Hey guys, I don't know if this is an issue or not, but sometimes when I shut my car off, there seems to be a hesitation to power off. Almost like a misfire? My S60 is almost up on warranty and I'm wondering if I should get this checked. My fuel pump was replaced a few thousand miles ago, and now my car starts right up all the time. Just doesn't shut right off all the time. Not that it lasts for several seconds, it doesn't. But you do notice an extra compression or two sometimes. It's a 2013 S60 T5 I'm up to 45,000 miles.

 

Many years ago it wasn't unusual for a gasoline engine to do that. In fact in the worst case the engine wouldn't shut off at all but just keep clattering along. To shut it off you'd have to put the car in gear (manual trans) and drop the clutch with your foot on the brake.

I'm not saying this is your problem but the cause back then was hot spots in the combustion chambers typically caused by carbon deposits.

So...how long have you owned the car?...do you use a high quality synthetic engine oil?...how often do you change the oil?...do you regularly put any kind of snake oil in the gas tank?

 

Thanks for the idea of carbon build-up. I bought the car last summer with 32,000 miles on it, dealer told me it only had one owner previous, but that one owner was a car rental. I usually only use one brand of gas at Costco, I bring car to dealership for synthetic oil changes, and and any other discrepancies.

 

Modern cars aren't very susceptible to dieseling but as your car is a former rental it's worth considering. Your car may have had as few as zero oil changes in 32,000 miles.

Your engine is a good candidate for some kind of snake oil treatment. The two snake oils I think may actually work are Techron and Auto-Rx. I've used both. SeaFoam is another but that process always seemed wrong to me.

 

My car has had all of its scheduled services. I think their are like 4 factory services that Volvo offers for the first 32,000 miles. I am familiar with Techron, I used it in my '01 S40 and it helped quiet it down. I also think Volvo adds some kind of fuel treatment during these service intervals?