07 Q7 with 4.2 HEEELP!!
 

Ok, around a month ago I started noticing no power from a dead stop when accelerating. I can almost put the peddle to the floor and its barley moving, but when I go ahead and push it almost to the floor, it will kick in full throttle. Very noticeable to passengers like I want to go really slow and then stomp on it. It does this about 50% of the time.

The engine light came on, it ended up being a bank 1 misfire code. So I changed all the spark plugs, and that cylinder coil. Still no go, light came back on, and doing the same thing. So I took it to a shop, they pressure checked all the cylinders, and determined that it must be the fuel injector. So after $900 I now had a new cylinder 1 injector. Well a week later, symptoms back, engine light back on. Black smoke will sometimes come out of pipes upon starting sometimes. Oh and it only gets 11 MPG, no joke and that's driving like an old lady.

Now, It is bank 1 and bank 2 misfire. I was just told to try and replace the coil on cylinder 2. But they thought it was interesting that 2 and 1 are bad since 2 fires then 1 fires in order.

They are thinking that either the camshaft sensor is going bad (but no code?) or something is wrong with the computer. They did say it sounds like it could be a busted headgasket between cylinder 1 and 2 causing both to throw a misfire code.

Anyone have a clue here? I am about to trade it in next week and take a big hit and get a Lexus or Infinity. I am going to replace the coil on 2 this weekend and I might just take a big hit on the trade in just to get out of it.

What do you guys think? I am torn I love this truck. Well the way it looks...

No codes?
Try looking for a vacuum leak...
Try unplugging MAF... (smoke, misfire and poor consumption points to a rich mixture)
- speaking of which, is it running close to normal when cold?
Clean throttle body (though that would be only slight hesitation)...
Try throttle body adaption (not sure of procedure on a Q7 - bound to be posted here somewhere)...

Maybe repost this in Q7 section.

Carbon deposit. You need to clean the manifold. Or you can try sea foam like I did to my 07 q7 4.2, it got check engine light, multi cylinder misfire, hesitate from stop. Everything back to normal after 2 can of sea foam treatment from brake boost vacuum line. And it's been 10 months and 5000 miles, still drives great.

I know this my sound dumb, but where is the brake boost vacuum line? I know where they are on almost every car, but on this thing, I cannot tell what is what. I do need to try that.

And yes, it does run normal when its cold out, and has a full tank of gas. It starts acting funny when I am running low on gas, have the AC on, and its warm out. I am not sure what the actual code is, I take it to a auto store and have them run it. It all the said was bank 1 and 2 misfire, and then a multiple misfire code.

I am changing out the cylinder 2 coil today.

Oh and a point to make, this all started when I added a fuel system cleaner to it!!! That GUMOUT full fuel system treatment. Been jacked up ever since.

It still makes me sick to think I spent $1,000 on having an actual fuel injector replaced..

https://www.audiworld.com/forums/members/tlasher69-279984/

Good Luck

Considering the labor involved, that's not a bad deal. I had the very same issue as you on cylinder #2. I paid $245 for the injector and seal kit from a local dealer and did the work myself. I also spent $42 on the manifold gaskets.

these procedures are exactly what I would try first.
disconnect maf and drive. see if difference.
clean whole air intake, filter, throttle body, maf.
definitely think acuum leaks are a big evil on these cars. try a smoke test and visual inspection

Funny you replied. It ran perfect all fall and winter. Now that temps are back up, a/c on, its doing the very same thing again. No clue what those things are causing