2007 Volvo S40 T5

First thing you need to do is clear the codes and run it again. If you already swapped the #2 coil, you'll need to actually swap the injector to another cylinder just like the coil to properly diagnose that. However, I don't know that it's your issue. You mentioned that you used two different brand iridium plugs... these cars are pretty sensitive to spark plugs. You need to use the correct ones, nothing "better" and certainly nothing lower end. The correct spark plug your this car is Volvo part number 30751806. These can be substituted with Bosch FR7MPP10 gapped at 0.027".

The codes were all pending codes and engine light flashing on and off. I cleared the codes. The first set of irridiums were autolites, and drove fine with them for the last 10K. Now to try to find the problem i put in NGK irridiums but that doesnt fix it. The thing i dont understand is why it starts with no miss until revved up to 2500, then miss doesnt go away til you shut the car off and restart it. Then the miss is gone til you rev up again. It will not miss if you keep it under 2500 all day.

That's weird... are you sure there aren't any other codes? It would be worth checking fuel pressure as well.

Fuel pressure is 46 psi. Volvo spark plugs make no difference, nor do all new coils . Scan while driving shows 2 thru 5 have 3500-3700 misses in a 65000 cycle. #1 shows no misses. Compression ranges from 100-125 psi. Still only misses after 2500rpm and then misses til you shut it off or clear codes. Then won't miss again til you take it above 2500 rpm. Not sure what to do??

I can erase the code while driving at any rpm and the engine smoothes right out for 30 or so seconds then starts to miss again until I erase the codes or shut off and restart.

Try cleaning your MAF sensor. It could also be your crank or cam sensors, but I would start with the MAF. Another thing you can do it unplug your MAF sensor, then start the car. Any of those things could potentially cause a multi-cylinder misfire like you're experiencing.

I have cleaned the MAF sensor and I have tried unplugging it. Makes no difference. Again it idles perfect until I rev it up to abot 2500 rpm then miss is there even back down at idle until I clear the code or shut off and restart. When I get to 2500 ish the check engine light flashes and the codes are 0300, 0302,0303,0304,0305 but never 0301 for cylinder #1 in the codes.

Just out of curiosity, have you done a compression test? I don't know that low compression would be a problem if it doesn't start misfiring until it's over 2,500 RPM, but it's good to cover all your bases. Another common issue on these cars that might cause a misfire is the fuel pressure sensor.

Thanks for the replies. Yes I did compression although did compression cold but realize now it should've been done hot All on the low side 100 to 120 but done after sitting for 2 months so probably not accurate. It still pulls strong til the miss starts and will idle to 2500 all day long and not miss. I will order a fuel pressure sensor.

The numbers may seem low, but gauge accuracy can vary, and engine temperature and other factors may affect the numbers. The important part is that all 5 cylinders showed similar readings and there wasn’t a large range. I think that fuel pressure sensor may be your problem. It’s a common failure that will cause random misfires like this.

I replaced the fuel pressure sensor with a new Bosch OE unit. Makes no difference. If I erase the misfire codes it runs perfect up until 2500 rpm then if I hold it at 2500 or higher and erase codes the miss will go away for 10-12 seconds and come back til I erase the codes again.

My only other suggestion is to replace the crank and cam position sensors. But I don’t like to just throw parts at problems without testing. I highly recommend posting a thread over on Swedespeed.com in the S40/V50 section, someone over there should be able to help more.