Skoda Octavia 1.6 TDI DDYA - Misfires/Jerking during cold start

Dear forum community!

Since I'm running out of ideas, I'm hoping you can help me.

The vehicle mentioned above, a 2017 model with 116 horsepower, has approximately 130,000 kilometers (or about 80,000 miles) on the odometer.

For approximately 1000 km, it has been noticeable that the car jerks, misfires, and has poor acceleration during "cold starts" (even when the nighttime temperature is as low as 16 degrees Celsius).

The phenomenon lasts for about 1-2 minutes if you start driving carefully, and then it disappears completely – at least, nothing is noticeable anymore.

The car then has normal performance (as expected), doesn't consume more energy than usual, doesn't regenerate energy more frequently, and also doesn't have any error codes related to this issue.

The only noticeable thing was that the oil level had increased before the last oil change, so it's highly likely that there was diesel fuel in the oil.

The vehicle is currently used mostly for short trips, but it also has longer highway journeys about 2-4 times per month, covering approximately 300 km each way.

So far, there have been no motor-related problems, except for a damage caused by a rodent.

What have I already done?

Spark plugs replaced (BorgWarner), including labor. Pressure probe.
Diesel filter replaced (lastly at 88,000 miles/kilometers).
Quantity reconciliation via VCDS.
Injector return flow measured.

It's noticeable that the amount of oil leaking from the injectors varies among the four injectors. The cylinder with the largest leakage is cylinder 1, which is the most significant outlier.

Here's another picture of the measurement (from left to right, the cylinders are arranged from left to right when you're standing in front of the car). The measurement ran for approximately 6 minutes, 5 of which were at idle, and 1 minute at the rev-limited speed while stationary (so around 2500 RPM or something).

As far as I can tell, there's likely a leak inside the injector, probably into the combustion chamber.

When the engine is warm, any leakage from the injectors stops.

Are there permissible leakage amounts? Are all 4 injectors showing unusual behavior?

I look forward to hearing your valued opinions - thank you!

Best regards, Alex.

Hello,

I would check the injector timing.

Comparison values may be found here.
Okay, I understand. Please provide the German text you want me to translate into English. I will only provide the translation.

Then, consider the control behavior of the EGR (Exhaust Gas Recirculation) system and the fuel rail pressure. For both, you have a target value and an actual value. If the control behavior is erratic or if there are persistent differences between the target and actual values, I would investigate the EGR valve or the fuel rail pressure control valve more closely.

Quote:

"Cold start" (even at a minimum of 16 degrees Celsius at night), it jerks, misfires, and the throttle response is poor.

If the above checks are normal, there is still a possibility that the engine control unit (ECU) is experiencing power supply issues.
In this case, I would use VCDS to log the above data during a cold start.
If you're experiencing "stuttering" or unexplained interruptions and pauses, I would investigate the power supply area, specifically the engine control unit and, in general, the entire wiring harness (looking for damage or chafing).

Generally, it's a good idea to carefully inspect the wiring harness and check the connections at the relevant sensors.

Best regards, Rainer.

Hello Alex,

There were problems with the high-pressure pumps in the engines.

What is the pressure rating of the high-pressure pump?

Index K has announced the imminent "end" of its operations, citing the problems you described.

Have you ever checked the amount of material returned by the magnetic separator to see if it's mostly chips?

If you can rule that out, you can continue using the injectors. The return flow should be approximately the same.

Perhaps you can still save the nozzles with a fuel injector cleaning treatment.

Best regards,

Michael.

Hello!

Okay, as far as I can see, the pump has the "H" designation. I should be able to check the metal part in the filter tomorrow; I've kept it aside.

I can't find the injector timing values in the measured data, and it's also not clearly indicated whether the data relates to the EGR valve or the fuel rail pressure valve. Is there a specific name or IDE number for that?

Regarding the pressure and rail pressure control valve, isn't it strange that the symptoms disappear when the engine is warm?

Thank you very much!

Best regards, Alex.

Hello,

There are a lot of extended measurement values available. I recommend using the search field in VCDS. Okay, so terms like AGR, EGR, pressure, and druck would be search terms.

If you have found them, you could also post them in this topic.
Okay, I'm ready. Please provide the German text you want me to translate.

Best regards, Rainer.

dieselschrauber wrote:

Hello, There are a lot of extended measurement values available. I recommend using the search field in VCDS. Okay, so terms like AGR, EGR, pressure, and druck would be search terms. If you have found them, you could also post them in this topic. Okay, I'm ready. Please provide the German text you want me to translate. Best regards, Rainer

I will search again - I have already tried using the search function.

Thank you very much!

Best regards, Alex.

Hello Dr. Zikzak.

My Skoda Octavia has exactly the problem you described. Interestingly, it started for me as well with almost 130,000 km on the odometer.

Have you figured out how to fix the problem?


I would greatly appreciate a brief response.

Best regards,
Matthias.

Hi,
Could you please provide us with an initial car scan?
And then a clearer problem description from your side? The topic of Doc Ziczak is one year old and doesn't necessarily have to align with yours.
hg
Herbert.