Hi.
Been given a Volvo 850 Auto sedan by the wifes Godmother who at 92 doesn't drive it any more.
She bought it new in 1995 and its only done 122,000klms. Practically brand new. So very original.

Been working through some minor things.
Replaced timing belt.
New brake pads and brake fluid flushed through.
General service.
Replaced thermostat as on open road the temp guage would drop considerably.
Had all three non-driver doors fail to open from the inside and read about the little rod that falls out when the plastic breaks up and fixed them.
Replaced the crossover capacitors on the rear speakers.

But one item come to light I'd like to ask about first before I go looking into things because it might be a common problem that you guys can tell me about. The idle when in gear is a perfect 850rpm. But when put into neautral or park once the engine is warm, it sits up at around 1350rpm and doesn't seem to compensate and drop back down like most other engines. I suspect the idler solenoid if there is one but as stated, its better for me to ask first than go in blind.

Any ideas?

 

I'd suspect the engine coolant temp sensor to start with, then I'd consider checking for vacuum leaks and cleaning the idle air controller and MAF. Considering you issue with the thermostat, the ECT seems a good fit

 

Yep - Idle control solenoid sticking in a half open/half closed position.
It would open fully when activated but only close to half its working distance.
Clean and soaking in WD-40 had it sliding normally and smoothly.
Idle now stays the same in/out of gear and air on/off.
Cold engine now smooth as well - before it would be a bit shakey for the first minute or so when pulled into gear.
Easy fix too.