My 2006 has been stalling intermittently for 6 mos or so. At first, it was accompanied by erratic idling at a light. So first things first, I replaced the plugs with OEM Volvo plugs, as it'd been two years since the last plug change. The choppy idle totally went away, the stalling did not. It happens maybe once a week or two. Or this week, it happened once a day for three days straight. It almost always happened within the first 10 mins of having left the house. I almost was able to say that it always happened with the A/C on, but this week it happened with the A/C off.

It's my wife's car so I don't drive it much. These past 6 mos have been fairly hot here in Atlanta, but I'm not sure that has anything to do with it. About 3 mos ago, after it stalled, it threw a CEL, and the code was a P303, indicating a misfire in cylinder 3. Aha!, I thought, must be a bad coil. I swapped the #3 and #4 coils, hoping it'd then throw a P304 code. It didn't.

I replaced the coils anyway, given the car has 175k miles. I also cleaned the MAF and intake. The air filter is relatively new.

Googling and researching, it looks like these areas are potential things to look into and consider, more or less in order of ease/cost, from easiest/cheapest to hardest/expensive:
1. Camshaft position sensor
2. Crankshaft position sensor
3. Fuel pump relay
4. Fuel filter
5. Fuel pump

I've looked for the relay but can't seem to find it. Also, I looked for the fuel filter under the passenger side and it's not there, so I must have a model that has it in the tank.

Any thoughts/recommendations most appreciated. Also, I have the 5 old ignition coils that I'm happy to give to whoever wants them. I know for a fact four are good, and I suspect that the #3 coil is still good too. I'd just ask that you pay for shipping.

Many thanks in advance.

 

before you blame the fuel pump, its relay or fuel filter (which was more common with 850s/V70s) consider it may be the fuel pressure sensor. If you are not seeing fuel starvation at speed, I doubt you have a pump related issue. Have you measured the fuel pressure at the rail?

Did you check around for intake air leaks - vacuum lines, air tubing/boots etc? These can be hard to find so you may need to ask a shop for a smoke test. but you can try doing a visual and perhaps spraying around with some carb cleaner (ie along seams, vaccuum line ends, trees/splitters etc) to see if anything gets sucked in and changes the idle.

I'd also add the ETM to your list of possible components. You may want to inspect the MAF and throttle body and then clean with some CRC MAF cleaner.

As to cam/crank position sensors - I assume that you have not seen any fault codes for those components so I wouldn't consider them a likely cause. My experience is there's an intake air leak or there's something up with the MAF or ETM.