Smoking engine after engine/turbo replacement

Hello everyone,
It's me again.
And now, let's talk about my brother's car: a Volkswagen Golf TDI with a 103kW CFFB engine.


Briefly, here's some background information (if you're not interested, just skip to the next line after the dash):
Four weeks ago, a badger got into the car at night and chewed through a wiring harness located behind the left headlight. I replaced the connectors and repair wiring, cleaned the area including the removed wheel arch liner, and then went for a test drive.
So far, everything was fine. I drove along the country road to the neighboring town and then back via the highway. I was just about to overtake on the left lane when the engine suddenly stopped responding to the accelerator for a short time. For some reason, I pressed the clutch and mentally prepared to pull over to the shoulder when the engine speed, along with a huge cloud of smoke, suddenly shot up to the maximum on the tachometer. I tried briefly to shift into 6th gear and slow the engine down, but it didn't really work, and I was also hesitant to start experimenting with heavy braking at 140 km/h.
The end result... less than 10 seconds later, the internal components of the engine were scattered across the highway and its shoulder, and approximately 5 liters of engine oil covered the entire car.
Police, fire department, tow truck... the whole shebang .

Cause (at least that's my suspicion): The turbo was the culprit. At least the verschandeln air side was completely full of oil, the shaft had excessive play, and there were significant scratch marks on the exhaust side.

The oil pan was blown off, connecting rod parts were lying on the steering linkage, and there's a fist-sized hole in the engine block between cylinders 2 and 3. On the rear side, you can see the crankshaft, along the entire width of the engine, with connecting rod fragments, pistons, and what remains of the engine block, all the way up to cylinder 4. Anyone who would like can get pictures.

After a long search (a naturally aspirated engine without a turbo, injectors, high-pressure pump, and vacuum pump from VW alone costs 4500€), I finally found an engine rebuilder who was friendly, competent, and not a parts reseller/scrapyard that had a CFFB engine (with supposedly 55,000 km) available at a reasonable price.
Two days later, the engine arrived via freight company. Visually, the 55,000 km mileage seemed consistent with the engine. After installing new filters, seals, a new clutch, and a new dual-mass flywheel (DMF), everything was reassembled, and it was ready to go.

The new engine came with a high-pressure pump and injectors. I then performed the fuel system bleeding process three times using VCDS, entered the correction values for the new injectors, tested the radiator fan, filled and bled the cooling system... and pressed the start button.

The idle was extremely unstable (fluctuating around 200 RPM). As soon as you gave it a little gas, the engine ran perfectly. But if you gave it a bit more, the engine check light would immediately start flashing.
Error: Rail pressure too HIGH.

Since it was late and the boss had already finished preparing the food, I continued the next day. I vented the system two more times using VCDS, and then restarted it again. The idle speed is correct and set at 780 RPM, but the rail pressure error still occurs when the RPM exceeds 1500.
I then simply let the engine run in neutral for 90 minutes, also to check if everything was leak-free. Whatever the reason, the rail pressure error disappeared afterward.
Test drive: Everything's good. Engine runs smoothly, idle speed is correct at traffic lights, clutch engages properly...
I properly detailed the car over the weekend and was happy that this whole ordeal would finally have a good ending.

Please provide the German text you would like me to translate into English.
Okay, from here things get interesting:

This morning, I wanted to do some more extensive testing before my brother gets the car back.
"About 2km after the start, the oil temperature was around 55°C, and I noticed that the engine was smoking quite a bit. It was difficult to stop at that point." And then there's this smell of burnt plastic, like the particulate filter is currently regenerating.
I had my laptop with the VCDS cable plugged in, still in the glove compartment, and I saw: soot mass was well over 20 grams.
Okay, let's get on the highway and first clear the particulate filter. That went quite well. Unfortunately, the smoking didn't stop.
I took a detour past and interviewed the master there.

He pointed out the discrepancy in the fuel injection amounts.

30 minutes after I got home, I checked there again:
Motor speed: 779 RPM.
Oil temperature: 60°C.
Fuel injection deviation, cylinder 1: 0.18mg/stroke.
Fuel injection deviation, cylinder 2: -0.17 mg/stroke.
Fuel injection deviation, cylinder 3: 0.46mg/stroke.
Fuel injection deviation, cylinder 4: -0.47 mg/stroke.

It looks good at first glance.
Briefly tapped and held the accelerator... again, all values are OK.

During the engine's idle phase, I noticed an unusually uneven engine running.
Motor speed: 825 RPM.
Oil temperature: 69°C
Fuel injection deviation, cylinder 1: -0.21 mg/stroke.
Fuel injection deviation, cylinder 2: -0.35 mg/stroke.
Fuel injection deviation, cylinder 3: 1.09 mg/stroke.
Fuel injection deviation, cylinder 4: -0.69 mg/stroke.
That happened while the engine was returning to its idle speed after the sudden acceleration. The erratic engine running also disappeared after a few seconds, and the values then matched the initially mentioned ones.

The oil ash volume in the DPF is 0.10 liters after 175,000 km. (VW said this doesn't seem right, as it should be higher, but the car is only from 01/2012, so the previous owner likely drove it mostly on the highway).

Does anyone have any ideas about what else I could do here, and where the smoke might be coming from? Is it normal for the fuel injection deviations to be so different when accelerating or decelerating? I'm reluctant to take the car to the workshop because there's a risk of them replacing parts unnecessarily (like injectors or the DPF), which could end up costing us thousands of euros, and the actual problem might have been something very simple.

The car otherwise drives perfectly, has full power, and doesn't register any error codes.


Best regards,
Lars.

Was the particulate filter replaced, or was it taken from the scrapped engine?
hg
Herbert.

Hello Herbert,
This is the old particulate filter. Since the turbo wasn't oily on the exhaust side, and didn't blow any debris or particles into the DPF, I decided to leave the DPF in place.


VG
Lars.

Despite this, the damage description likely indicates that the DPF is clogged.
hg
Herbert.

Are you suggesting that the smoke is being caused by oil residue in the DPF that is currently being "burned off"?

What surprises me is... Why did the car, which stood still in the driveway for 90 minutes and during the final 10km/15-minute test drive, not produce any smoke at all, but then started smoking after only 2km three days later?

The fuel injection volume deviations are within my acceptable range, especially since the engine is not yet fully at operating temperature. Is the TL an original ET?
You can try to verschandeln the DPF by burning it out over time.
hg
Herbert.

The turbocharger came with the "new" engine and looks new to me, or at least professionally refurbished, compared to the one that was installed with 175,000 km on it. It was so clean, you could eat off of it.
The VTG linkage is also working smoothly; I tested that at the beginning using the actuator diagnostics.

I just want to avoid replacing the DPF unnecessarily. By "cleaning," I obviously don't mean a service regeneration (which would probably get too hot), but rather an extended drive on the highway. If that helps, a trade is still necessary.
hg
Herbert.

"I can certainly try that, but I suspect it will be a complete disaster."

I really don't want to break anything again... I've already spent enough money on this car in the last 3 weeks .

Then we would drive at night.

And if there's something wrong with the engine, you're probably covered by a warranty. It's better to have something break now than later.

What does the smoke smell like, oil or diesel?
If you want to be absolutely sure.
- Check the exhaust gases coming from the turbocharger for oil (remove DPF/catalytic converter).
- while simultaneously performing a visual inspection of the removed parts;
- Check fuel injection system (rail pressure: target/actual values, injectors: deviations in switching time correction, return flow rates, fuel injection quantity correction at cold and warm temperatures).

hg
Herbert.

Hi,

Please pressurize the intercooler system, otherwise hidden damage from rodents or other leaks might open up under sufficient boost pressure, allowing pressurized air to escape and overstress the turbocharger.
and furthermore, it can cause too little combustion air in the engine, which means increased soot production.

Best regards, Rainer.

You wrote that the turbo forced oil into the intake manifold, and then the engine over-revved due to its own oil. Consequently, he inhaled the oil and also expelled it from his body (partially burned, partially unburned).

It's now stuck in the exhaust system or DPF. I have no idea how much ash the DPF can tolerate. However, based on a maximum ash content of 60g, the oil likely completely filled the DPF. What does the differential pressure reading at the particulate filter indicate in the measurement data blocks?

PS: In vehicles without a DPF, the entire exhaust system was often oily inside in such cases. The smoke was very thick and lasted for a long time (until even the last part of the exhaust was so hot that the oil had completely evaporated).
I still consider the smoke (if it's blue) to be somewhat normal, but I can't believe the DPF could have survived that. I'm very eager to see the results.

Good morning!

Okay, let's get started.

Smell:
As mentioned above: It's neither gasoline nor diesel. More like the smell of burning plastic during a DPF regeneration.



Values for an engine running at idle in a cold state:
Motor speed: 780 RPM.
Oil temperature: 20°C
Fuel injection deviation, cylinder 1: -0.04 mg/stroke.
Fuel injection deviation, cylinder 2: 0.22mg/stroke.
Fuel injection deviation, cylinder 3: 0.05 mg/stroke.
Fuel injection deviation, cylinder 4: -0.24 mg/stroke.
Particulate filter differential pressure: 7 hPa.
Fuel high pressure actual value: 307500 hPa.
Fuel high pressure target value: 321400 hPa.

Values from a cold engine at 2500 RPM:
Motor speed: 2495 RPM.
Oil temperature: 23°C.
Fuel injection deviation, cylinder 1: -0.33 mg/stroke.
Fuel injection deviation, cylinder 2: 0.32mg/stroke.
Fuel injection deviation, cylinder 3: 0.75mg/stroke.
Fuel injection deviation, cylinder 4: -0.73 mg/stroke.
Particulate filter differential pressure: 19 hPa.
Fuel high pressure actual value: 791100 hPa.
Fuel high pressure setpoint: 788500 hPa.

Now, here are the values (highlighted in bold) that I find a bit surprising. When slowly reducing the engine speed from 2500 RPM down to idle, the engine runs roughly from 1300 RPM down to idle. However, after 5 seconds at idle, it runs smoothly again, and the values return to what was mentioned initially.

Motor speed: 783 RPM.
Oil temperature: 26°C.
Fuel injection quantity deviation, cylinder 1: -0.47mg/stroke
Fuel injection deviation, cylinder 2: 0.09mg/stroke
Fuel injection deviation, cylinder 3: 1.05mg/stroke
Fuel injection deviation, cylinder 4: -0.57mg/stroke
Particulate filter differential pressure: 8 hPa.
Fuel high pressure actual value: 175600 hPa
Fuel high pressure setpoint: 325700 hPa



@dieselschrauber: Where can I find the deviation values for the shift time correction? I can't seem to find them in the documentation. There are no comparable measurements.

I can check the intercooler piping after the weekend. However, since I've manually cleaned all the hoses and pipes and carefully inspected them for weasel bites, I'd almost rule that out as the cause. Installation errors are also a possibility.


@guste100:
You are absolutely right, I had suspected as much. The old, defective turbocharger is "bone dry" on the exhaust side and literally deer-brown in color. I looked inside the DPF with an endoscope, and nothing suspicious or shiny was visible there either. There are absolutely no signs of unburned oil in the turbocharger, DPF, or exhaust pipes. Of course, I agree with all of you that the burned oil had to go somewhere!
I have added the difference expressions above.
The smoke is more white than blue. I'm going to try riding during the day again over the next few days and take a picture.


Best regards,
Lars.

Hello Lars,

Quote:

@dieselschrauber: Where can I find the shift time correction deviations? I'm looking for them in the relevant documents. No measurements of anything similar.

in the extended measurement data blocks of the engine control unit. Since a large number of data points appear there, the search may take some time.

Quote:

Fuel injection deviation, cylinder 1: -0.47mg/stroke. Fuel injection deviation, cylinder 2: 0.09mg/stroke. Fuel injection deviation, cylinder 3: 1.05mg/stroke. Fuel injection deviation, cylinder 4: -0.57mg/stroke

Okay, please provide the German text you would like me to translate.

Quote:

Fuel high pressure actual value: 175600 hPa Fuel high pressure setpoint: 325700 hPa

A log would be appropriate; from the snapshot, it's difficult to draw any conclusions other than that the deviation from the rule was significant at that point in time.

Highlight meaningful data points.
Okay, I'm ready. Please provide the German text you want me to translate.

Best regards, Rainer.

I'm completely new to logs... Ulf explained it to me once in a neighboring forum, but I still don't really understand it. I'll see when I can find the time to deal with it, and of course, I'll upload all the relevant data here when I do.


VG
Lars.