02 V40 Misfiring problem during acceleration

[sstoynov]

Thank you much for the detailed opinion.
So you think since it is a fuel problem - not electrical, I should not bother starting with replacing plugs, coils, cables, but rather concentrate on replacing the fuel filter and cleaning the injectors.

How do you recommend to clean the injectors? Using a Techron injector cleaner additive to the fuel, or clean them up in a shop?

[regent]

An electrical problem is possible - an intermittent common +12V supply to the injectors; in theory only IMHO. This circuit very seldom fails, and when it does it will be a 'no-start' condition rather than 'lean at load'.

I would begin at the filter and inspect all fuel lines from tank to rail for integrity.
When all that checks good, my next step would be running some injector cleaner (I've successfully used Seafoam - 1oz to the Gallon of gas - added to the tank, but it is up to you to use the Techron stuff)

The above described is the least expensive path and I hope it solves your 'miss'.

If it doesnt, then you will need to see by how much your fuel pressure fluctuates (min/max values, etc.) to rule out the FP and FPR before taking the injectors to a shop. You can search the forums for info on rebuilt injector kits on eBay (I think I saw a post recently) in case you need to go that way or have them cleaned in a shop.

[sstoynov]

Update to my issue: replaced the fuel filter - no change. The check engine light came on and I managed to capture a freeze frame - here are the details:
Freeze frame information:
------------------
Fuel Status = 0 byte
Engine Load = 91.765 %
Engine Coolant Temperature = 62 °C
Fuel Trim Bank 1 Short Term = 11.719 %
Fuel Trim Bank 1 Long Term = 2.344 %
Intake Manifold Pressure = 19 psi
Engine RPM = 3,845 rpm
Speed (OBD) = 55 km/h
End of report.

I know I have to replace the Fuel Pressure Regulator(i've done it once before - 20-30k miles ago with one from a junk yard - new ones cost fortune), cause it takes a while the car to start, but I am not sure that could cause the issue.

[regent]

A bad FPR could do that but I am thinking more likely an obstructed flow that will cause drop in pressure at higher volume (think about a crushed, bent, or pinched line or a kinked hose)
At this stage I'd do a good visual inspection - the whole nine yards - and then go for the FPR

[sstoynov]

Changed the plugs with orig. Volvo ones and everything is resolved... can;t believe it...

[regent]

Glad you sorted it. Indeed, I thought you were running 'lean' on acceleration - almost forgot our cars are somewhat 'picky' on plugs.