2007 Volvo S40 running poorly

ssracer18 · Post by **ssracer18** » 20 Nov 2018, 21:32

My 2007 S40 runs horrible in the morning when first started up. It idles very rough, sounds horrible and has a shaking/vibration when in drive, and foot on brake (at stops), lack of power and is getting lousy gas mileage. No code has been thrown. We have replaced the ignition coils, spark plugs, air filter and intake O-rings. We have added Techron cleaner to a tank of gas and we have cleaned out the throttle body. Nothing is helping. We did the lay-mans test on the injectors (all have same Ohm reading, and all sound the same when the engine is running). As the car warms up (30 minute drive to work), the severity of the symptoms lessens. After being at work for 8-9 hours, when the car is started up in the early evening, the issue is there but not as bad as it is in the morning. The car has 200,000 miles on it so it is not worth paying the high price that is charged in this area to have it looked at (besides we already took it in and had it put on a scope with no results)

jtopiso · Post by **jtopiso** » 21 Nov 2018, 02:14

I don't know on these volvos, but some audis can do that when an engine coolant temperature sensor gives a bad signal: you get no codes, but bad A/F mixture when cold.

Try looking for all the temp sensors on the car, and try to disconect them one by one to see what happens and you might get a lead on the problem.

ssracer18 · Post by **ssracer18** » 22 Nov 2018, 10:05

We just did another "test" where we put a latex glove around the oil filler hole with a rubber band around it and then started up the engine, and the glove blew up fast like a balloon - almost popped. If I remember from all my searches, this means a bad PCV, but my car does not have a separate PCV - mine is not the turbo.

So, what does it mean with the air pressure coming out of the oil filler housing?

200HPCars · Post by **200HPCars** » 08 Jan 2019, 14:31

jtopiso wrote: ↑21 Nov 2018, 02:14 I don't know on these volvos, but some audis can do that when an engine coolant temperature sensor gives a bad signal: you get no codes, but bad A/F mixture when cold.

Try looking for all the temp sensors on the car, and try to disconect them one by one to see what happens and you might get a lead on the problem.

I believe this is a good suggestion, i just changed the thermostat and engine coolant sensor in my 06 s40 t5 i feel the difference immediately my car is back to being fun to drive