T6 not firing on cylinder four

[Ebsj1600]

Hello, so i have been reading all the posts in here that i feel are relevant to my case but it seems like i am chasing something i really cant figure out myself. so here is the story,

i bought a 2016 t6 150hp with the cxfa engine. 226' km on the counter and it was rigged just as i wanted it with mat foil all over and big rims. knew i just had to have the car.... not so sure now, bought it in Ocotober and it is still in the garage. when i was looking at the car i first reacted to a loud metallic noise but dit not think of it as something catastrophic and checked all the live data that i could regarding the hpfp with vcds and thought it had to be something else.

first problem i had with the car a cupel of weeks after buying it was i stopped under load, fuel pressure to high i got, (this was after remapping the car and under test drive) when it stopped i had problems to start it up again and when i got it running it was shaking and not feeling well and i thought i had wrecked the engine but when i talked with the garage that did the tune they where convinced that it was injector fault at cylinder 4 this based on temperature readings and internal moment which stated 420nm at all except number 4 that one had -150nm. so i took the car home changed the injector coded it in successfully and startet the car again and same result -150nm at 4. so next thing up was to check compression and to my surprise it was good or at least almost even.

after that i changed glow plugs while i was at it, and changed injector positions around started up the car and now it was all good all internal moment readings was about 450-420nm and the car was good to go. and i was left with the feeling that how did i fix that without fixing anything... but i started having startup problems after this.. no problem to start in -12 degrees but if the car was warm or had been part with nose down i could not get it to start, sometimes it would help to run the fuel pump with vcds but sometimes not. the car also reported a consumption to 10L\100km but in reality it was much more about 13-15l\100km (ish) so then i thought it had to be with the low pressure side of fuel or the return or that it did not hold pressure in the common rail. I change the n276 valve and checked the n290(ohm measured to same value as one in a fellow worker's car. 5,8ohm) also checked the return amount on the injectors and they where even and not excessive. after this i started the car in hopes that the no start problem would be gone but in stead i was back to start with the negative internal moment. so since i haven't had the injectors out this time i thought it had to be wiring since that was the only part i had touch this time checked the wirings down to the ecu and to the connector of injector 1 and 4 just for reference but no deviation there. last ting i did now was to change the ecm, cloned the old one and installed one from a collided car, same numbers and everything. hoping that it would be a injector channel in the ecu that would be the culprit but no.. still negative moment on cylinder four..


i have done some checks with vcds along this journey but i am just a hobby enthusiast trying to fix a car so i am not any expert in the world of vcds or so, so if anyone have any idea where i should start next please do comment. btw the timing belt was done in 2025 or late 2024 i cant exactly remember now but it has been changed by a workshop.

both of these photos are after all the above and last picture is at idel, i forgot to have the RPM ticked off.





i am grateful for all the help i can get and if i should supply any other scan please let me know.


-Esben

 

[DaveD]

Hello, so i have been reading all the posts in here that i feel are relevant to my case but it seems like i am chasing something i really cant figure out myself. so here is the story,

i bought a 2016 t6 150hp with the cxfa engine. 226' km on the counter and it was rigged just as i wanted it with mat foil all over and big rims. knew i just had to have the car.... not so sure now, bought it in Ocotober and it is still in the garage. when i was looking at the car i first reacted to a loud metallic noise but dit not think of it as something catastrophic and checked all the live data that i could regarding the hpfp with vcds and thought it had to be something else.

first problem i had with the car a cupel of weeks after buying it was i stopped under load, fuel pressure to high i got, (this was after remapping the car and under test drive) when it stopped i had problems to start it up again and when i got it running it was shaking and not feeling well and i thought i had wrecked the engine but when i talked with the garage that did the tune they where convinced that it was injector fault at cylinder 4 this based on temperature readings and internal moment which stated 420nm at all except number 4 that one had -150nm. so i took the car home changed the injector coded it in successfully and startet the car again and same result -150nm at 4. so next thing up was to check compression and to my surprise it was good or at least almost even.

after that i changed glow plugs while i was at it, and changed injector positions around started up the car and now it was all good all internal moment readings was about 450-420nm and the car was good to go. and i was left with the feeling that how did i fix that without fixing anything... but i started having startup problems after this.. no problem to start in -12 degrees but if the car was warm or had been part with nose down i could not get it to start, sometimes it would help to run the fuel pump with vcds but sometimes not. the car also reported a consumption to 10L\100km but in reality it was much more about 13-15l\100km (ish) so then i thought it had to be with the low pressure side of fuel or the return or that it did not hold pressure in the common rail. I change the n276 valve and checked the n290(ohm measured to same value as one in a fellow worker's car. 5,8ohm) also checked the return amount on the injectors and they where even and not excessive. after this i started the car in hopes that the no start problem would be gone but in stead i was back to start with the negative internal moment. so since i haven't had the injectors out this time i thought it had to be wiring since that was the only part i had touch this time checked the wirings down to the ecu and to the connector of injector 1 and 4 just for reference but no deviation there. last ting i did now was to change the ecm, cloned the old one and installed one from a collided car, same numbers and everything. hoping that it would be a injector channel in the ecu that would be the culprit but no.. still negative moment on cylinder four..


i have done some checks with vcds along this journey but i am just a hobby enthusiast trying to fix a car so i am not any expert in the world of vcds or so, so if anyone have any idea where i should start next please do comment. btw the timing belt was done in 2025 or late 2024 i cant exactly remember now but it has been changed by a workshop.

both of these photos are after all the above and last picture is at idel, i forgot to have the RPM ticked off.

View attachment 315378View attachment 315379View attachment 315380



i am grateful for all the help i can get and if i should supply any other scan please let me know.


-Esben

Welcome to the Forum.
To be clear, you say you had the van remapped and then the problems started?
Is it possible to have the remap removed, i.e return it to the VW factory map, to see if the map has created the problem?
I don't know consumer law in Norway, but I'd assume that you have invalidated any warranty you might have had by remapping it.

 

[Ebsj1600]

Welcome to the Forum.
To be clear, you say you had the van remapped and then the problems started?
Is it possible to have the remap removed, i.e return it to the VW factory map, to see if the map has created the problem?
I don't know consumer law in Norway, but I'd assume that you have invalidated any warranty you might have had by remapping it.

Hello and thanks, no warranty on a ten year old car anyway so nothing to worry about there, and yes i have been talking to they guys doing the tuning and they are trying to help me as much as possible but they stat that it probable isnet related to software as the fault is not always there. if it would have been the tune it should ether be there constantly or not, i dont know but now i have two ecu's so no problem take one of them over there and try

 

[mmi]

Please post the following

1) Full VCDS Auto-Scan
2) Engine blockmap - Ignition ON/engine OFF
3) Engine blockmap - Engine running at idle


How-to create a blockmap file:

[VCDS]
[Applications]
[Controller Channel Map]
- Single Controller Address = 01
- Login or security access code: Leave blank
- Function: Measuring values
- Output: CSV file
[Go]

The result (TXT and CSV) files are saved into directory C:\Ross-Tech\VCDS\Logs
Please attach the files here.

 

[Ebsj1600]

Hello, and after a long period of snow and hat I have finally picked up the ecu that is not mapped, tried starting the car here the other day before swapping it, no start condition, just regular cranking that goes over to the sound of no resistance whilst cranking. Swaps the ecu and it fires right up and it has internal moment on all four cylinders. I was happy but not convinced as the no start usually happens after the engine is up to temperature and on its way cooling down again, so I figure let’s keep it running on idle while I eat my dinner and then stop it let it sit and try start it again… only problem after half an hour is that when I go out to the car again it is diesel all over the place like probably 10l on the ground… turns out that the return line on injector 1 has exploded… so first thing I tried now while I’m waiting for a new harness for the return is to test the rest of the return system… is is kind of restricted.. is it supposed to be that? I used a manual pump and could easily pump 1 bar of pressure into it and it would slowly come down.. but to me that seems wrong, especially since the returns from the injection share the same line, no wonder I have insane fuel consumption and a loud injector noise I can not locate?

Anyways what components are there in the return line from the engine and to the tank? Is there any on way valve or any other thing I should check ?

And yes I will upload the files you requested when I can start the car again Mmi thanks for the help so far people

 

[manfrotto]

Fuel syetem overview from the manual...

 

[Ebsj1600]

okay, so since the return from the cr and injectors goes T’s in to the supply line my theory of a blocked return line is dead

 

[manfrotto]

okay, so since the return from the cr and injectors goes T’s in to the supply line my theory of a blocked return line is dead

I have seen a few variations on the fuel filter, and the return pipe may go into the filter in some cases - you can tell by the number of connections on the filter.
There may also be some pressure back through the lift pump.

 

[Ebsj1600]

Yeah, my car is just as the diagram you posted, two connections on the filter with the return line coming form cr and injectors connecting in to the supply line right before the VF marked connector on the fuel filter.

 

[Ebsj1600]

okay.! so got the fuel line replaced with an OEM VW and now the car is running and it is actual starting every time and it has even numbers on internal moment. so that's good, only thing now is that the ecu that is in the car now throws me the 27089 Engine control module incorrectly coded. when i check the ecu under 02 engine i can see that the current coding is just zeroes, when i try to log in with security access and then try to past the code which was original in the ecu it just states coding rejected error 31: request out of range.. this is new to me and i dont even know if it is the right thing i am trying i talked with the tuner guy who cleaned the ecu for me and they said that was the way to do it.

picture is from active session with vcds and .txt fil is from an old autoscan where i took the coding from. I've also tried manually punching in the number via long coding, but same result.



to do it. any tips ?

 

[mmi]

Engine off?

 

[Ebsj1600]

yes