Touareg TDI intermittently stalling at traffic lights when at idle. - Club Touareg Forums
 
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post #1 of 10 Old 10-15-2018 Thread Starter
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Touareg TDI intermittently stalling at traffic lights when at idle.




Hi everyone, after a long period of smooth sailing, the treg has developed an intermittent fault, hoping for any insights you may have.

Problem statement:



3.0tdi (my08 model: BKS) infrequently stalls when stopped at traffic lights.

frequency is approx weekly, no pattern identifiable.

no warning / CEL indicator is given

has occurred with diesel fuel level below 25%, refilled and now occurred when fuel level is above 75%.

car has been (self) serviced every 10000km, I have owned since 130000k, currently nearly due for 170000k service.

car is at running temp when issue occurs, however has only run for 20 minutes or less. (Strangely it has happened all 3 times on the same road, very close to the same part of my journey. I am sure that this is only a coincidence, however it is a 20km journey it has happened within 1km of the same place each time)





after stall incident when I shift to park and attempt to restart the car will hesitate and not start for a few seconds, somehow feels like fuel not present / or start is inhibited from firing up.


once key is removed and after 10- 30 seconds has elapsed the car then starts as per usual (2 or 3 cranks) and issue not seen again for some period.

has occurred 4 times over last month or so, it appears to be increasing in frequency.



No DTC or alarm code is thrown or stored when VCD scan performed.



So far, aside from scanning the car after 2 separate occurrences the only troubleshooting I have performed is (wishfully) checking the fuses are all working and in place correctly, no fault found with fuses.



Reading through CT and some other TDI Forums has given me several avenues to investigate,

  • one common fault on the Audi forums appears to be a failure at a fuel pump relay,
  • fuel pump issue
  • crank angle sensor not giving a reliable signal the ECU
  • egr fault? seems unlikely without a CEL or similar


Regards
Sydneytreg


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post #2 of 10 Old 10-15-2018
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I'm sorry I cannot help but your post is one the best I've seen explaining a problem in great detail and the thought process in trying to identify any consistencies and the possible issues.

I only wish others who ask for help would give half as much info rather than "My car won't start - what's my problem? "!!

So I hope more technically minded members on here will be able to help you get to the bottom of the problem so you can soon resolve it.

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post #3 of 10 Old 10-15-2018 Thread Starter
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Thanks Nooby!


I was conscious of the old "it wont go" post, it took a few attempts to get it all down on paper and readable.


I always got told that a problem well stated is a problem half solved...


Seems like I did the easy part! fingers crossed.
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post #4 of 10 Old 10-15-2018 Thread Starter
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thinking a little more,

I believe the micro switch in the drivers door handle is defective, I don't get a "door open" signal when drivers door (RHS) is opened, this likely prevents the in tank pump(s) from activating when the door is opened prior to startup, However the always car starts fine and the issue of the RHS drivers door not indicating open status came with the car 4 years ago!

Unrelated,

Does the 3.0 TDI BKS fuel system have two pumps in the tank (as documented in SSP 351 ), and if so, do they act in parallel? Are there any filters that I can get at, and hence clean or replace?
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post #5 of 10 Old 10-16-2018 Thread Starter
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Hall sender

I contacted to one of the "recommended" mechanics from the forum about the issue and he suggested swapping out the Cam angle sensor then the crank angle sensor in that order only due to ease of install and the time taken). I was leaning towards fuel side problems in my line of thought, however he was super helpful, explaining his reasoning and logic, so i will try this as a first course of action.

Before I call VW and go so shopping, Are sensor G40 and sensor G28 the Cam and Crank position sensors respectively, they are described as Engine speed sensor and Hall Sender in SSP 351? Does anyone have any tips on swapping either of the sensors out, the mechanic indicated the cam sensor was a pretty easy job ,less so for the Crank sensor.




Regards
Wayne
Attached Files
File Type: pdf SSP_351 Common rail fuel injection system fitted in the 3.0l V6 TDI engine.pdf (891.7 KB, 13 views)
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post #6 of 10 Old 11-03-2018 Thread Starter
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fingers crossed; final update

After some helpful correspondence with a very helpful and knowledgeable forum member and the assistance of this post: https://www.clubtouareg.com/forums/f...22-150010.html I have (located) and replaced the engine speed sensor G28 (070957147 VW part number, 0261210261 Bosch part number). Prior to the sensor being swapped out the car would not even idle long enough to run the full VCDS scan, so the problem was progressing in frequency and severity, no code was thrown throughout the entire period.

The Treg seems to run smoothly now, no issues stalling at idle anymore.

As the referenced post mentions, its a job you can perform at home and as with all sensor swap outs, being double jointed and having hand the size if a small child would be very beneficial, locating the sensor is all part of the fun, its on LHS, down low. Getting the wheels turned all the way to the right allowed far better access - the photo in the post was invaluable, getting the wiring connector apart is a little difficult, I didn't have a hoist handy,which would make the entire process a little simpler,

A second attempt would not be as hard as i made it look the first time!

Case closed? .... fingers crossed.


Sydneytreg
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post #7 of 10 Old 11-04-2018
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Good to see you fixed it.
Mine (V6 3.2) stalled in traffic light a while back. BUT I got a speed sensor g28 error when I scanned. Treg started after a few minutes on the side of the road. I Replaced the sensor later on and Treg has never stalled since. Prior to this issue it has never showed any starting issues. This happened after I've been pushing it a bit hard and then came to a stop. Treg was 128000 km old.
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post #8 of 10 Old 11-04-2018
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Quote:
Originally Posted by sydneytreg View Post
After some helpful correspondence with a very helpful and knowledgeable forum member and the assistance of this post: https://www.clubtouareg.com/forums/f...22-150010.html I have (located) and replaced the engine speed sensor G28 (070957147 VW part number, 0261210261 Bosch part number). Prior to the sensor being swapped out the car would not even idle long enough to run the full VCDS scan, so the problem was progressing in frequency and severity, no code was thrown throughout the entire period.

The Treg seems to run smoothly now, no issues stalling at idle anymore.

As the referenced post mentions, its a job you can perform at home and as with all sensor swap outs, being double jointed and having hand the size if a small child would be very beneficial, locating the sensor is all part of the fun, its on LHS, down low. Getting the wheels turned all the way to the right allowed far better access - the photo in the post was invaluable, getting the wiring connector apart is a little difficult, I didn't have a hoist handy,which would make the entire process a little simpler,

A second attempt would not be as hard as i made it look the first time!

Case closed? .... fingers crossed.





Sydneytreg





Well done


regards
Drag
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post #9 of 10 Old 11-06-2018 Thread Starter
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consumption at idle...

As a further curiosity, I have always driven around with the mfd displaying instant fuel consumption, the consumption at idle always flicked between 0.7 and 0.8 l/h and over the last 6 - 9 months has slowly increased to 1.1 l/h. at steady idle, (AC and lights switched off) and during occasional periods of mystery rough idle at traffic lights a it reports 1.3 + l/h.

swapping out the engine speed sensor appears to have fixed the rough idle, and the fuel consumption is now rock solid at 0.7 l/h under the same idle condition.

She has been trying to tell me she has had a dicky sensor for some time, I just wasn't listening

I now understand that the position value being reported by this sensor is interlocked with firing times and flow rates through the injectors and logically, it seems like the ECU can tolerate some degree of out of range / invalid value from this sensor and compensates by being overly generous with the fuel delivery, but when the sensor reports too far out of range the ECU inhibits injectors to prevent the car from starting? (all speculation) however all of this happened without any alarm being reported or visible when scanned which is what I find so interesting.



For a car that was born to report error codes why did none of this trip any alarms?
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post #10 of 10 Old 11-06-2018
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Mine didn't even show any sign. But when it stalled it logged speed sensor error.


Sent from my iPhone using Tapatalk
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