2009 Xc70 T6 3.0 Continued MISFIRE ISSUES Need HELP PLEASE

Greetings from Maui During lock down from Covid 19. What weird times we are in right now

First thing. I'm not actually a mechanic. I'm a pro photographer acting as shade tree mechanic trying to understand what is wrong with my car when things are tight financially.

I have a 2009 Volvo XC70 T6 3.0 Turbo with a 185,000 miles on it. Had it for a long time & for a long time just brought my car to someone to fix but in recent years & have been doing work& maintence on it myself.

In the past four months the radiator, alternator & breather box when bad I replaced all. Then the thermostat whet bad & was running low temp & I ran the car with the engine light on for 165 miles like this killing the catalytic converter unfortunately.

My problems continue with this car as about 2 months ago started getting misfire code for cylinder 3 on Bluedriver. I had never changed the spark plugs so I changed all plugs with iruduim plugs (Not OEM). I also bought a a Napa non (OEM) coil & installed it on cylinder 3. Checking all the plugs they all look pretty good.

This solved the problem for a a few days.

Then another code on cylinder 3. My buddy a pro mechanic in Oregon told me to check the fuel injectors. I pulled the fuel rail & cylinder 3 had a fuel injector with no "Pittle Cap" on end & o-ring was stuck in the port of engine block. I bought a new OEM fuel injector for cylinder 3 & installed all new O-rings on both sides of all fuel injectors & reinstalled.

So I also was having a start up issue when engine was hot. I was thinking it was a bad fuel pump or bad PEM (Fuel Driver Module). I took my car to a local shop that specializes in foreign crs & they hooked my car up to their super computer testing all components. They determined that fuel pump & fuel driver (PEM) were working correctly. They suspected the throttle body, pulled it & it was filled with gunk & shit. They cleaned it up & reinstalled old throttle body. This actually fixxed the start up issue when engine is hot & now it starts every time.

This seemed to fix the problem. Car is running alright but not great & I just don't trust that it is going to hold up.


I still have P0420 Code for catalylic converter pretty mush every time I drive. But not many actual codes. HOWEVER when I check MODE 6 I get INTERMINENT indiviual misfire counts on cylinder 3 (12 or 14), sometimes cylinder 4 (4) & sometimes other cylinders including 5 & 6 sometimes 2.

I was asking my buddy about all this & he suggested maybe my battery was low voltage. I had checked this before, but last week one day car barely started. I went & tested battery & indeed it was bad so I replaced it.


Just a few days ago on startup I was listening to car & heard it stumble. I checked Bluedriver & had misfire codes for cylinder 3 & 4 but as I listened to car it was running great. I cleared codes & drove quite abit never getting any more codes, but on MODE 6 had a few random misfires on individual cylinders.

So as a novice with out alot of money I am trying to solve these issues reaching out here for any help I can get during COVID19 pandemic.

Any Ideas?

Thank you so much Tad

Is this an in-line engine or v type engine? If cylinders 3 and 4 are next to each other I’d suspect a possible head gasket leaking coolant in the cylinders.

Inline 6. Interminint Misfire happening on lots of different cylinders though

What is MAF gm/s at idle?
Give it some throttle and see if upstream stays rich.

Sounds like a clogged cat. Which the p0420 could be an indicator of.

You can pull the upper 02 out of the bunghole and take it for a drive and see if it gets better.

If you’re engine can’t push out exhaust gas fast enough it won’t be able to take in the amount of air it needs to be able to properly combust.

You really need to know the fuel pressure that you're running at and see if it is really in spec. Just like you can't always trust a new part... you can't always trust a person's words either. Low fuel pressure can cause random misfires. Also, can you look at fuel trims at all? And correct me if I'm wrong but doesn't plugged cats cause misfires? You mentioned you were getting a cat code. We get the code on our Bimmer every once in a while but you make it sound as if it's more often than this...