BEW stalling on idle or low rpm

EDIT. FIXED THE PROBLEM. IT WAS THE CRANK SENSOR.
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(specifically the wires leading into it.)
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Just for reference this is a 2005 mk4 bew tdi wagon 5sp auto GLS.

For the past few months ive been waiting for my car to throw a code with no luck.
Its to the point were if i leave it at idle its bound to stall. Especially if it is hot.
Typically it will surge a couple times before it actually stalls. Its kind of scary when im taking a left turn and all of a sudden have no power steering.

(one thing to note is that i tested my mpg recently and it was 35mpg at 90% freeway this is the lowest ive ever had in a tdi)

I have not done too much to test it. I am mainly starting this thread because out of the 10 or so threads i read about this same problem. Nobody posted a solution.

I had 2 ideas of what it could be and now after reading those threads i have 3.

First is easy. I had a bad crank position sensor before and i replaced it with one out of my friends bew that just so happened to get totaled within a couple days of mine going out.
The thing is, the one i replaced it with never had any problems and when mine was going out it threw a code every time it would stall.
I think that might be where i start.

The second possibility is the flap in the egr. One of the times it stalled I opened my hood and could hear something making a noise that sounded like a small motor glitching. could not tell exactly where it was coming from but it sounded like the egr. This is while the engine was not running but the key was in the on position.
My idea on this is that the flap inside is either getting stuck or just running haywire. If it closes it seems like it could cause a stall without throwing a code.

Now the third possibility is the fuel. It seems like more people suggest that it is the lift pump. the electric one in the tank. Apparently it will even run when the pump is not working as long as there is no air in the line. The first euro models didn't even have the pump.
But it will occasionally stall.
Also i haven't replaced the fuel filter. But i should either way.

Other than that i haven't noticed anything that would cause it to stall. Its been happening for over 6 months now.

I can hear the lift pump turn on for 2 seconds every time i turn the key to the on position.

So if anybody has any ideas on what it could be or thoughts on the noise i get that sounds like the egr. or why im only getting 35mpg that would be super helpful.

Hopefully i can post a solution this time.

Lift pump, tandem pump, shutdown valve (shut down flap), check those. Check the flow of the lift pump, the pressure on tandem pump, and check how the flap is working.

My faulty crank sensor did not trigger a DTC, but the attached cable had become fragile over the years. I found this out by wiggling this cable to get the car started. It still stalled occasionally which, as you know, is scary.

i was going to throw in, when i was troubleshooting my bew for a fuel issue that turned out to be a bad tandem pump it never stalled ever but had no power and would not rev. however in the trouble shooting process i removed the crank sensor to check and clean it and reinstalled it.
i did not tighten it down well because i did not have the socket on hand to fit the 12 point when i went to reinstall it so i put it in finger tight to come back to it and forgot for a bit.

it began stalling at idle and takeoffs from stop after i fixed the tandem pump and it took me about 3 days to remember that i had not tightened down the ckp sensor.

reached in and did that no stalls since. so bad wiring or loose or dirty could probably do the same thing. weird thing was it ran fine under load or moving it was just at idle or take off.

hope that helps.

i just removed a tandem pump that was shot and car would not rev over 3800 in neutral and had zilch for power but it never stalled till i screwed with the ckp sensor.

dont know if injector harness plug being loose cold cause that as an alternate thought mine has never given me problems but i did find it loose on one of my cars and tightened it..w.as asymptomatic though

So i havent had much time to mess with it. But i was able to run diagnostic in vag com.
It had an intermittent code for the cam sensor. But that could probably be from stalling out so many times.

When i turn the key on without starting it i can hear the fuel pump for a couple seconds every time.

I did get a fuel filter i am going to install as well.

I think the first think i will do is just replace the cam sensor with a new one.
I know when I tested my old one it would show the proper resistance. I had to test about 10 times before it had the wrong reading.

I really dont want it to be the cam sensor.

I am still concerned about the flap in the egr. That is easier to remove than i thought so i will probably clean it at least.

I think i am going to give a week or so or at least wait for it to stall after everything i do just so i know what it was.

#1 crank sensor, read they don't give a code or sometimes shows up as a cam sensor code, odd. Always check wiring/connects.
#2 I recently read of a BEW where the EGR motor failed, these will generally throw an EGR code.
#3 Many post dead in tank pumps, some tandem pump failures. Just from reading here, it seems like the in tank pump fails but car continues to run O.K., seems like that would stress the tandem pump.
All these things can be tested.
VW TDI Search Engine

BobnOH said:

#1 crank sensor, read they don't give a code or sometimes shows up as a cam sensor code, odd. Always check wiring/connects.
#2 I recently read of a BEW where the EGR motor failed, these will generally throw an EGR code.
#3 Many post dead in tank pumps, some tandem pump failures. Just from reading here, it seems like the in tank pump fails but car continues to run O.K., seems like that would stress the tandem pump.
All these things can be tested.
VW TDI Search Engine

Click to expand...

I do know how to test the crank sensor. The problem is that if it is intermittent then if it the resistance is low or 0 the car dies. And then it will read just fine. Last time one went out on me it had similar symptoms but eventually it threw a code.

I think your right about the egr throwing a code.

The pump will be the last thing just because i can hear it and i can see it pumping through the clear lines.

Remove your timing belt cover and carefully inspect the entire length of the belt.

When my timing belt lost a bunch of teeth, I got a cam position sensor code.

It ran worse and worse until timing moved enough that it wouldn't run.

Hope that isn't your problem, but if it is, and you catch it before timing is way off, maybe a new belt is all you'll need instead of new everything.

Mike_04GolfTDI said:

Remove your timing belt cover and carefully inspect the entire length of the belt.

When my timing belt lost a bunch of teeth, I got a cam position sensor code.

It ran worse and worse until timing moved enough that it wouldn't run.

Hope that isn't your problem, but if it is, and you catch it before timing is way off, maybe a new belt is all you'll need instead of new everything.

Click to expand...

Oh yah. That would literally be the worst.
I actually just changed my timing belt and my valves valve cover head gasket etc. etc. about 40-50k miles ago.

I was driving up the freeway and my timing belt slipped.

One regret is that i did not put a new cam in. It showed no signs of uneven wear.

I will check that out. I used a gates belt but its easy enough.

I have a cam sensor on the way. Im trying to everything one at a time so i know what the actual problem is once its fixed.

It died about 8 times in 20 min last night. Still no CEL.

One thing to add is i was burning some oil the other day. I had 4 people in my car and was driving up a pretty steep hill. When i got to the top we noticed smoke. It was coming from around the egr maybe on the back of the engine. I figured it was not a new leak just got much hotter than normal and burned a little random oil off. Ive yet to see an older diesel without oil on the backside of it.

she_loves_the_D said:

One thing to add is i was burning some oil the other day. I had 4 people in my car and was driving up a pretty steep hill. When i got to the top we noticed smoke. It was coming from around the egr maybe on the back of the engine. I figured it was not a new leak just got much hotter than normal and burned a little random oil off. Ive yet to see an older diesel without oil on the backside of it.

Click to expand...

When my timing belt slipped, after I limped the car (running poorly) to a place where I could park, I also had oily smoke coming from that same location.

In my case, I think that smoke was caused by a build up of oil residue which had leaked out where the ASV meets the intake manifold. My car has always leaked from that point, even when it was almost new and I hadn't ever taken it apart. (Recently I sealed it up with an automotive silicone that claims to have excellent oil resistance).

When the cam timing was way off, I think the exhaust manifold got really hot and burnt off that oil. I'm not exactly sure why that would be the case, but it did seem like that. You could tell it was way hotter than normal because of the burning oil, and also it was making kind of a ticking noise like you hear when a gasoline engine is cooling down.

So anyway, it's interesting that you have the oil smoke coming from about the same place where I did. It only takes a few minutes to check your belt and put your mind at ease. Hopefully it's not that.

So im a bit tarded.
I got my new crank sensor in and went to install it. When i removed the old one i noticed i ordered a cam sensor. I even looked up cam sensor lol. Got it for cheap at least.

The insulation around the wire coming out of the sensor is coming off a little. the wires look good but hopefully that is a sign that the cranck sensor is the actual problem. I have one on the way now.

Mike_04GolfTDI said:

When my timing belt slipped, after I limped the car (running poorly) to a place where I could park, I also had oily... It only takes a few minutes to check your belt and put your mind at ease. Hopefully it's not that.

Click to expand...

Yah ill check it out.
I think its actually leaking from the seal on the egr. I noticed that it was dripping or spreading to where the vacuum goes into the turbos actuator.

Everything is clean and inside the egr is fairly clean. I think it was just burning because the turbo got extra hot going up a steep hill with extra weight.

So it finally wouldn't start today. Luckily i got the crank sensor in last night.

i was able to get it started. Then pulled on the wire leading to the sensor and the car died. I was able to replicate it a couple times.
So that was definitely the problem.

Still no code. I tried to start it with the sensor disconnected and it did throw a code for engine speed something.

Now to replace the seal on the egr and apparently replace the drivers seat belt igniter.


Thanks for the help and suggestions.