Volvo XC70 D5244T4 2008: rough idle when warm and no load
Hello, I have a manual Volvo XC70, D5244T4, 2008, 300000km with a rough idle when warm and no load. No trouble codes. After engine gets warm and i stop the car from moving, shut down the AC and lights, the engine speed varies from 670 to 730 instead of staying at 700RPM. If i switch on the AC then the idle stabilizes at 700 +/- 5RPM. If the engine is cold there is no problem with or without load. I have replaced EGR valve and actuator because even after cleaning the deposits, the valve required force to move it and the actuator was damaged and read EGR position was all over the place. Swirl flaps were exchanged and compartment cleaned of deposits. Swirl flaps were replaced because the diameter shrank from rubbing against deposits. Throttle body cleaned. MAF cleaned. Alternator swapped. Fuel pump regulator exchanged and variation in fuel pressure dropped from 3000kpa to 1000kpa. Injectors checked and are within tolerance. If i look with the diagnose tool at the graphs: the engine rpm, load_pct, maf readings fluctuate with no load, but as soon as i turn on the AC they all stabilize.
The car runs good otherwise and i also do not notice this issue often because AC is mostly on. But I know the problem is there and it kills me. I do not want to waste more money in replacing or checking random things but i do want to fix the issue as I want to keep the car.
Please help me Scotty, and of course, the rest of the community.