway on either the cam or crank may have sheared but is jammed in place. The marks would lead you to believe that you're spot on but the actual timing is not

[BARRY]

when the chain tensioner is going out, you'll receive timing errors.

P1340 - Camshaft Position Sensor (G40) / Engine Speed Sensor (G28) Incor. Correlation - 002 Lower Limit Exceeded - Intermittent
P0012 - Bank 1 Camshaft A (Intake): Advance Setpoint not Reached (Over-Retarded) - 001 Upper Limit Exceeded

These two generally appear together. If they do your chain tensioner is dead, or on its way out. Almost never does the actual camshaft timing sensor go out. If your tensioner is bad you will have a loss of power. Also check your cam timing. If you're off by one tooth you'll have a loss of power. You'll need to remove your upper and middle timing belt cover to see the TDC alignment mark on the lower cover. You will also not see a trouble code for timing off by one tooth.

we'll need to see any logged faults to determine what is the issue. If it was a boost leak, your ECU may not give you a trouble code. mine didn't, but you'll have a loss of power.

[JHarris]

I'll go grab codes in a min

[old guy]

I'll go grab codes in a min

While you are at it monitor measuring block 90 position three or block 91 position four to read the actual cam position. Take a spin around the block and watch the readings. Under mild acceleration around 2,000 rpm you should see the cam advance go to +22° and around 4,000 rpm it should drop back to 0° advance. I took a spin around the block last week to confirm the readings for Cmiguel32. My readings ranged from -1° retard to +23° advance depending upon engine load and RPM.

Edit: And most definately take a close look at your keyways as Clint has suggested.

[JHarris]

https://youtu.be/v2Kq28W6u4w

Here is video. This is on stock tune. When it's done raining here I'll take it around block and check those blocks

[JHarris]

P0340 code, didn't get to vcds car tonight as I did not stop raining

[JHarris]

Code is 17748

I check measuring blocks, range from +22 to -1

Is there anyway to test the speed sensor?

[diagnosticator]

The cam position DTC is specifically regarding the timing relationship between the cam position sensor and the crank position sensor. If after changing everything you mentioned, that really only leaves the timing belt drive sprocket position on the crankshaft as the most likely cause of the DTC stored. It does not take much error to set the DTC. The only item left is the crank timing belt drive sprocket position on the crankshaft as Clint and others have suggested.