T4, wise/bluish exhaust smoke

Hello everyone,

Perhaps someone can help me; I'm at my wit's end.

I'm having the following problem with my T4 1.9 TD, 68 hp, manufactured in 1996.
When starting, it smokes white/blue.
Sometimes it's more, sometimes it's less. When it's running rough, it also smokes, as if it's only running on 3 cylinders. It will then decrease again after a short time and with a slight increase in engine speed.
The strong smoke smell only occurs when the car has been standing for several hours (but not always, about 1 out of 10 times).
It's irregular, as there's no consistent pattern to how much he smokes, and there's also no discernible correlation with the outside temperature.

It also smokes excessively while driving.
This phenomenon always occurs and can be simulated or reproduced with some practice. Predict when it will happen.
Always after a gear change, when the engine is in a lower RPM range and simultaneously being accelerated.
This phenomenon can be observed within a narrow range of speeds.
Unfortunately, this is a speed range that I always need when accelerating, so it can't be avoided. I am unable to provide precise speed values due to the lack of a tachometer.

Here are some facts about the car:
The timing belt was recently replaced by a specialized workshop, but unfortunately, the problem persists.
The turbo kicks in noticeably during acceleration.
Oil, or Cooling water has negligible losses.
For example, at higher speeds. No significant smoke plumes are visible from the highway.
Or, acceptable smoke emission, after all, it's not a brand new car .

Does anyone have any ideas about what I should try next?
Unfortunately, the strong smoke is impossible to ignore.

Thank you in advance.
Best regards, David.

Hi,
Can you provide more information, i.e.
- Engine code letter,
- Does the white smoke smell like poorly combusted diesel?
- While driving, is it black smoke or white smoke?

Since you already have VCDS, I assume you can measure the idle speed even during irregular running, and of course, you can also adjust the fuel injection pump (basic setting).

hg
Herbert.

Oil consumption?

Hi!

Yes, I'm somewhat familiar with that engine.
I think ABL was it.

It was actually considered a good engine.
For a car with only 68 horsepower, it performed surprisingly well and was relatively fuel-efficient.
I wasn't aware of any major problems with that.
It's been a long time since I last worked with an engine like this...

Okay, so if there's no oil consumption...
or within a certain range; I'd say something like half a liter per 1000 km would be okay, and then it wouldn't look so bad.

How about the starting behavior?
Does it start properly in cold weather?

Is the motor power also okay?


I know that 20 years ago, these engines were often used in courier services and similar businesses.
Distances of 250,000 km or more were not uncommon. Without any major engine problems.

How many kilometers are currently showing on your odometer?

If I remember correctly, this is a classic swirl chamber turbo-diesel engine.
with classic turbochargers.
It doesn't have an intercooler either.
And I think that VCDS probably won't be able to do much in that regard.
I think these vehicles probably don't have an engine control unit that's capable of diagnostics.

Killer screw?

Steffen G wrote:

Hi! Yes, I'm somewhat familiar with that engine. I think ABL was it. Please provide the text you would like me to translate from German to English. If I remember correctly, this is a classic swirl chamber turbo-diesel engine. with classic turbochargers. It doesn't have an intercooler either. And I think that VCDS probably won't be able to do much in that regard. I think that a motor control unit that is capable of being diagnosed

is something they don't have.

The user could have already told us.

Okay, let's start by checking if the engine is mechanically sound, meaning... KW spur gear tight? (If not, replace with a screw made of a harder material), valve timing (intake and exhaust), compression.
White/blue smoke during startup can be caused by fuel injection starting too late.
hg
Herbert.

Hello everyone,

It's the ABL engine with only approximately 230,000 kilometers.

The smoke smells like unburned diesel.
Oil consumption is negligible, less than 1 liter per 10,000 km.

During the trip, the smoke is a deep black color.

Regarding starting behavior:
In the winter, I don't drive the car.
But otherwise, preheat, one revolution, and then it's running.
I would describe the starting behavior as very good.
My other car (a 2.0 TDI) can't keep up.

Engine power:
I find it a bit sluggish from the bottom end (subjectively), but once the turbo kicks in and the black smoke stops, it pulls surprisingly well.

My layman's speculation...

A misfire at startup, characterized by blue smoke and a rough engine idle ("a reluctant cylinder"), could be caused by a faulty fuel injector. The poor fuel delivery from a faulty injector results in incomplete combustion initially, but the combustion improves as the engine warms up. Similarly, engine oil leaking past a faulty valve stem seal and accumulating on the piston crown would produce a similar effect. However, with worn valve stem seals, you should also observe a noticeable decrease in the engine oil level.

Black smoke ("soot") is practically always caused by a lack of air in relation to the amount of fuel being supplied under the given load conditions.

The 68 horsepower engine should have a wastegate for boost pressure regulation. Is this in place and correctly adjusted? Does this engine have an exhaust gas recirculation (EGR) system, and if so, could it be causing any of the smoke issues described?


A friend bought this T4 van (short wheelbase) about 15 years ago as a used vehicle. I had the chance to drive it a few times and found it quite sluggish, especially when accelerating on country roads or merging onto the highway. It was somewhat manageable on flat terrain. However, on trips along highways like the A9, A4, and A71, you were constantly being overtaken by trucks. Even on some inclines, it was difficult to maintain a speed of 60 km/h, even with the transmission downshifted and the accelerator fully pressed. Under load and at higher speeds, it consistently produced a visible trail of black smoke, the color of which varied depending on the situation.

Hi!

Well, I would also say,
Let's verschandeln the fuel injectors.
They should open at approximately 160 bar. And have a reasonably good spray pattern.
After all those years and kilometers, there might be some issues.

Once they're out,
Measure the compression now.

Okay, so it's workshop work.
because usually very few people have the equipment needed for it.
Check the air filter.

The rest has already been written.

Opening pressure of the 1st. The pressure is 190 bar, and at that mileage, it's a good idea to replace the nozzles anyway.

Thank you.
I'm going to rebuild the injectors and check the fuel injection start timing.
And if necessary, replace the mass airflow sensor. I have a feeling that the symptoms indicate multiple underlying issues.

I will get back to you once everything is completed.

Greetings and thank you again.

You don't need to replace the nozzles this time.
Simply replace the injector nozzle insert and adjust the nozzle opening pressure.
I highly doubt that he has an LLM.
I would rather adjust the pump's start-up timing statically if it's making too much noise.

I would start by taking the tests that are free, and then, based on the results, I would consider different solutions to the problem.

Herbert.

Tagessuppe wrote:

You don't have to replace the nozzles anymore. Simply replace the injector nozzle insert and adjust the nozzle opening pressure. I highly doubt that he has an LLM. I would rather set the start-up time of the pump statically if it makes too much noise.

Hello.

The nozzle is the nozzle insert. You probably mean that he doesn't need any new nozzle holder combinations, which is correct, and no one wrote that here. X

Unburned diesel fuel can be easily distinguished from motor oil by its smell; you can tell the difference simply by smelling the white/blue smoke.

Best regards, Rainer.