My S80 has developed rough idle when engine is hot and only when hot. Engine is very quiet and steady when cold and has absolutely no indication that anything is wrong. Car also pulls with no problem (hot or cold), power is there when you need it and floor it. Fuel consumption is normal and also there's no smoke whatsoever. There is some smoke smell in the cabin though, but only when engine is hot. I don't know if this is somehow connected to other two issues I have:
- RPMs start to fluctuate when coming to a stop (breaking or cruising - a bit more evident when breaking). Engine won't stall, but it definitely drops significantly. But as soon as I stop this big fluctuation stops, but then that rough idle comes in. This is not happening if I step on a clutch (coming to a stop breaking). As soon as I release the clutch, RPMs start to fluctuate (coming to a stop breaking). This problem is regardless of the engine temperature.
- When car sits for a while (let's say 8hrs) it starts "weirdly". It turns over but it will hang on 700 RPM for a few seconds and after that it will jump to > 1000 RPMs. Meanwhile nothing electrical is working (no lights, gas pedal not responsive, no radio, no fuel capacity level, ...). I can also hear that in this short time the RPMs are slowly rising and after that RPM jumps again to a 1000 RPMs. So it's something like: first stage fast rising to 700 then second stage slowly rising to 700-710ish and the last stage fast rise to 1000. This is only happening sometimes, but a lot more often lately. Please see the video below.
These two problems were already present when I got the car on 01.10.2019 @298.000km.
Rough idle dissapears when I turn on the AC, as the engine gets more load. Other two problems are not affected by the AC.
Service history (chronologically):
- Oil and oil filter changes are made on 10.000-13.000km interval w/ Castrol Edge 0w30 A5 and OEM or MANN filter
- Fuel filter 10.10.2019 (FRAM) 298.000km
- MAP sensor (Bosch) 11.12.2020 @333.000km
- Cleaned Throttle body 11.12.2020 @333.000km (also changed the gasket)
- Fuel filter 23.03.2021 (OEM) 340.000km
- Air filter 23.03.2021 (OEM) @340.000km
-
Rough idle started 17.08.2021 @353.000km
- EGR clean (not thoroughly, only what I could manage to scrape out) 05.12.2021 @360.000
- Fuel filter 25.02.2022 (MANN) @367.000km
VIDA shows no trouble codes.
I'll be more than happy to fetch you more data if you'll need it.
Attached:
- First two videos show that "weird" start, the third video shows that RPM fluctuations when breaking and rough idle (at the end of the video). This one is a bit shaky - I'm sorry for that, I can also try to record a better video. Also please turn up the volume at the end of the video (on this third one) to hear that rough idle. The last video is just idle engine (cold).
- Images from Vida showing different parameters. This was recorded when engine is hot. Interesting is that one image showing injectors (one having a 39 r/min difference is quite big, right?).
- Image of inside of EGR valve after cleaning
Car:
Volvo s80 2.4D D5244T5 M66 my2009
Weird start #1:
Weird start #2:
RPM fluctuations and rough idle:
Engine idle (cold - so the IDLE is fine. ther's some popping noise tho):