06 jetta 5 speed stalls intermittently

Our 06 jetta 5 speed will randomly lose power while driving. The engine and electrical functions are on but there is no throttle response. We step the clutch in and shift gears and it will take right off. May happen several times a day and then not again for a week, although its getting more frequent. Scanner codes include cam position sensor fault, and variable turbo position fault. Mechanic isn’t sure either of these are related to the stalling problem. Anyone know what we should try first. Car has 302k and runs great otherwise.

These problems are common on our cars and it's usually a chaffed harness or dirty grounds. Try pulling the battery and airbox and inspect the engine harnesses and inspect the wires. Chaffing is very common at the harness around the starter and other points where the harness is held down. While you're down there, clean the ground connections.

I took your advice and searched for chaffed wires but really found nothing that looked bad at all. Also cleaned grounds, which also seemed clean but now are shiny. Test drove the car and it still stalls randomly just like before. Any chance this is a fuel system problem? I thought the car had reacted to gear change before and took off, but if I change gears fast enough its still dead. And if I do nothing but coast and hold the pedal down it eventually takes off. Plan to change fuel filter tomorrow since its a simple fix. I doubt it will solve the problem as clogged filters usually don’t act like this.

When was the last time the fuel filter was changed? Also, check the in-tank fuel pump for flow.

I just ran into this thread that goes along with what ala8888 said.

http://forums.tdiclub.com/showthread.php?t=484015

Post #14

That's a good suggestion, so far you're taking the proper diagnostic route, starting with the simple and cheapest things first. Do you have access to VCDS? VCDS will give you a lot more detail than a normal code reader.

Cam position sensor failures are rare on these engines, but do occur. Usually it's a wiring issue that's the cause of a CPS fault. The wires for the CPS and VNT control do run near each other. Here's a detailed thread about the CPS.

http://forums.tdiclub.com/showthread.php?t=389318

Keep in mind that the engine can run without the cam position sensor, when that happened to me the ECU ended up using the crank position sensor and the tach would no longer read.

I'm confused on what your problem is. You said in the title that it stalls but in your post, you said it looses power.

Does the engine die completely, or does it stay running with low power?

The engine basically has no throttle response for 5-7 seconds, then comes back and runs fine. Might happen a few to several times in a few miles driving and then be fine for the next 20 miles...
Its getting steadily more frequent. A month ago it happened only five or so times every 500 miles. Now its at least ten times in 50 miles.
Codes are both intermittent, cps sensor and turbo actuator position sensor

I had been thinking lift pump failure or fault in wiring to lift pump but the car never sputters or lacks power like a fuel supply problem. It is either running great or completely flat on throttle response for 5-7 seconds. I purposely drove some big hills last night which it roaredup with no problem, then went a few miles more and started cutting out again.

Yep. Sounds like a wiring issue.

If it is happening that frequently, you should be able to catch some data with a scan tool. Could be something as simple as a brake light switch coming active when it shouldn't (like you were driving two-footed). If the ECU sees brake pedal switch signal, the RPMs go to idle or just above idle, regardless of how far down you push the accelerator pedal.

Bad VNT look into Zip Tie mod easy and cheap to try. Not say that is what it is but sounds like it could be. VCDS is really needed for these cars.

Will the brake light switch act this way on a five speed manual? I see that with an auto trans but not so much a manual. Will check it later this week. Going to be too busy to work on it for a couple days.

ECU uses brake switch input no matter which transmission it has. Manuals also use the clutch pedal input (there is an upper and a lower).