My 2004 Volvo S40 2.4i said "pull over or shift down" and was shaking violently about 3 months ago so I took it to AutoZone and they told me to replace the spark plugs and cylinder 5 ignition coil pack, and then it ran fine. Lately it's been feeling like it has a loss of power, and then on my way home it dropped in RPMs and the engine died. The dash and radio was still on. I turned it off and it wouldn't start, but tried it again and it did. It smelled like burnt oil, bad. I had to give it gas to keep it alive and now I have no idea what to do. Do I just swap the pack again? Is there a sensor going bad? Timing chain? Please help!!!!

 

Did you happen to notice if the engine was hot when you pulled over? It's clear that the problem isn't a coil pack - the engine will lose a little power and idle rough, but it'll still start and won't smell like it's melting.

From all indications, the engine was VERY hot when you pulled over (that's why it wouldn't re-start).

If it wasn't hot, you could be smelling bits of the timing belt burning (I've seen belts come apart and bits can get jammed in all sorts of interesting places). If this is the case, AND you're really lucky, the timing didn't move enough to cause your valves to contact your pistons. Then it's just a matter of replacing the belt (and water pump and tensioners). If the valves DID get into the pistons... a new engine, or at the very least, a costly head refurb is in order.

 

Did you check the oil and coolant levels - any sign of excessive consumption? Any sign of oil dripping onto hot engine parts?

 

I drove it a little today, about a mile, trying to get home but eventually pulled over and had it towed. The oil was black and orange, like it had been mixing with the coolant. It did have a rough idle and loss of power, but now it's worse. Im gonna tear down the engine and check the headers and block. The engine overheated while I was driving.

 

Sounds like a blown head gasket. How much damage was done depends on how hot it got (and how lucky you are). Not a trivial job, but one that is mainly within the sphere of DIY - pretty much a timing belt change with a head removal / reinstall thrown in, and a trip to your local machine shop.