My girlfriend's S40 1.9 turbo has had a hesitation problem when accelerating for at least the last year. I ran a code scanner on it and it came back with a P0303, indicating a mis-fire on #3. I replaced the coil on the #3 spark plug. Now the hesitation is not as noticable, but still occurs and still throws a P0303 code. I plan on changing the plugs tomorrow. Is there anything else I should be looking at?

 

did you ever get a fix for this? Having the exact same problem on an '04 XC90 T5. Already swapped the coil and put in new plugs. Only seems to happen when cold and/or wet. Thanks!

 

Hey I have the same issue on a 04 S40 1.9 as well. Did the spark plug change fix it?

 

EDIT: Ignore what I say below. Misfire code popped back up a couple days later. My second-to-last resort was to do introduce some Seafoam directly into the Intake manifold like this: http://volvospeed.com/Repair/seafoam.html. I'll update again in a few days.

Well, I was also having the problem of my lights brightening and dimming along with the throttle position, but I seemed to have fixed that the other day by just pulling the battery terminals and cleaning them. I read in other threads about this helping with misfires. At the same time, I did an "Italian tune-up" and threw a can of Seafoam in the gas tank at the last fill-up. Car was running relatively smoother this morning, and haven't had a misfire code in a couple days.

-Joe

 

having the same issue with my 2000 S40

 

Update: Well, I finally got around to putting some "good" spark plugs in. I got Denso double platinums from Rockauto.com. This seems to have fixed the problem completely! The turbo motor definitely likes the performance plugs! I took on a Porsche 911 on I-5 yesterday! He killed me, but it was close until about 80mph then he was gone!

 

If the misfire returns though you need to replace BOTH ignition coils. I found this the hard way. Even though the trouble code lists only 1 or 2 cylinders, replace both coils.