Hello everyone. Please comment on my strange symptoms of my Volvo.
This is 2012 V70 T5 2.0 B4204T 6DCT 110k miles.
The problem seems to be that the engine has misfired at irregular timings since it warmed up.

[Symptoms]
・ The engine is warm. About after running 10km (or 15 minutes).
・ Load on the engine. Step on the uphill or accelerator.
・ Vibration as if stepping on a narrow seam on the road. Misfire. The rotation goes up and down about 200 rpm.

【Current status】
・ There are no error codes and messages.
・ No symptoms appear in the morning or when the engine is cold.
・ No symptoms appear even if I stop and rev.
・ No symptom appears when the accelerator pedal is kept constant.
・ There are 2 sets of 4 plugs, 4 IG coils, and 2 sets of MAF sensors, so I tried to replace them.
・ The DCT is replaced with a new one.

【Predict】
・ Plug leak (I tried 4 NGK and 4 Ford, but the root seems a little brown)
・ High-pressure fuel pump (Failure product arrives and is replaced)
・ Injector clogging

Which one do you think? Have you ever seen such a symptom?
thank you for reading. Nice to meet you.

 

It was the transmission oil. sparse or dirty.
When I changed the DCT oil and oil filter, things got better.

I am the cause of everything.
I didn't know that a misfire error would appear if there was a problem with the transmission oil. Lack of knowledge.

I'm writing this here in hopes that it will help someone find a solution. Thank you.

 

Have you checked the ignition coils?

Sure, usually they give the error code but not always.