Hi,

I've had my s60 for a couple months now and recently the engine has started to rev and rumble when idle but not when going a decent speed (15mph+). Sometimes on cold start it'll tumble violently and even stall but only when I first start it and am about to leave my drive way. When rumbling the lights will also flicker with the engine. I have changed the spark plugs and oil, I was thinking it might be something to do with one of the ignition coils but I'm not sure what this problem could be. Does anyone know what the issue might be?

The car has around 115k miles btw.

 

does it have a rough idle once it warms up? My sense is the flickering lights are due to the engine stumbling and turning over too slowly for the alternator to produce enough current (once the engine returns to its normal idle speed it will so the lights return). Cold start idle issues are most likely caused by a fuel mix issue - common issues include engine temp sensor being off, air intake leak (vacuum line/cracked boot etc), dirty idle air valve/throttle body/MAF sensor, exhaust leak (they can seal up once the system heats). If the idle is off even with a warm engine, then you can have a fuel pressure issue to look into as well. Has the engine produced a DTC code?

 

Hey,
Thanks for the reply it does still rumble after the car warms up but it's not as bad as cold start. I'll look into some of the stuff you mentioned tomorrow. The car does have some codes such as air pressure system failure, low air pressure in tires (not true), and engine system service required. I looked into some of the codes and figured it was due to the sensors going bad on all these systems.