TDI 1.9 Engine: Stalling, Surging, or Running Rough?

Hello!

Help!! My engine occasionally surges briefly on its own. When I'm coasting in gear or driving slowly, the engine will suddenly accelerate for a short period. At that moment, the instantaneous fuel consumption display also briefly shows a consumption (0.5 - 0.6 liters). This happens whether the engine is cold or warm, at different RPMs, and even when I'm braking. I've also experienced the engine revving up briefly without me pressing the accelerator 2 or 3 times during startup.

Best regards, Arne.

zecke24 wrote:

When I let the car roll in gear or when I drive slowly with little gas, the engine briefly accelerates occasionally.

At that moment, the instantaneous fuel consumption display also briefly shows a consumption value (0.5 - 0.6 l).

Quote:

Hi, It's normal near the idle speed: TDIs resist the initial stalling.

The engine makes it both cold and warm, and at different speeds .
What was the maximum }revolutions per minute (RPM) at which you observed this?
The idle speed is slightly higher when the engine is cold.
If the vehicle has electronic load management, the increased engine speed can also help maintain a sufficient voltage in the vehicle's electrical system.

I had a problem with a Passat PD where, after starting the engine when it was cold, the engine would rev up to approximately 2500 RPM without anyone pressing the accelerator.

The coolant temperature sensor was broken in my car.

Hello!

The maximum speed was approximately 2700 RPM.
'High-speed operation' doesn't mean the speed increases like it does during acceleration.
The entire process takes less than a second, and during that moment, the car accelerates more than I could if I slammed the accelerator pedal down briefly.
The car suddenly surges forward for a very brief moment, but only momentarily, and without me changing the position of the accelerator pedal.

Best regards, Arne.

What kind of engine is this, actually?

Hello.

A 1.9 TDI PD engine with 130 horsepower, model code AVF.

(As stated in the title)

Best regards, Arne.

zecke24 wrote:

The highest speed was approximately 2700 RPM. "High-speed operation" doesn't mean the speed increases like it does during acceleration. The entire process takes less than a second, and during that moment, the car accelerates more than I could if I slammed the accelerator pedal down briefly. The car makes a noticeable push forward at that moment, but it's only for a very short time and without me changing the position of the accelerator pedal.

Hmm, that's significantly more than the usual procedures I was referring to... something else is wrong!

I can definitely see the idea of using a water dispenser with "chli." However, if that were the case, there should also be something in the error log, unless the automatic clearing function has already kicked in due to the long intervals.

I think I've experienced similar symptoms before, but quite rarely.
For example, in my case, it happens when using the cruise control – not when it's running at a constant speed or making extreme adjustments, but simply when it needs to maintain the fuel injection in a certain way. Then, it sometimes happens that the engine suddenly accelerates much faster than I could ever command with the accelerator pedal, both in terms of responsiveness and intensity – as I said, it's brief and extremely strong. But what is ?


By the way, almost the same engine ARL.

It's definitely the coolant temperature sensor.
(4-pole, green)

I can only confirm. The symptoms are quite clear.
Sometimes, the error code doesn't appear in the error memory right away.

Regards,

Olaf.

Do you think the same might be happening with mine? Are you sure it's the sensor itself? Or what I suspect is a contact problem somewhere that occurs intermittently. Otherwise, the reported coolant temperature in VAG-COM seems perfectly fine.

Hello!

Could it really just be the temperature sensor? I also experience this problem during engine cutoff (when braking and when coasting with the gear engaged).

Best regards, Arne.

Hard to believe, but:
Yes, it could be the temperature sensor.
No, it's not a loose connection outside the sensor (e.g., a connector).
I've been trying to figure out the cause of these symptoms myself for quite some time.
Ultimately, the temperature sensor can fail in various ways, as it essentially contains two sensors in one, which is why it has four pins.

1. Both donors are crazy.
2. The sensor for the instrument cluster is malfunctioning, but the engine is running normally.
3. The one for the engine control unit is malfunctioning, but the instrument cluster is displaying the correct information.

Case 3 is most likely to occur here.

Regards,
Olaf.

Hello!

I replaced the sensor. Unfortunately, the described symptoms are still present.

Best regards, Arne.

I'm experiencing a similar problem with my AV fistula.

Occasionally, the engine would rev itself up during startup, immediately reaching approximately 2500 RPM.
Then, very slowly, adjust to 860.

In the error memory, I had an error related to the coolant temperature sensor. I replaced the sensor, and the problem is gone.