Hey everybody,
This is my first post, and I am aware that there might be an answer of some kind already on the forums, but please forgive me since I tried looking for it, but It really did not come to any success. If anybody have any relevant threads, please do not hesitate to leave them below.

Now to the point.
Basically I recently bought myself a Volvo S60 from the 2001 it is a 2.4i the non turbo variant with 140hp. And the engine is acting weird. Explaining it in detail, the engine when it is cold, for example in the morning when commuting to work and the engine has not heated up to the optimal temperature it drives fine, but when it reaches the optimal temperature on the dash, the revs start to act funky, for example when breaking in front of the stop sign or a red light, the revs drop really low and the car almost stalls, another example is when the wheel is turned to a full lock while lets say parking or doing something in the low rev range, the revs also drop really low ~400-600 range, which sometimes stalls the car which is quite annoying and of course requires fixing. But I do not have any idea where should I start, I've recently replaced the spark plugs (because they were in need of changing), but that did not help the situation at all. Also when the engine is already at the optimal temperature, just idling while parked, the revs jump around a lot, mostly when the air conditioning is on. So yeah..

That is what is happening that I could say at the top of my head, I really enjoy the car since it is one of the most comfortable cars I have had, and I do not really want to sell it or scrap it.

This forum was the last place I thought of asking about this issue before going to a mechanic. If you have experienced this and some how solved the issue, I would be really appreciative for the responses, hope you are having fun with your Volvos and I will wait for your replies, thank you in advance.

 

My first thought would be to replace the engine coolant temp sensor located under the thermostat housing. I'd suggest doing the ECT sensor, thermostat and coolant overflow reservoir cap as maintenance items at the same time. Figure $100 US total in parts and maybe a new socket/spanner to grab the sensor. A shop should be able to do this with 1 hour of labor and shouldn't need to drain the radiator.

 

Your first step would be to scan the car with an appropriate scanner and see what codes are there. If any are present - that might give you a start of a reasonable diagnostic process. (guess, replace, pray it's fixed, and check is not a reasonable process, and can be quite unnecessarily expensive.)

Your 2001 has the Magnetti maerelli (sp) throttle module. Those are well known to fail, and cause all sorts of running problems. Do you have any idea how old your throttle module is? Some more knowledgeable know about yellow or white stickers indicating whether it's been replaced.

The throttle can be quite expensive - a company such as xemodex offers a great upgraded product. If you do end up replacing the throttle - be aware that the module is coded to the VIN of your car - you can't just bolt another one on and have it run. (there are exceptions)

 

Might just be a bad/dirty IACV? (Idle Air Control Valve) <shrug> I don't know much yet about Volvos, but I think most/all cars have them, and those symptoms sound related. But like hoonk says, check for codes first, don't go guessing. Many malfunctioning parts/systems can exhibit the same/similar symptoms.

 

The drive by wire throttles beginning with most Volvos in 1999 do not have a separate idle motor/iac/whatever you want to call it.

 

I didn't realize they went to drive by wire that long ago, that's pretty impressive. Subarus were at least 5 years after that.