Exhaust Emissions at Specific RPM Range

Hello!

I'm having a problem with my Golf 3 110PS (AFN) (manufactured in 1997). The problem manifests itself as follows:

'If the engine hasn't reached 90°C yet, and I downshift from 4th to 3rd gear (with the 3rd gear around 3000 RPM), I briefly see a blue cloud behind me. Also, I tried to keep the engine speed between 2400 and 2800 RPM while stationary, because at that RPM, the car produces an incredibly strong amount of exhaust. The engine starts to vibrate noticeably, and then it's like a fog machine. The smoke isn't clearly identifiable, but it has a rather pungent diesel smell.'

The car had already been in the VW workshop for a whole week, but without success. They replaced almost everything that could be replaced – the control unit, disconnected the turbo, replaced all the fuel injectors, installed a new fuel pump, inspected the engine, replaced all the filters, changed the engine oil, performed the 90,000 km service, and conducted a compression test, and checked the error memory – all without success.

I would be very grateful for your help!

Best regards, Tom.

4 questions about it:
- How many kilometers has your engine been driven?
- What is your oil consumption per 1000 km?
- Does the coolant level in the expansion tank remain the same, or are you consuming coolant?
- Does your engine coolant temperature stay within the normal range during fast highway driving over a distance of more than 10 km?

Best regards, Rainer.

Hello Rainer!

Current mileage: 92,000 km.
Oil consumption: normal.
No coolant loss.
Temperature reading always shows a constant 90°C.

Best regards,
Thomas

Hello, what is the exact oil consumption?
If it's emitting blue-gray smoke, the initial suspicion is that some engine oil is being burned.
Is the smoke actually blue, or is it more likely black?
Are you reaching your top speed?
At which gas station did you last fill up? (Here, my TDI emits a slight gray smoke when accelerating to full throttle, but strangely, this doesn't happen when I fill up at any other brand-name gas station.)
Have you checked the error memory (fault codes) after fewer than 50 engine starts since the problem occurred?

Best regards, Rainer.

Hi.

"Significant smoke and vibrations at certain engine speeds when idling - this strongly reminds me of previous measurement attempts on the speed sensor. Apparently, simply connecting a multimeter to the sensor had corrupted the sensor signal to such an extent that a correct evaluation by the engine control unit was no longer possible."

Therefore, my tip: check everything related to the sensor - the connection, any bent wires, damaged shielding... and don't forget the trigger ring inside the engine on the crankshaft, which might have also come loose .

Hi Rainer!

Unfortunately, I can't give you an exact number. I would need to measure it myself. Based on my experience and what the workshop says, the oil consumption is very low and has already been monitored and checked. It rarely needs to be refilled, even though I drive about 25,000 km per year.

The car only emits blue smoke when it's cold and when downshifting to 3rd gear. When idling during a rev test, there's no blue or black smoke, but rather a very strong and pungent smell of diesel.

I've never gotten gas at Jet; I usually go to Esso, Avanti, or Shell.

The fault memory was not read after fewer than 50 engine starts following the occurrence of the problem.

Das mit der Höchstgeschwindigkeit geht ok. Mit Chip geht die Nadel über höchsten Tachowert hinaus. Ohne auch über 200 km/h. Alles natürlich nur Tachoangaben, also ziemlich falsch. Habe aber vor ein paar Tagen den LMM tauschen müssen, weil der Wagen samt Chiptuning nicht mehr beschleunigen wollte. Oder zumindest dauerte es bis zu 5 sek., bis der Schub einsetzte, manchmal hat sich sogar gar nix getan. Bei jedem Mal Schalten ewige Wartezeiten bis endlich der Schub wieder da war. Durch den Tausch kann ich jetzt wieder wartezeitfrei schalten und Ansprechverhalten hat sich auch stark verbesser. Ganz hat sich das Problem aber nicht lösen lassen, denn manchmal, vor allem wenn ich weitere Strecken fahre (ca. 1 h Fahrzeit), wird die Ansprechzeit des Turbos immer länger (ca. 2 - 3 sek). Könnte das auch an einer steckenden oder schwergängigen VTG liegen? Wenn ich den Wagen wieder abkühlen lasse oder zumindest eine Zeit am Stand laufen lasse, setzt der Turbo wieder sofort ein (ohne Anlaufzeiten, und ruckartig, extrem giftig). Habe auch ab und zu beim beschleunigen einen Rucker registriert, wie Schluckauf, aber kein Motoraussetzer. Passiert meistens wenn ich Drehzahl abfallen laß und dann wieder ins Gas steige. Let's get started, and let's get to work.

All in all, it's very strange. Perhaps the various additional information can help you. It would be good for me.

Thank you and...

Best regards, Tom.