Lumpy engine start and idle

[mmi]

1.2 ° is ok then?

Yes, actually even "better" than on mine having renewed the timing belt three months ago, and definitely not the culprit for lumpy running.

Need to be cleaned or cleaner through it? or a different type of regen?

Perhaps could try what a forced DPF regeneration while driving would do? But would like to make a recordings "before and after" to see if it improves the situation. Let me know so can prepare a dataset for VCDS.

VW Techs have to follow there own routes, but hopefully will save time and money

Correct, VW techs also have a database of possibly similar symptoms.

So my thinking from tests and the data is that the issue is with cylinder 4/injector 4, because it not working fully at start, its throwing the ECU out and that makes the other cylinders/injectors work hard throwing them out too, until cylinder 4 comes back then they all run correctly.

This is what i'm hoping and injector being replaced fixes it.....

The injector 4 is something to check anyway. A possibility to further diagnose would be to swap injector 4 with another one (perhaps with cylinder 1, because of firing order 1-3-4-2) and check if the suspect location follows. However, not sure if swapping makes economically sense.

Meanwhile, perhaps you could redo a cold lumpy startup (same as LOG-02) at least once more - just to build confidence the measurement data we saw about "IDE09330 Cylinder 4 bank 1 internal moment" sticks with cylinder 4.

I agree with the theory - it's just a challenge to pinpoint the culprit because ECU indeed tries to compensate possibly one being partially out. Also the flywheel mass itself resists speed changes, and finally dual mass pendulums swinging back and forth probably even further blur what we see in the data

Anyways, I do appreciate you collecting and sharing the data - I'm hoping we eventually can conclude a method to pinpoint where the issue is - possibly the internal moment calculated by ECU is the key.

---

The parameter "Fuel injection time deviation:" have been tried to use to pinpoint possibly a faulty injector - but not successfully - I think. Anyways, below the plots for the earlier logs: LOG-02 (lumpy), LOG-04 (smooth).





In LOG-04 the cylinder 4 curve is suspiciously "too flat" - perhaps it's at the limit of it's allowed adjustment range.

---

Also below the calculated deviations based on "IN_Injection_speed_injector". Although also these seem to point the same cylinder I'm trying to understand the justification for this

Lumpy


Smooth

 

[shaiboyuk]

Van went into VW garage this morning
Gave them print out of the data, hopefully it helps them.....
Said if injector faulty it would be covered under All-In warranty, fingers crossed.

Have a T6.1 "Highline" panel van to run about in while I wait.

Meanwhile, perhaps you could redo a cold lumpy startup (same as LOG-02) at least once more - just to build confidence the measurement data we saw about "IDE09330 Cylinder 4 bank 1 internal moment" sticks with cylinder 4.

Done another couple of recordings (attached) before taking van to garage and saved the setting so can load when doing it next time

Log-06
IDE09327, IDE09328, IDE09329, IDE09330 etc
IGN ON, then cold start (3 degrees), Idling.
Lumpy, of course, but by end of 3 minutes seemed better.

Log-07
IDE09327, IDE09328, IDE09329, IDE09330 etc
Idling then raising RPM to above 2000RPM x2
Wanted to see what data would show when going above 2000RPM when its lumpy, but by this point it was less lumpy.

I agree with the theory - it's just a challenge to pinpoint the culprit because ECU indeed tries to compensate possibly one being partially out. Also the flywheel mass itself resists speed changes, and finally dual mass pendulums swinging back and forth probably even further blur what we see in the data

Hoping not Flywheel or Dual Mass as this sounds expensive and probably not covered under warranty :/
I did dip clutch when it was lumpy to see if it changed or was noisy, thankfully it made no difference.

 

[mmi]

Log-06
IDE09327, IDE09328, IDE09329, IDE09330 etc
IGN ON, then cold start (3 degrees), Idling.
Lumpy, of course, but by end of 3 minutes seemed better.

 

[mmi]

Log-07
IDE09327, IDE09328, IDE09329, IDE09330 etc
Idling then raising RPM to above 2000RPM x2
Wanted to see what data would show when going above 2000RPM when its lumpy, but by this point it was less lumpy.

Cylinder 4 again - from 10 to 25 seconds lagging behind.

 

[shaiboyuk]

View attachment 272399

Cylinder 4 again - from 10 to 25 seconds lagging behind.

So same :/

Day 3 of van being in garage and advising injector 4 failed on testing..... Extended warranty (All in) have now approved, but might be into next week before fitting new one :/

Is it a big job fitting a new injector? I know it needs coding.

Hopefully it's the correct fix

 

[mmi]

Is it a big job fitting a new injector? I know it needs coding.

Two hours maximum for the actual hands-on work.

 

[shaiboyuk]

Two hours maximum for the actual hands-on work.

Hopefully they get a spare 2 hrs before weekend then :/ not liking driving a panel van lol

 

[shaiboyuk]

A small update....

Update from VW garage:
They have fitted the injector and built it back up but isn’t running right.
They have found a crack at the back of the rocker cover thinks It’s probably a stress fracture or been nicked when been removing or building back up.
They have ordered new one and hopefully get it fitted later today.....

Would a crack in rocker cover cause it not to run right?
Always thought rocker cover was more oil related for top of engine, so should affect running.

Here's hoping.....

 

[shaiboyuk]

Another update from garage.

rocker cover replaced but still not running correctly
so monday, fuel tank getting dropped to check for metal in fuel and will be doing compression test....

really don't understand, if it was fuel or cylinder related, surely it won't clear itself after a period...?!?!?

 

[manfrotto]

Van went into VW garage this morning
Gave them print out of the data, hopefully it helps them.....
Said if injector faulty it would be covered under All-In warranty, fingers crossed.

Have a T6.1 "Highline" panel van to run about in while I wait.



Done another couple of recordings (attached) before taking van to garage and saved the setting so can load when doing it next time

Log-06
IDE09327, IDE09328, IDE09329, IDE09330 etc
IGN ON, then cold start (3 degrees), Idling.
Lumpy, of course, but by end of 3 minutes seemed better.

Log-07
IDE09327, IDE09328, IDE09329, IDE09330 etc
Idling then raising RPM to above 2000RPM x2
Wanted to see what data would show when going above 2000RPM when its lumpy, but by this point it was less lumpy.



Hoping not Flywheel or Dual Mass as this sounds expensive and probably not covered under warranty :/
I did dip clutch when it was lumpy to see if it changed or was noisy, thankfully it made no difference.

The flywheel is on the engine side of the clutch, so dipping the clutch won't make a difference if that is where the issue is.

 

[mmi]

will be doing compression test..

really don't understand, if it was fuel or cylinder related, surely it won't clear itself after a period...?!?!?

Less optimal compression - thus non-optimal combustion when cold would certainly get better when engine has warmed up a bit.

 

[shaiboyuk]

Sorry for not an updates, into the 4th week with van in at VW and small update from garage...

Should have the diagnosis confirmed by today (Tuesday). They didn’t find any signs of swarf at the metering valve but said it can sometimes be full of shavings in the tank. So dropping tank finally. They will do an engine compression test as well to rule the engine out.

Hopefully will know more today...

 

[Dm85]

View attachment 272396

View attachment 272397

View attachment 272398

View attachment 272399

Cylinder 4 again - from 10 to 25 seconds lagging behind.

Hi MMI,

Seen as you’re the go to man. I’ve been monitoring injector time deviations and noticed when it’s doing a regen injector 4 is -43 and the other ones are all positve. Does this indicate an issue with injector 4? Or is this normal during regen? Deviations are less drastic when idling normally (no regen)

 

[mmi]

Hi MMI,

Seen as you’re the go to man. I’ve been monitoring injector time deviations and noticed when it’s doing a regen injector 4 is -43 and the other ones are all positve. Does this indicate an issue with injector 4? Or is this normal during regen? Deviations are less drastic when idling normally (no regen)

I don't fully understand what the parameters mean and how to interpret those into something conclusive.
I guess they basically indicate just how much injection time deviates in each cylinder from mean injection time. Note: it seems that sum of the deviations = 0.

So possibly the ECU has determined that cylinder 4 needs slightly less fuel than the others to run smoothly?? I think it's not necessarily the injector to blame as it seems to be well within it's adjustment range. Possibly the deviations are because of differences in compression of cylinders.

Anyways, any issues or just curious?

 

[n10n]

So possibly the ECU has determined that cylinder 4 needs slightly less fuel than the others to run smoothly??

I’ve always read these deviation values to signify earlier (negative) or later (positive) injection moment rather than adjusting the quantity (ie deviation of injection duration).

Annoyingly, we just have to guess.

 

[Dm85]

I don't fully understand what the parameters mean and how to interpret those into something conclusive.
I guess they basically indicate just how much injection time deviates in each cylinder from mean injection time. Note: it seems that sum of the deviations = 0.

So possibly the ECU has determined that cylinder 4 needs slightly less fuel than the others to run smoothly?? I think it's not necessarily the injector to blame as it seems to be well within it's adjustment range. Possibly the deviations are because of differences in compression of cylinders.

Anyways, any issues or just curious?

the engine definitely has a prominent vibration to it especially cold start. No fault codes, oil loss, no smoke from exhaust. There’s blow by and a diesel smell from oil filler. Regens every 130 miles no matter what with a mixture of long and short journeys. Had a relative compression done and all peaks seem ok to me. Injector seals replaced, Sporadic P20EE only after a long journey. Garage said peaks look ok? I have had the van since new 150 CXHA DSG. 65k miles.

Thanks for your advice

 

[mmi]

Had a relative compression done

Garage said peaks look ok?

Did the garage have pass/fail criteria - delta amps between cylinders?

Interestingly there indeed seems to be a pattern - I think. Green = max amps drawn for a cylinder, blue = min amps drawn for another cylinder. Anyways, I don't know what delta would be good or bad.



PS. Thanks for sharing

 

[Dm85]

Did the garage have pass/fail criteria - delta amps between cylinders?

Interestingly there indeed seems to be a pattern - I think. Green = max amps drawn for a cylinder, blue = min amps drawn for another cylinder. Anyways, I don't know what delta would be good or bad.

View attachment 275393

PS. Thanks for sharing

I did notice that one cylinder is slightly higher but they seemed think if there was compression loss it would be obviously low on one or more cylinders.

Did the garage have pass/fail criteria - delta amps between cylinders?

Interestingly there indeed seems to be a pattern - I think. Green = max amps drawn for a cylinder, blue = min amps drawn for another cylinder. Anyways, I don't know what delta would be good or bad.

View attachment 275393

PS. Thanks for sharing

They said if there was serious compression loss you’d see it as the peak would be lower and looking at the data 10.56 amps. Not sure what delta amps are? Thanks for looking

 

[Dm85]

While inspecting the timing belt, I noticed a slight lateral wobble at the crankshaft. Since replacing the crank pulley didn't resolve the issue, I began to suspect the timing gear. I then found that the timing belt tensioner has been over-tightened beyond its specified range-it's not positioned within the guide slot as it should be. While the deviation isn't extreme, it's clearly under excessive tension, exceeding the maximum limit in the workshop manual. VW did the timing belt late early 2023. I may query them on that

 

[shaiboyuk]

Ok, Update on my issues....

Tank was dropped and found tank full of swarp (metal pieces). Garage advising need new fuel system.
Compression test done, test was well within tolerance, all cylinders roughly the same bar of pressure.

Garage saying need new injectors, rail, pipes, lines, fuel pump and tank cleaned (repair manual does not say to replace tank) and 35L of new fuel. Losing the 60L of fuel that was in tank

Waiting to hear back from extended warranty, the garage needs to run "Test Plans" eg they ask the garage to do a magnet test which involves taking a fuel sample, putting it in a machine which tests the volume of swarf per measurement of fuel, as the claim is around £5k and takes a day and half in labour.....

Now into the 5th week without van, think van has spent a total of 4 hrs in garage, rest of time parked up .

Really missing van, as wanted to go away at weekends
HURRY UP lol