2000 volvo S-40 rough idle

2318022 · Post by **2318022** » 06 Dec 2012, 08:07

My 2000 Volvo S-40, when starting in cold weather, will not idle. I have to feather the throttle to keep it running. When the temperature is warm there is no problem. I have changed the Idle Control Valve, Mass Air Flow Sensor with "new" Volvo parts and cleaned the throttle plate. Does the O2 sensors have anything to do with the idle at cold temperatures?

ChaddGostas · Post by **ChaddGostas** » 06 Dec 2012, 08:17

I'm gonna take a stab and ask if you have changed the fuel filter lately. Is there a throttle position sensor?

Post by **zulu-v40** » 06 Dec 2012, 10:35

The fuel filter is located on the driver's side just before the rear left tire. There is a quick release on the fuel line that is tricky to release. I did so with a pair of small scissors. There is a TPS fixed to the underside of the throttle body.The throttle body has to be removed in order to access the TPS.

My suggestion is to check the spark plugs, spark plug wire set, and engine coil packs for faults. Replace with OEM parts if faulty. Also, I would search for vacuum leaks. If you've got more than 100,000 miles on the odometer, you might search for vacuum leaks around the intake and exhaust manifolds.

Another thing to consider is that maybe the computer did not 'accept' the new MAF sensor. Perhaps the readings are so different from what the computer has become accustomed to that the air ratio is less than optimal. You might try disconnecting the battery for a while and seeing if that clears up the problem. I wouldn't rule out the MAF as your problem just yet. Maybe go back over your work too?