Hello I'm wondering if anyone out there can give me some insight on this issue. 2005 S40 T5 137k miles starts up and runs great but when you "get on the gas" like to pass someone the car revs up and accelerates but then cuts out power. The strangest thing is after this event I am pressing the gas pedal halfway down or more sometimes and it is very very slow but then revs to 4k you can trick it to shift by feathering the gas. Once car is shutoff for a few hours everything is back to normal with acceleration but once you open it up (more than normal driving) it cuts out and starts being very slow. Already replaced fuel pressure switch which has helped and is noticeable but it is still happening .No CELs or warnings either. Any help would be great thanks.

 

I'd be suspicious of a fuel pressure issue - possibly fuel pump or tank vent issue. Does it run better/worse with a full tank of gas vs empty?

 

I have experienced this both with full tank and close to empty. It's strange because it seems to rev up fine but then cuts out very quickly and smoothly while driving no knocks or jolts. Also when in neutral you can rev it up just fine engine sounds strong. But while driving after you get on the gas like to pass someone it cuts out and then starts being slow.

 

Sounds like the knock sensor pulling timing to prevent engine damage. You running premium, regular, have strange winter fuel additives from the government?

 

I am running premium don't know what the previous owner was doing. But thanks to you guys I can now investigate some things. I'll be sure too keep and up to date report. Thanks everyone and if you've had this problem before let me know your experience as well.

 

have you scanned for codes to see if anything is stored? (does the CEL light come on during the start up bulb test sequence?)

 

Haven't scanned yet but the cel light does illuminate when going through key positions before start but not while running. I'll hook it up later today just in case. I am also keeping a log now of amount of gas I have in the tank and weather (maybe unessasary) but drove home last night and all was fine. Ah they joys of troubleshooting. I'll update later if any CELs are found or have been stored.

 

Update:
​​​​​​Plugged scanner in and found no faults/codes. Also took beauty cover off and inspected wires for coils some of the plastic shielding was missing but no exposed wires or breaks. Next used an old trick and listened to the injectors using a long screwdriver pressed to ear. They all sound ok. Last thing on my list is to check fuel pressure at rail (not done yet). Also do I have a fuel filter outside of my tank? I have been seeing mixed answers with that for my 05. Will update along the way with any new news. Thanks

 

Is yours 2WD or AWD? Tasca shows two different part number for the external fuel filter 2WD is #8621294 but you need to check your chassis number for correct fitment. To confirm your model has a serviceable fuel filter, just go under the car and look - there should be a round canister (maybe 3 inches round x 3-4 inches long) in the rear in front of the gas tank. Dunno if its on the left or right on your car.

 

Could it possibly be vvt solenoids? Just throwing it out there in theory it makes sense.

 

That's one of a couple hundred possibilities. I wouldn't recommend trying to buy your way through the whole list though.... ;-)

Never had a VVT problem with my Volvo, but just replaced both VANOS solenoids (BMW's version of VVT) - but my car was also throwing codes relating to valve timing (and they were at the age where they fail VERY regularly, too).

If you had the Torque Pro app on an Android phone with the appropriate Bluetooth OBD "dongle", you could monitor lots of parameters that would likely help you figure out what's not quite right (like vacuum, spark advance, fuel pressure, O2 sensor info, etc., etc., etc.). If you have a different style phone, there are similar apps and OBD adapters that will work (though they're usually pricier than the $20 or so total (!) you'll spend for the app and dongle for a 'droid phone).

 

Your model Volvo has a fuel pressure sensor on the end of the fuel rail. This replaces the mechanical fuel pressure regulator on the older models. Fuel pressure is regulated with changes in voltage sent to the fuel pump. When mine went bad it did give an error message on the info screen on the dash. However, it did not set the check engine light. Did you see anything like "reduced engine performance"?

 

Update:
First I want to thank everyone for the input on my issue. The issue is solved!! It ended up being a combination of the FPS and some really poor transmission fluid. I did a drain an fill on the trans ended up replacing about 5 qts with new fluid. The vehicle now is running a whole lot better with the FPS and now shifting problems have come to an end. Again thanks to everyone for their input and I hope this info can help future problem DIY ers.