I too noticed a chunk of the plastic missing from the air handler, near the top engine mount. I must have nicked it when putting it back on. I sealed that off with some tape, and that took care of the erratic idle/stall problem I was getting on decel after replacing the spark plugs.

 

My XC 90 has been stalling intermitently over the last 10 months too. I have replaced MAF, spark plugs, fuel filter, and I can't remember what else. My battery was old and one day the car wouldn't start so I repalced it and, (cross my fingers), it hasn't stalled since.

 

I’m putting this down for the record and history for future frustrated Volvo owners that are struggle for answers.
So I had the same problem,…I have a 2004 XC90 AWD T6 turbo…It would start up, but would run really rough and when it would idle (about 500 RPM) or at a stop light it would die. Now keep in mind it would start back up and idle okay in park but as soon as I would engage it to Drive or Reverse it would die again. You could do this all day. Sometimes it would be okay when cold but once warmed up it would start acting up…Sound familiar?
So steps I took:
1. Checked for vacuum leaks with some carb cleaner and sprayed all around checked all hoses and vacuum tubes. Made sure nothing was off. Sometimes hoses are not clamped on right or disconnected completed, trace back all hoses… (in my case nothing.)
2. Replaced Mass Air Flow Sensor (MAF), stupid mistake is I bought an aftermarket one that was not a Bosch. For some reason Volvo computers do not like aftermarket MAF sensors and it actually acted worse than before. DO NOT WASTE YOUR MONEY. Trust me on this no matter what anyone tells you,… hunt around and you will find a true Bosch part for about 100 bucks save yourself the grief.
Replacing the sensor helped with the rough idle. So I consider that a win. However it was still dying…
3. Look at the fuel filter, you can tell if it is the factory filter because it usually has tape around the input and output part of the filter, and it maybe brittle. If the fuel filter is old and clogged it may not have enough fuel pressure to maintain and idle, hence the dying…
4. Spark plugs… Volvo’s have this finicky thing with spark plugs as well… its best that you use the Volvo OEM plugs as that is up to specs, but I have successfully used the NGK V Power COPPER plugs. They should be gapped to .028 to .030.
Now when I was pulling off all the vacuum housing to get to the plugs, INSPECT the hard case tubing…
What I found…. The left engine mount was slightly bend and broke the side of the hard case tubing to the rear turbo tube…. I never would have found it had I not taken off all the tubing to swap out the plugs. I patched it up and it seems to be working great now….
Cheers…

 

rsd911

Did replacing the MAP sensor stop all of the problems? I have replaced my MAF sensor on my 04 xc90 and am still having idle issues. So, wondering if my problem is similar.

Thanks

 

No. Not completely... It's interesting when I first start it cold there is no stalling issues, however if It has time to run, warm up and then you start it again not soon after. It will stall every now and again but will get going after a few starts and you let it run about 1000 RPM's.
After further review it is determined that my throttle body Will need replacing or at minimum cleaning. However this part is in the thousands and has to be done but Volvo directly as they have to program the new part and can not be done by the garage mechanic.

 

That is interesting about the warm vs cold engine situation. The issues with my vehicle seem to be consistent no matter the engine temp. Before taking the car in to have the throttle body cleaned, I replaced the fuel filter and that was much easier than I thought it would be and only took approx. 15 minutes.

I paid $800 for the throttle body to be cleaned at the Volvo dealership near me. The car runs much better now that the throttle body has been cleaned.

The dealer told me that the MAF sensor is still throwing a fault code. Along with replacing the fuel filter, I had installed a non-Volvo MAF sensor - initially, it actually seemed to make the engine run more roughly. I have read on this forum in other posts how a Volvo or Bosch MAF sensor is the way to go. I may end up buying one after all.

 

I wanted to let others know we had a confirmed crack in the air intake going to the turbos after that MAF sensor. The motor mount broke and pushed into the plastic intakes cracking and causing a lean mixture due to more air being added after the MAF.

Are symptoms including stalling while coming to a stop RPMs would not stay above 500. This got worse as the engine got warmer. Due to the high RPMs in initial start never experienced it right away.

 

That is terrible and sounds very expensive. I was fortunately able to resolve the issue I was having by purchasing a genuine Bosch part. It was used and significantly less money that way and solved my issues. The aftermarket part improved engine performance, but the computer did not recognize the part as it was not the original manufacturer's part. I have also experienced this with my daughter's Volkswagen. Non-Volkswagen genuine parts would "fix" the issue, but the computer would still throw codes. I've learned my lesson on foreign cars - must be made by the original part manufacturer and not just OEM specs.

 

mine did the same thing. After trying many things replacing parts. It ended up being a large crack on the top right bottom corner of the air manifold near the engine mount . It was not visible without a mirror. Fixed the problem instantly.

 

after all this time I'm sure they resolved it but was it me, did I miss any codes that were pulled those parts throw codes.

 

I had the same symptoms after replacing spark plugs (yes, Volvo plugs!) and a new Bosch MAF Sensor on my 2004 Volvo XC90 T6 AWD. I somehow didn't notice the broken piece off of the Inlet Pipe near the Top Motor Mount till my girlfriend found the piece the other day. Took the Inlet Pipe off and Voila! Piece broken off. I'm going to try J-B Plastic Weld on it and some electrical tape for good measure. Here are photos of the break:

 

For those having this same issue and pulling their hair out, add another victim of the plastic turbo inlet pipe being broken by the driver side engine mount. Mine looked almost identical to toddster1's and was the source of all my trouble. Replaced it and have been trouble free for years now.