VW T6 (2018 cxha) - mystery engine jerks and judders av 2-3k rpm problems

[mr.change84]

Hi T6 forum,

Hello from .

(New to this forum, but done countless hours of searching for simular problems.)

I'm calling out for some help/advice with our engine problem.

Long story short(ish)..

We bought a "project" car with broken timing belt (toothed belt).
Belt was split, but not broken off.
Engine could be turned on crank bolt.

Spec:
It's an 17/18 T6 L2, with CXHA 150 engine.
Fwd and manual g.box.
Engine at 190k, so it was soon due for a new timingbelt (210.000km).Car has a good service history (company car/one owner)

Got the car home and started looking at it.
After some research, we ended up pulling the injectors and took off the cam-cover.
After inspecting the camshaft modul, we found it was twisted.
But luckily noting else was damaged.
Not even the rollers were effected.

Fast forward, new camshaft-modul, timingbelt kit/waterpump, lots of new seals (injectors seal and bolt too) were fitted.

At this point we didn't have vcds, so we prefilled the fuelrail/hight pressure lines and manually got all of the air out the injectors by cranking on starter.

At first starting temp, it run for 10sec and stopped. But after some more attempts it fired up, but run on 2/3 cylinder.
We consulted with a tech friend, and he advised us to take it for a run (up hill) and push it past 3k rpm. And after 200m at 3k, engine came really alive.. all was good. Pulled really strong and sound so sweet.

After this we did more service with all fluids, filters etc (not fuelfilter at this point)..
We were really pleased with this project, and parked the car away for a while.
(This car is not our daily. It will be used for towing the racecar and other stuff.)

Now to present time and the problems..

Maby a months ago I started driving the car more.
After some use I started noticing the fan in front was blowing hard after I turned off the car.
(Now I know this was the DPF regen, but at that time I didn't think much of it.)
Unfortunately short trip's)

One evening I was driving the car back to storage, and on the highway cruising i 5th or 6th gear, when applying small throttle movment, I noticing the car started jerks and judders.
Most noticeable between 1800-2800ish rpm.
At 2k rpm it feels like "missfire" or small fuel cuts, or lack of boost from turbo and some small vibration from the engine. Hard to explain.
If I throttle hard and I go past 2800-3000rpm, I don't feel that jerks and judders.

went online and tried to troubleshoot some.
remember, no fault codes at this point.

All guided me towards dpf regeneration not completed or under process. Best Google advice was drive hard at 2500-3000 rpm on highway, for a longer time. So I did.. and nothing has changed.
At this point we thought it was stuck egr valve, and plan all along was erg delete and stage1/soft tune due to trailer towing.

So I called a nearby, well known Norwegian tuner and they helped me with this.
I told him about this "problem" and they scanned the car before session.
He said erg valve was 28% open at idle and was probably stuck open and the cause of this..

3 hours later, car was done, and I went to pick it up. The "tuner" had left (it was Friday at 1600) so I was only left with the key.
I was really excited to test the "new" car, and to see if the jerks and judders was gone.

BUT sadly no.. it was still there.. f@#k..

Same evening I went to a auto store and bought a MAF cleaner spray and went on testing that.
Car got worse ish, and on the way to work our 1. Fault code.. P0087.. my old code-reader said low fuel pressure. But I this this was from spraying the MAF.
Now new maf is in, code been deleted and haven't come back since.
This was 2-3 weeks ago. Cars been sitting.
And I've been on google/t6forum learning and searching..

2 days ago a rented a vcds cable and downloaded the software. I played around and did some basic testing and logging. Not easy alone.. but need some help/advice on what too logg.

My thoughts from countless hours of searching.

- clogged dpf og unfinished prosess regeneration?
- boostleak/vacuum leak.
- sticking actuator/wastgate (turbo)
- leaky old injectors
- clogged old fuel filter (probably 40-50.000 km old) new is ordered and will be swapped.
- one or both fuel rail sensors
- HPFP (maby off on timing if it will be affected)
- timing (We didn't have the correct locking tool, but used timing marks on plastic cover) turned engine multiple times and cam locking pin went straight in.

what's your thoughts..

I have some logging data, but not sure if it is with the right parameters.. need help with this.

 

[St6]

I had a similar thing years ago ,and turned out to be the map sensor in the intake manifold mine was dirty once cleaned sorted my problem .worth a go.

 

[mr.change84]

I had a similar thing years ago ,and turned out to be the map sensor in the intake manifold mine was dirty once cleaned sorted my problem .worth a go.

Will do..

 

[mr.change84]

@mmi, may I bother you with this problem.
I've seen countless of threads with you helping people with vcds setup on what to log or just helpfully tips.

A have some logging files, but don't know if parameters are correct or what I'm looking for

 

[The Bear78]

Belt was split, but not broken off.

After inspecting the camshaft modul, we found it was twisted.

I don't understand this bit. I assume that you weren't allowed to try and start it when you looked at it?

I'm not trying to cast a shadow over your purchase but I do wonder if the belt snapped and bent the engine. Another belt could have been put on and purposely split to try and pass it off as a close call.
It would be beyond immoral but, sadly nothing would surprise me from some dealers.

 

[mr.change84]

I don't understand this bit. I assume that you weren't allowed to try and start it when you looked at it?

I'm not trying to cast a shadow over your purchase but I do wonder if the belt snapped and bent the engine. Another belt could have been put on and purposely split to try and pass it off as a close call.
It would be beyond immoral but, sadly nothing would surprise me from some dealers.

Hi,
We bought the car maby 2 weeks after this had happened and the car had not been touched, other then removing the top cover of timingbelt.

Toothed belt had "splitt sideways" at really low rtm, going into a roundabout at low speed.

We bought it directly from the use, and no we didn't attempt to start it with the broken belt. Towed it home.

Regarding camshaft-modul, it's normal for them to twist. It's in there design, too prevent more engine damage. the lobes slippes on the cams. They are just press fitted.

If timingbelt snaps at high rpm, often valve roller also brakes.. they are designed too do so.
All of ours was inspected and found 100% fine.

 

[mr.change84]

I had a similar thing years ago ,and turned out to be the map sensor in the intake manifold mine was dirty once cleaned sorted my problem .worth a go.

was it number 21 at the air box or 28 at the manifold.
are bouth MAP's?

 

[The Bear78]

Toothed belt had "splitt sideways" at really low rtm, going into a roundabout at low speed

How did the driver know?

 

[mmi]

@mmi, may I bother you with this problem.
I've seen countless of threads with you helping people with vcds setup on what to log or just helpfully tips.

A have some logging files, but don't know if parameters are correct or what I'm looking for

Let's start by grabbing all the engine parameters (engine blockmap)

Please post

(1) - engine's blockmap data - engine not running (ignition on)​

(2) - engine's blockmap data - engine ticking over (idling 830 RPM)​

VCDS > Applications > Controller Channel Map >

Tick/fill boxes as above and click Go.

VCDS flashes screens for a moment (when finished hit "Done, Go Back") and there should be files blockmap-01-... in folder C:\Ross-Tech\VCDS\Logs\....

PS. For the above either VCDS HEX-V2 or HEX-NET cable is needed.

 

[mr.change84]

How did the driver know?

Engine stopped running immediately.
And when he tried start it again wouldn't start.
(Reason of corse what timing was off about 20-40° due to twisted cam.)
Called a tow truck and rest is history.
Think one of the other employees had a code reader and do motorsporting. And he checked under the timingbelt cover. (Cover was off when we saw it 1.time.)

 

[mr.change84]

Let's start by grabbing all the engine parameters (engine blockmap)

Please post

(1) - engine's blockmap data - engine not running (ignition on)​

(2) - engine's blockmap data - engine ticking over​

VCDS > Applications > Controller Channel Map >

Tick/fill boxes as above and click Go.

VCDS flashes screens for a moment (when finished hit "Done, Go Back") and there should be files blockmap-01-... in folder C:\Ross-Tech\VCDS\Logs\....

PS. For the above either VCDS HEX-V2 or HEX-NET cable is needed.

Will do when renting the hex-v2 cable next time.
Need it when swapping fuel filter.

question: nr 1 okay, but nr 2? what do you mean by engine ticking over.. is this engine at idle (827rpm)

A have some CSV files that a logged on Wednesday this week. How good it is or if correct parameters are there, I think only you can answer.

Will post them as soon as I can home..

And again.. thank you so much for your help

 

[mr.change84]

@mmi

log files from earlier this week (first time using vcds, but learning)

 

[mmi]

but nr 2? what do you mean by engine ticking over.. is this engine at idle (827rpm)

Yes, correct - engine idling (thus about 830 rpm)

He said erg valve was 28% open at idle and was probably stuck open and the cause of this..

Well, at idle the EGR is at about 30% normally. Also a stuck valve would probably trigger a fault code.

EGR Valve Self Test Procedure (IDE00242)- P046C?

So, I've been getting the all too common P046C fault code along with P2457 (Insufficient EGR Cooling Performance). Neither alone will flag a check engine light but combined they sometimes seem to. To try to figure out what is going on, I ran an EGR Flow test on VCDS using instruction from @mmi...

www.t6forum.com

plan all along was erg delete and stage1/soft tune due to trailer towing.

So I called a nearby, well known Norwegian tuner and they helped me with this.

What was done?

My thoughts from countless hours of searching.

- clogged dpf og unfinished prosess regeneration?
- boostleak/vacuum leak.
- sticking actuator/wastgate (turbo)
- leaky old injectors
- clogged old fuel filter (probably 40-50.000 km old) new is ordered and will be swapped.
- one or both fuel rail sensors
- HPFP (maby off on timing if it will be affected)
- timing (We didn't have the correct locking tool, but used timing marks on plastic cover) turned engine multiple times and cam locking pin went straight in.

- HPFP (maby off on timing if it will be affected)

Not likely.

- timing (We didn't have the correct locking tool, but used timing marks on plastic cover) turned engine multiple times and cam locking pin went straight in.

Based on the log the timing seems to be "good enough" - not causing any problems. Ideally the position would be at zero.

​

​

At 2k rpm it feels like "missfire" or small fuel cuts, or lack of boost from turbo and some small vibration from the engine. Hard to explain.

Check this thread please - possibly some similarities?

204 DSG intermittent momentary power loss

If you floor it in neutral, the engine won’t spin up as quickly as that so it definitely cannot do it under partial/full load. Correct. But if you think the case of accelerating, pedal at 80% or so, rpm is limited and resisted by the torque through gearbox and ultimately grip on the road...

www.t6forum.com

Will do when renting the hex-v2 cable next time.
Need it when swapping fuel filter.

Already seen this below?

[T6_measured] 01-Engine - Built-in test for Transfer fuel pump

A quick DIY way to test fuel lift pump's basic functionality. The test takes advantage of engine's fuel high pressure sensor (in fuel rail). Running the lift pump continuosly makes the pressure eventually "leak" through high pressure pump and can be detected by fuel pressure sensor. As a side...

www.t6forum.com

 

[mr.change84]

Well, at idle the EGR is at about 30% normally. Also a stuck valve would probably trigger a fault code.

EGR Valve Self Test Procedure (IDE00242)- P046C?

So, I've been getting the all too common P046C fault code along with P2457 (Insufficient EGR Cooling Performance). Neither alone will flag a check engine light but combined they sometimes seem to. To try to figure out what is going on, I ran an EGR Flow test on VCDS using instruction from @mmi...

www.t6forum.com

plan all along was erg delete and stage1/soft tune due to trailer towing.

So I called a nearby, well known Norwegian tuner and they helped me with this.

What was done?

they downloaded my ecu's oem software file, and custom tuned it to stage1. erg was blocked with steel plate (at manifoil side, not exhaust side) and programmed out erg

 

[St6]

Sensor 28 in inlet manifold

 

[mr.change84]

Sensor 28 in inlet manifold

Did you remove it from the top or underneath.

I was thinking to clean it with maf cleaner.

 

[St6]

From top ,yes clean it with that.

 

[mmi]

A proposal for data logging

For genuine VCDS HEX-V2 or HEX-NET​

Turn IGN on -

VCDS > Select > Engine > Advanced Measuring Values

tick the following data items​

IDE00021 Engine RPM​

IDE00075 Vehicle speed​

IDE00347 Air mass: actual value​

IDE00352 Main injection: duration of activation​

IDE00406 Camshaft RPM​

IDE00472 Mean injection quantity​

IDE00589 Fuel pressure​

IDE04685 Setpoint generation interior torque​

IDE07738 Charge air cooler inlet: pressure sensor 1 bank 1: raw value​

IDE07742 Cylinder head: pressure sensor 3 bank 1: raw value​

IDE07744 Particle filter: air pressure sensor 1 bank 1: raw value​

IDE07757 Exhaust recirc.valve 1 bank 1: posit.feedback - Actual value​

Spoiler: How to save/load the measurement setup

The measurement setup can be saved for the next run - click on top left corner (Save/Load)

Tick Group UDS requests - by 7 (IMPORTANT!!!)

Log > Start

Start the engine - switch the Stop/Start off

​

Let the engine idle for 2 minutes.​

Do the journey - while logging is active there is a "Marker" button to make a stamp into the log e.g. moments of misfires - helps to search the suspicious moments.​

​

Let the engine idle for 2 minutes.​

Stop logging.

The log file will be stored in folder C:\Ross-Tech\VCDS\Logs

---

A simulated VCDS to get a grab on what/how to do

Ross-Tech: VCDS Tour - Main Screen

 

[mr.change84]

@mmi how log journey do you need.
5 min normal driving or 30min.
or multiple hard pulls in 3. and 4. gear

 

[mmi]

5 minutes normal driving would be a good reference. A couple (2-5) of hard pulls to demonstrate the issue would be ideal. All of them can be in a single log. Some bookkeeping would be helpful - to time stamp when the issue surfaced - see the "Marker" above.