I doubt it's the FPR, as a previous poster indicated a faulty FPR will give you different symptoms than what you've described and may have you stalling.

Just for the hell of it - switch the sparkplugs up and see if you get an error on a different cylinder. My understanding is that these cars are very finicky with sparkplugs - but could be different for you model.

Faulty fuel injector seems like a bit of a long shot to me but possible (and expensive). I'd be inclined to do some more research or bring the car in before going there.

 

Yeah, you might be right....But the fact that they're new plugs makes me doubt it....But what the heck, I'll either do the switcheroo like you suggest, or just run out and buy a new plug (Bosch FGR6NQE0...same as Volvo dealer's), slap it into #2 and see if the CEL's go - and stay - away.

Funny thing, a co-worker with a Honda had a similar problem: same "0300" series codes popping up...replaced a bunch of parts along the way...ended up going to a mechanic (the guys who happen to do most of the work on my S40, by odd coincidence)...they figured it out immediately: poor compression in the affected cylinder.....So, like you say, possibly not a FPR/FPS/FI issue, and maybe just a bad (new?) plug...But I will stop by Harbor Freight tonight to pick up a compression tester for about $25 (Should have this on-hand anyway)...Thanks for the suggestion.

 

Fuel injectors are pretty bulletproof these days. When my 2005 lost power power for a few seconds it turned out to be the fuel pressure sensor. The 2004.5 and up 2.4L and 2.5L engines do not have a traditional FPR like the 2000-2004 1.9L turbo engine. The newer motors have a fuel pressure sensor mounted to the fuel rail that causes the fuel pump to vary pump output by varying the voltage to the pump. Seems overly complicated but it works.

 

...which is why I bought the (nicely low priced, but older version) FPS from Rock Auto, and will probably plop it in this weekend or the next.

Just for sh%ts and giggles, I picked up some "Dura Lube Severe Fuel System Cleaner" in the AM, and threw it in just before getting to work...so it had the day to sit and mix in with the gas. Got in the car in the PM, started up great, car ran noticeably quicker, very smooth at 6000RPM+/-, no jerking around. (I work in PA / live in NJ, so it's a good 40min commute). Went out in the evening, and it still ran smooth as silk, no CEL's...I thought "Wow, a $10 solution really worked here!", while I was preparing myself to drop a lot more $...But, this morning, same nonsense: CEL flashed, flashing red "slow down or shift up" popped up...CEL then stayed on, code P0302 (OBDII reader now sits at the ready under my seat, ready to whip out/connect/read/erase)

So maybe I was on the right track: that it just needs a really good "cleaning"....FPS is still on the agenda (as well as maybe a compression check)...But before I consider talking to my mechanic about a more thorough cleaning with the really nastier ($) stuff, I might just try one more over-the-counter "miracle in a bottle".....I've read some great things about "Seafoam" on other enthusiast sites, several cases where it cleared up the ominous "P0300" series codes....Anybody among the Volvo gang have any experience with this stuff?

 

Seafoam makes for a good smoke show out the exhaust when you pull it in through a vacuum port. Through the vacuum port cleans the carbon off the pistons. In the fuel cleans the injectors too. Careful you don't hydrolock the cylinders by using too much too fast. It does not evaporate like gasoline.

I would not use it in the oil for more than a few miles. It tends to loosen any gunk which ends up in the filter quickly.