Cold weather, engine runing rough

[Le_Combattant]

This is what I usually do, buy original VW spare parts, although for testing and other purposes I also buy parts from the brands that VW uses on Autodoc, Amazon, Ebay, etc...

For one reason or another, at the moment I am 99.99% satisfied with the purchases I made at Autodoc, in addition to the good customer service.
I think it's a good place for delicate pockets.

For engine, cabine etc...: VW

For other parts: Autodoc.

Las time I had to change my breaks setup (pads and discs). The car was in maintenance and I knew about the wear of my breaks.
My dealer ask me of 800 euros to change everything.

Lmao.

I went on Autodoc, buy ATE disc and pads: 220 euros. I replace all myself.

[Le_Combattant]

Here I am again with my car

The cold weather is back and with it the rough running
After changing:
-Coils (x4)
-Spark plugs (x4)
-Pressure/temperature sensors (x2)
-TDC sensor

The problem is still the same.

My father didn't believe me, so he came with me and took the driver's seat.
He quickly realised that (when cold) he was getting what I was describing to him.
Between 1,000 and 2,000 rpm with a jerky engine that struggles to get up to speed in all gears.
It's sneaky but enough to notice.

No misfires recorded.

Once the oil is 'hot' (from 60-65°C), the problem diminishes until it disappears completely when hot.


I admit I don't really know where to look, but I've already ruled out several possibilities:

-HP pump: the pressure requested and sent by the pump is good.
-Turbo: the pressure requested and sent by the turbo is good and constant.

Remaining suspects:
-Throttle (cleaned a short time ago and showed no resistance or anomaly when I handled it)
-Lambda sensors (my knowledge here are limited)
-Wastegate actuator (on these engines it tends to get stuck. However, it moves freely by hand and after readaptation to the OBD, it's OK).

I'm also thinking of doing a compression test to see how healthy the engine is.

[ciclo]

Do you know if there is any more up-to-date software available for your engine electronics unit?
Do you have a scan of your engine to check it?

[Le_Combattant]

Do you know if there is any more up-to-date software available for your engine electronics unit?
Do you have a scan of your engine to check it?

I dont know if an update still exist today.
For the scan, I just have my OBDeleven

[Maarten]

Did they use the right oil in the recent servicing?
Because problem seems to disappear when oil is hot (and thin enough)

[Le_Combattant]

Did they use the right oil in the recent servicing?
Because problem seems to disappear when oil is hot (and thin enough)

I perfomed the last oil change.
0W30 504/507 from Shell.

The problem is only when outside temp are near of below 0°C

[Le_Combattant]

The doc requires the battery to be above 12V and the oil above 30°C. At that point I must have been around 80-85.

We dismantle everything: filter, coils, spark plugs and off we go:

PXL_20240122_145053243.jpg (3.53 MiB) Viewed 8733 times

Cylinder 1:

PXL_20240122_145224097.jpg (2.59 MiB) Viewed 8733 times

About 15.5 kg/cm2 or 15.2 Bar.

Cylinder 2:

PXL_20240122_150749300.jpg (2.75 MiB) Viewed 8733 times

Approximately 15.3 kg/cm² or 15 bar.

Cylinder 3:

PXL_20240122_151024550.jpg (2.77 MiB) Viewed 8733 times

15.5 kg/cm² like cylinder 1.

Cylinder 4:

PXL_20240122_151204975.jpg (2.55 MiB) Viewed 8733 times

15.2 kg/cm² or 14.906 bar

! WARNING!

The pressure gauge has not been calibrated by me, so the values may be wrong (optimistic or pessimistic: your choice :Red: )
I'm going to choose to be optimistic :lol!

Note that I did two tests per cylinder. Each time the results were identical.

[Le_Combattant]

I think I found the issue:...

Cylinder 1 and 2.
3 and 4 are the same.

PXL_20240213_101922241.jpg (2.93 MiB) Viewed 8527 times

PXL_20240213_101953006 (1).jpg (2.43 MiB) Viewed 8527 times

I take an appointment to clean my valve with dry ice.
And I will add a catch can because it's a mess. Do you know why kind of/model I could buy ?

[RUM4MO]

Not walnut shell blasting?

What is the current Kms this car/engine has run from new?

I don't know which catch tank works best.

Edit:- you will be able to check that the HP fuel rail fixing bolts are torqued up correctly as that was a possible issue with this engine from new, plus you should buy new inlet gaskets.

Edit:- ignore the Kms question, looks like roughly 150,000Kms by now, so probably a good time to carry out walnut shell blasting of the inlet areas, maybe no justification to bother about fitting a catch tank.

[Le_Combattant]

Not walnut shell blasting?

What is the current Kms this car/engine has run from new?

I don't know which catch tank works best.

Edit:- you will be able to check that the HP fuel rail fixing bolts are torqued up correctly as that was a possible issue with this engine from new, plus you should buy new inlet gaskets.

No yet. Because it's my daily I have to found time during my off days.
Like so, they willz come to perform a dry ice cleaning.

And I have all ring, seal needed, intercooler also.

The car has now 149200 km.

[RUM4MO]

Yes, I just looked at your first posting and worked out that it would be roughly 150,000Kms by now.

What other seals or gaskets did you need to buy for the intercooler, when I remove mine, I plan to drain down the coolant as it is G13 and remove the intercooler complete with the inlet manifold and so avoid needing to buy that seal between the intercooler and inlet manifold - or did you want to wash the oil etc out of the inlet manifold - and maybe even the intercooler?

The G13 will be now have turned acidic by now, so maybe better to refill with G12evo, that is what I intend to do this year when the weather is warmer.

[Le_Combattant]

Yes, I just looked at your first posting and worked out that it would be roughly 150,000Kms by now.

What other seals or gaskets did you need to buy for the intercooler, when I remove mine, I plan to drain down the coolant as it is G13 and remove the intercooler complete with the inlet manifold and so avoid needing to buy that seal between the intercooler and inlet manifold - or did you want to wash the oil etc out of the inlet manifold - and maybe even the intercooler?

I already have intakemanifold gasket, throttle body gasket, 2 gasket for the intercooler.

I will remove it from intakemanifold ans drain it/clean it.

I also already switched to G12EVO.

[Le_Combattant]

Hello !

May I wish you a happy ending for this year 2024.

I totaly forgot to give you feedback concerning my situation.

Following the removal of air intake, I decided to book with a company to clean my air intake valve with dry ice. Very efficient and fast process.
After 1 hour, air intake, valves etc...everything was litterally brand new and shiny.

429808806_364508369736179_6984392275769002795_n.jpg (196.3 KiB) Viewed 7914 times

*Same for the 3 other intake

After a road test, the car, the engine: both were feeling brand new.
Torquy, nice response from engine.

The issue was gone...until few days ago when temp drops near 1 to -1/2°C.

I had the same exact feeling with engine hesitation below 2000 rpm.
So for sure something doesn't like cold weather or is sending wrong data to engine ECU.

As engine more and more hot, hesisation tend to desapear and when at operating temp, no issue to report.

For info, I changed (before the intake cleaning):

-4 Coils
-4 sparks plugs
-Solenoid valve for the intak cam
-TDC sensor

I had to make some logs with my VCDS to see what kind of parameters could impact engine management.

[RUM4MO]

That cleaning away the carbon seems to have been successful - as far as clearing the inlet tracts.

Maybe check with VCDS what the car thinks the coolant temperature and any other inlet temperature measuring sensors are seeing.

Even although I claimed that I'd be checking the inlet areas on my wife's 2015 Polo 1.2TSI 110PS 6MT "when the weather got warmer" - I spend that "car time" on carrying out a "suspension refresh" - so that really needs looking at next year along with the coolant changing to G12evo - her car has only run 52,000 miles and still drives like new (famous last words).

Seasons Greetings to you!

[Le_Combattant]

All temps reading are correct.

From the air inlet temps to the coolant temp, everything was almost the same at plus/minus 1°C