Ranier

2000 Passat 1.8turbo ATW 5speed (100k miles used car) If you think you can help diagnose the problem, I would really appreciate the feedback. I purchased the car recently and I'm not sure about previous owners' maintenance record and carfax didn't produce much. No problems at first and I was really pleased with the car, then it went downhill fast.

First I noticed the car would not accelerate normally from 0 to 2,500 rpm. It felt like it was "missing", would not accelerate fast but would slowly build up speed and then at 2,800 rpm acceleration would kick in and act normal. The other symptom is I noticed it was having trouble starting. It went from starting fine to me having to tap the gas a tiny bit. Then the very next day it wouldn't start. Scanned it and the DTC that came up was PO341. At this point the following work was done. The cam pos. sensor was replaced as well as spark plugs, timing belt, water pump, valve cover gaskets, oil and antifreeze. I got the timing belt kit from ECS tuning and it came with everything needed. After the work was done, the car started up great, I cleared the engine codes and it accelerated fine. It seemed like the problem was fixed until the engine light came on. The very next day I noticed it had problems starting and the same symptoms as before were coming back. Scanned the DTC's and got the following.

16725 (PO341 Camshaft Pos.Sensor Circ. Range/Performance)
17521 (P1113 Bank1, sensor 1, Internal resistance too large)

A mechanic from an Audi and VW shop (independent shop) said that if the Cam Sensor has been replaced and it the T-belt kit is new, the problem is likely the Cam Chain Tensioner. He said if the cam chain tensioner is off than the timing will be off enough to not get good compression and not accelerate well (explaining the symptoms). He said it is something he has seen often. ON THE OTHER HAND, talking with other VW mechanics they said the cam chain tensioner rarely fails.

I realize the O2 sensor is an entirely different problem from the ignition system problem. I don't want to tear everything apart fixing stuff that isn't at the root of the problem. I would really appreciate any suggestions on the ignition problem and the cam sensor error. I don't know why I am getting the same cam sensor error after replacing it and all the other work that was done???

DaveInSaltLake

off by one tooth between the intake and exhaust cams. whoever had it apart last botched the job and it was a bit of a process to diagnose. I hope you kept your old CPS so you can swap it back and forth with the 'new' one as you troubleshoot.

If you have a Bentley you can pull your valve cover and count chain links between the cams.

Monkeyboy

I would verify timing. Belt timing and cam chain tensioner. Open her up and verify both at the same time. Tensioner plastic rails may be f'ed up as well....this can be looked at while the valve cover is off. Cam position sensor rarely fails....this is the Hall sensor at the front of the engine.

Who did the timing belt?

Cam chain tensioner rarely fails!!??!! Right...let me show you some pictures! Maybe the pre2001 models rarely fail, but I have seen lots of posts of failed cam tensioner rails.

I recently had mine checked like this (belt and cam chain), cost @$450 at an indy shop - they found belt timing was off @2 teeth (a different shop was the last one that would have affected belt timing). To me, cheap for peace of mind that timing is OK now.



16725/P0341/000833 - Camshaft Position Sensor (G40): Implausible Signal
Possible Symptoms
Malfunction Indicator Light (MIL) active
Possible Causes
Wiring from/to Camshaft Position Sensor (G40) faulty
Camshaft Position Sensor (G40) faulty
Timing misaligned
Possible Solutions
Check Wiring from/to Camshaft Position Sensor (G40)
Check Camshaft Position Sensor (G40)
Check Timing

Ranier

Been out of town and just got back. Thanks for your feedback. If you do have pics of a failed chain tensioner post them, i'll try to get the timing checked for free by the shop that did the belt and water pump and hall sender.

Thanks for responding, I posted the same question on the bentley forum but nobody responded yet.

Ranier

Thanks for the feedback. I've been out of town so no time to tinker with my car. I'll check the timing first and post my progress if it's off. I emailed the shop who did the timing belt and water pump and asked them to double check the job for free.

Again thanks, nobody responded to my same post on the bentley forum so i'm glad to hear back.

Monkeyboy

<center><img src="http://pictureposter.audiworld.com/433/bottom.jpg"></center><p>Bottom of cam adjuster unit. The plastic rail was broken into pieces, a big metal gouge and lots of pieces that should not be missing.
Had to drop oil pan, clean everything out, replace oil pickup tube, replace cam adjust...been fine since (@2 years now) - could have been disasterous

DaveInSaltLake

<img src="http://i47.photobucket.com/albums/f174/DavesData2/Thomas%20A4/CamChainTensioner.jpg" border="0" alt="Photobucket">

Ranier

Mine is a belt and not a chain, do you know if the tensioner would look the same. I looked at them on ECStunning.com and got a feal for price and some tensioners can be crazy expensive.

Ranier

Thanks for the pic, mine is a belt not a chain though, I think these parts can cost a ton. I will get in there early next week and check things out.

DaveInSaltLake

the camshafts in each head. It's a short chain between the exhaust cam and intake cam that you can see when you remove the valve cover.

The timing belt is a different beast all together.