White smoke at approximately 3000 RPM

Hey everyone,

Recently, I've noticed the following.

'When I rev the engine to 3000 RPM while idling, it blows out a large amount of white/blue smoke from the exhaust. Everything is fine up to 2800 RPM and above 3200 RPM, and the exhaust is clear. I think the RPM fluctuates slightly at a constant 3000 RPM (the engine jerks a little), but if so, it's only very slightly. There's no sign of this during normal driving.' I just drove 400 km with the cruise control set to 140 km/h, which is approximately 3000 RPM, and I didn't notice anything unusual.

I'm going to check the spray patterns of the nozzles now. Is this the right approach, or are there other causes and experiences related to this?

Volkswagen Golf III AFN, manufactured in October 1996, with 130,000 kilometers (approximately 80,000 miles) on the odometer, and no error codes stored.

Hello,

You're not mentioning anything about water or oil consumption, are you?
Are they okay?

Best regards, Rainer.

Sorry ,

Since everything was fine, I forgot to mention that in the excitement.

Water: No loss in the container, no hardened water hoses (due to exhaust fumes in the water).

Oil: No noticeable oil loss. Engine is dry. However, the oil level is at the upper limit (possibly 1-2 mm above). I always have difficulty checking it precisely because I don't have a perfectly level surface. I've also considered whether there might be particularly good 'splashing' of the oil in this specific RPM range (3000 RPM), which could cause the crankcase ventilation system to draw in too much. But that is just my theory.

I had the head gasket, camshaft seal, and valve stem seals replaced about 30,000 km ago.

Hmm, if the engine isn't consuming either oil or water, I'm honestly a bit at a loss.
Faulty fuel injectors should ideally only cause excessive soot buildup when the engine is warm and has good compression.

Best regards, Rainer.

Could it possibly be that the valves (in my opinion, the exhaust valves) are not closing properly? Then it should also lead to HC emissions in the exhaust, right?

Varianti wrote:

Could it possibly be that the valves (in my opinion, the exhaust valves) are not closing properly? Then, shouldn't there also be HC emissions in the exhaust?

Hi.
I don't know if that specifically creates white smoke...

However, you could try that "simple" compression test from the used car tips; it might provide some clarity.

Okay, I did it. The third nozzle is out. After 4(!) days of fiddling with a nozzle that wasn't properly secured (with 3 mm of air gap in the joint), it finally came loose. Of course, this happened right when I had lent out my tools and was planning a longer trip with my family.

Okay, I've had all the injectors tested. They should all be fine. However, the third one already has an opening pressure of 170 bar, which is beyond the wear limit. I'll leave it in for now. I also tried installing a different injector with a low-pressure nozzle, but that didn't solve the problem. I'll probably replace the entire set and then see what happens. I'm slowly starting to doubt the effectiveness of jet engines.

I'm going to start by doing a compression test, and then I'll remove the cylinder head and re-grind the valves.

I also did the Vmax test and, according to the MFA, I reached 203 km/h (the speedometer showed 212 km/h). So, I should be able to reach the stated 187 km/h, which means I should be running at full power.

Let's see, maybe I'll solve the 'Weissrauch' puzzle someday.

Hi Varianti,

Just a quick question: I also have an MFA. How can you measure the speed on that? Is it something like pressing a button, turning the ignition on, turning the ignition off, and then releasing the button?

Best regards, David.

Hi Varianti,

Quote:

I also considered whether it's possible that, specifically in this range (3000 RPM), there could be particularly good "spraying" of oil, causing too much to be drawn in through the crankcase ventilation system. But that is just my theory.

Try taking the hose off for a ride.
Then you'll know exactly!

Regards,
Thomas.

Hi Varianti,

Just a quick question: I also have an MFA. How can you measure the speed on that? Is it something like pressing a button, turning the ignition on, turning the ignition off, and then releasing the button?

Greetings, David.

No, simpler:

When driving at a constant speed, reset the MFA (Multi-Function Display). After that, your current speed will be included in the average mileage calculation. It takes about 3 seconds for it to appear.

Hi Varianti,

Try taking the hose off for a ride.
Then you'll know exactly!

Regards,
Thomas

Is there anything that could happen if I close the openings? Is there any harmful overpressure in the crankcase?

Varianti wrote:

Thomas wrote: Hi Varianti, Try taking the hose off for a ride. Then you'll know exactly! Regards, Thomas Is there anything that could happen if I close the openings? Is there any harmful overpressure in the crankcase?

Hello, "Close" = "POFF".
The blow-by gases have to go somewhere. You should only seal the opening in the intake manifold. The hose from the crankcase ventilation system should be placed in a metal can or similar, and you should make sure that nothing drips onto the turbocharger or hot parts of the exhaust system (fire hazard).

Best regards, Rainer.

So, it wasn't the case ventilation.

Since the opportunity presented itself and I had full access to a working AFN engine, I first (and after checking the injection timing) systematically replaced all the parts that could potentially be related to the engine control system. Specifically: engine control unit (ECU), turbocharger boost control valve, EGR valve, injectors, mass airflow sensor (MAF). After that, I measured the resistance of the electronic throttle potentiometer.

Result: nothing. Therefore, it must be due to the fuel injection pump. I have compared the measurement data blocks of the two vehicles again, and there were only significant differences in the injection timing ratio within the specified speed range.

So, I planned to replace the ESP the following week. As a last resort, I decided to buy the DIESELSPÜLUNG (diesel cleaner) from LiquiMoly for about 10 EUR. I'm usually quite skeptical of such 'miracle' products, so I didn't have high hopes, but still, before investing in an ESP replacement, it's worth trying a product like this for just 10 EUR. So, I did it. The packaging said that it can be mixed with 75 liters of diesel for preventative maintenance or used undiluted in severe cases. Since I was already out and about during the week, I only had 25 liters of diesel left in the tank. So, on Monday, I tipped the fuel tank over to 25 liters, drove for a while (about 30 km), and then left the car parked for 4 days. On Friday, I drove home (and refilled the tank along the way), and then, at home, I revved the engine to 2800 RPM. And lo, behold:

HE IS HEALED!!

I couldn't believe it. The engine ran incredibly smoothly in that RPM range (before, there was always a slight hesitation), and there was absolutely no more white smoke. Being as skeptical as I am, I've been observing it for the past two weeks, but the white smoke has stopped appearing.

I suspect the problem is that the injection timing was incorrect due to the fuel injector malfunctioning and providing false readings within a certain RPM range. This caused the injection to occur too late, resulting in incomplete combustion (due to insufficient temperature and pressure), and consequently, white smoke being emitted from the exhaust. The LM Diesel flush must have chemically removed the contaminants, so everything is now fine.

This isn't meant to be an advertisement for Liqui Moly, but perhaps it can be helpful for people who are experiencing similar problems and can't find a solution. The ESP now has 180,000 km on it, and it might not be a bad idea to invest in a bottle like this every 30,000 km for just 10 EUR. Because it seems that the concoction has some effect on ESP.

Can the diesel flush be used for all TDIs, including PD engines, or are there any limitations?

"In my ATD (presumably referring to a specific product or device), you can feel it in the 4th and 5th positions." The engine runs smoothly between 1000 and 1250 revolutions (RPM), but there's a slight hesitation, which disappears when accelerating gently.

In principle, it should work with all diesel engines. The packaging didn't mention anything about VP, PD, or anything like that.