T6 getting 13.5 mpg and long starts when warm
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    1. #1
      Junior Member atraudes's Avatar
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      T6 getting 13.5 mpg and long starts when warm

      Last week the family and I were tooling around town and I noticed every time I went to restart it after sitting for a little while between stops (15 minutes or less), it would take a little longer to start. The final sign that something was definitely amiss was stopping the engine and restarting it less than a minute later. It took a good 5 seconds of cranking before it started. The weird thing is there doesn't seem to be any sputter or jolt, just a big delay and a start. After letting it sit for an hour or two after that it fired right up, no hesitation. Starting time has always felt a smidge longer than it feels like it should be, but I don't usually do a lot of quick stops.

      The other wrinkle was that I've filled up my tank 4 times in total, and have logged each fill-up in a mileage app that does some quick math on the number of miles you've traveled since the last fill-up and how much gas you put in. The second fill-up showed 15.5 mpg, and the last two have been 13.5. It didn't raise my eyebrow too much since this wasn't too much lower than my last car and I figured I'd give it some time for the injectors to get cleaned out and whatnot. However, after doing some looking into the long start condition, I found a few threads where folks with the T6 were getting a solid 18.5 in the city, and mid to high-20s on the highway. No one pitched in saying they were getting anything close to what I've been seeing.

      So, based on all of this, I went ahead and ordered a new set of injectors from FCP. In hindsight, sending them off to be cleaned would've been quite a bit cheaper but I convinced myself I'd get them much sooner with 2nd day shipping. Unfortunately thanks to the timing of their processing and shipping and alignment with the weekend it will have been about a week anyway. Oh well, lesson learned for next time.

      I also ordered a 5-point star bit set to pull the MAF sensor to clean it up. The fuel filter and spark plugs (blue box) are brand new and I cleaned the throttle body up not too long ago, so I don't expect any problems there. PCV system was also recently serviced. Once I have the injectors in and have gone through a tank or two I'll know if the mileage gets better and if the extended starts persist.

      In the meantime I'm curious if anyone has any other ideas on what could be up. There's more vibration at idle than I'd expect, but it's not shaking the car apart and it's not uneven. Acceleration feels smooth and responsive.

      Thanks in advance!
      2004 XC90 T6, 150k miles

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    3. #2
      Junior Member V50R's Avatar
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      It could be dirty fuel filter as well just a guess tho!


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    4. #3
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      I first read this car takes mid-grade fuel, but have recently read premium. I have been using premium. I would be using the best fuel you can afford and stay away from stinkin off brand and Arco smut. Fuel filter would affect the throttle more than ignition. I think you were right with the Injectors. If it's been over 30k miles since a fuel filter and you've been neglectful on fuel its probably time. Cheap filters will late 1/4 of the length of a good filter. Fuel can go bad after sitting for a month or more

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    6. #4
      Junior Member atraudes's Avatar
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      Good call on the fuel. I've been filling with premium (93, I think?) at Chevron. My last car got me in that habit and I've heard all turbocharged engines should be run on premium.

      The fuel filter is new. I tipped the old one over and didn't see too much come out so at least I know the tank isn't half sandbox

      I've only put 600 miles or so on the car so it's still pretty new to me. I'm thinking if the injectors or MAF sensor cleaning don't pan out I'll start looking at the upstream O2 sensors next. I can get them for ~$110 each so the cost isn't too bad, I'm just a little worried about how accessible they are.
      2004 XC90 T6, 150k miles

    7. #5
      Member Tommm's Avatar
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      How old is the battery? my buddy recently got a deal on a S60 2.5. it had been sitting a few months. the battery was dead. We jumped it with a battery we brought. It ran like crap. We started to negotiate a price, then swapped batteries. It ran like a champ.
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    8. #6
      Junior Member atraudes's Avatar
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      I could see that; I've heard the electronics on newer cars can get kinda wacky if they don't have sufficient voltage. Battery is new and the alternator was rebuilt.

      I just popped the new injectors in and unfortunately found some significant oil in the high pressure charge pipe on the driver's side. I'm guessing that means either something's up with the PCV still or the turbo has an internal oil leak. I checked the oil level and had to add about 2 quarts. This car is certainly keeping me on my feet!
      2004 XC90 T6, 150k miles

    9. #7
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      Quote Originally Posted by atraudes View Post
      Good call on the fuel. I've been filling with premium (93, I think?) at Chevron. My last car got me in that habit and I've heard all turbocharged engines should be run on premium.

      The fuel filter is new. I tipped the old one over and didn't see too much come out so at least I know the tank isn't half sandbox

      I've only put 600 miles or so on the car so it's still pretty new to me. I'm thinking if the injectors or MAF sensor cleaning don't pan out I'll start looking at the upstream O2 sensors next. I can get them for ~$110 each so the cost isn't too bad, I'm just a little worried about how accessible they are.
      Where I'm at its 92 octane.
      How long have you driven the car for one trip? Miles/minutes/average speed? If you have a leak from the turbos and it's the return turbine, that would be something serious. I would pull the plugs and check for oil in the cylinders. Maybe a mini camera you can find for cheap that connects to your phone.

      Check you exhaust for an oil scent. Don't huff it, but the amount of oil cycling through a turbo is quite a bit and it would show up in the poop what the dog ate.

      How many miles do you have on yours? The engine in mine will be the 7th one that I have worked on. I've pulled the turbos a few times and it is not fun. That would be a whole engine removal job. I pray its a valve cover gasket and the turbos are fine.



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    10. #8
      Junior Member atraudes's Avatar
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      Hey folks, small update. Roostergenie, sorry I didn't respond. I saw your post and ended up getting distracted. My trips are generally between 5-10 miles, sometimes much longer, occasionally just a mile or so. I haven't smelled any oil or seen any smoke, but it's possible it only happens at full throttle. The engine has 150k miles and if it does end up being a turbo I'll definitely be letting someone else deal with it. I know my limits and mucking with rusty exhaust bolts is it.

      I have the PCV off right now and have a few interesting (but ultimately frustrating) findings. There was oil in each of the ports on the intake manifold, though it's *possible* that was the oil I used to install the new injectors since I've only put 20 or so miles on since I replaced those. The throttle body was still very clean without any oil residue at all. The rubber piping going into the intercooler is also still very clean. I snaked a long zip tie down the drain port for the PCV and didn't run into any obstructions until it bottomed out, and again, came out very clean. I took a length of hose and put it up to each of the three ports on the block and blew and was able to without any resistance. When I blew through the drain port I could hear the oil bubbling. Blowing through the pipe leading to the turbo intake was likewise open. The PCV box itself still looked fairly clean and didn't have any obstructions. Since the glove test passed with flying colors the other day I'm taking all of this to mean there aren't any obstructions in the PCV circuit.

      Part of the reason for me posting mid-teardown was to talk it out, list my findings, and hash out my assertions, and sure enough, I just had an epiphany. I had also checked the oil level to see where it was and saw it was now high, and it just occurred to me that I found the oil level low while it was parked in the driveway which is on a hill. Of course the oil level was low! I'm slapping my head so hard right now. It's in the garage right now which is perfectly level. I'll extract some oil from the dipstick tube and set the level right. I haven't put many miles on since I overfilled so hopefully little damage was done.

      At this point I'm going to pull the air and fuse boxes and disconnect the turbo pipe to make sure the turbo's still spinning fine and there's nothing alarming going on in there. If everything looks fine I'm going to chalk up the oil I found up to it being a Volvo and turbocharged and just keep an eye on things. It's kinda frustrating I spent a few hours on this, but at least I have the peace of mind that the PCV is draining properly.
      2004 XC90 T6, 150k miles

    11. #9
      Junior Member atraudes's Avatar
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      I ended up not checking out the turbo. Once I pulled the air and fuse boxes I remembered how much other stuff was going to be in the way still and I decided against it. I had other things I wanted to check out before the weekend was over anyway. I had spun it with my fingers not too long ago when I replaced the brake booster, so I felt like that was good enough for now.

      I also pulled the wheel liner on the rear passenger tire to take a look at the PEM (fuel pump module) and see if corrosion could explain the long starts, but sadly (?) found it had been relocated, presumably inside. If the long starts keep up I'll pull the rear seats and carpet to check on it, but if it was relocated there's a fair chance it's in decent shape.

      I did another oil change so the level is back on track. I'll drive on it a while and let you know how it goes!
      2004 XC90 T6, 150k miles

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