This one I can't figure out. Now that it's winter my 850 2.3 turbo will occassionally not have much power. I can press the accelerator all the way down, it has full throttle travel but the engine will not rev up. It sometimes stops at 1700 to 2000 rpm with very little power. The car will move but it has no power. If I start it, let it run five minutes, let it sit and then start it again later it will run fine. I've had to drive it this way a couple times needing to get to work and it will be hard to get it up to 55 mph. Any mild incline will cause it to lose speed and downshift. The rpms go up but it adds almost no power and it will slowly drop speed sometimes downshifting to second and getting down to forty on the freeway. I have no clue. Everything I know about an engine makes me think that when I floor this thing it should stumble as the throttle plate opens up and it should lean out. It doesn't do that it just comes up in RPM to a point and runs at that rpm no matter how far down I push the pedal up to and including all the way to the floor.
Any idea what might be freezing up and causing this?

Once it sits a while and I drive it again all the power and rpms are normal. It only happens when it's below freezing and then only here and there. I haven't been able to see any pattern to what might cause it other than it's never happened when it's warmed up or above 32 ? ? ?

 

Try unplugging your water temperature sensor in the thermostat housing and see if you experience the same symptoms.

Other thought that came to mind is a frozen turbo. Very rare but some have had it happen.

 

I wonder if there's any water in your fuel too. That could cause some of these symptoms too, I think. Sounds odd, but when was the last time you changed your fuel filter? if you have a bunch of water/debris in there, its possible that you just arent getting fuel.

 

This is my first year with the vehicle. When I purchased it in the spring I did plugs, wires, cap, rotor, air and fuel filter. I also replaced the timing belt with a component kit as I had no maintenance history on it. I've cleaned the throttle body and idle air control motor and except for replacing the fuel pressure regulator with a slightly higher pressure one and taking a turn out of the turbos actuator arm haven't really done any modifications from stock. All this was done before the weather started to get cold and back then there were no problems. It does need a new PCV system and due to the oil I get seeping back out the oil fill cap and dipstick tube I know I have a bit of pressure in there. That pressure and the condensation that goes along with the lack of venting is why I think it's an icing issue. I just can't think of what could get iced up that would restrict rpm and power. I will try the coolant temp sensor though. No check engine light and the gauge is registering correctly.
Thanks for the input.

 

I had it happen again for a couple days now. It's been at and under 0 degrees this last week. I did find I have a physical restriction as when I have this problem the intercooler hose at at the top of the radiator (outlet) leading to the throttle body will collapse as I thumb the throttle open. I checked the hose at the bottom of the intercooler (inlet) thinking that maybe years of neglect had possibly caused enough condensation to restrict the hose but the hose was soft, pliable and no ice was felt. It's too cold to check it now but that leads me to think I have a turbo problem. Is it possible that the bearings are hanging up and it's not spinning?

 

I haven't started to take it apart yet but I'm pretty sure my turbo isn't spinning. When I hit the throttle under the hood and watch the rubber intake hoses collapse it's leading me to think it's pretty much the only thing it could be. The temperature is finally getting over 30 degrees so I might take a hose off at the throttle body and see if it will rev up. If so, I'm screwed and it's the turbo.
It's just been sitting in the driveway the last couple weeks due to the really cold temps and it's now acting up all the time no matter what the temp. Starting to think it wasn't really the temperature at all just happened to start to fail as the weather turned.
Anyone else have a turbo just lock up on them ?

 

Remove the hoses connected to the turbocharger and make sure the bearings are not seized. Small oil leak under the turbocharger is normal and is of no concern. However, it is probably only a part of the problem as you've described it only happens when it's 32F> when the engine is cold.

When you have had the tune-up, did you use OEM parts? Volvos are extremely sensitive to the quality of parts.

Check the tranny fluid for proper colour & level; it should be clear red and must not be under/over-filled. It must not have burnt odor to it. If a fault is detected by the TCM, the car gets into "Limp Home Mode". In LHM, the RPM goes up but not the vehicle speed. It feels extremely sluggish.

See attached for troubles without CEL turned on. I would also try to pull codes from the EEC & TCM even though CEL is not on. If your 850 is of '94-'95, you can do this by yourself and no special tool/tester is required. If it's '96-'97, visit an auto parts shop such as AutoZone and have your car tested via OBD-II. In general, OBD-II is equipped for cars made after 1996 but tell them that even though your 850 is '94/'95, it does have OBD-II port in front of the shifter, right under the coin holder.

Without testing the car myself, this is the best I can do. I thought water could be trapped somewhere in the intake/fuel system and freezing up & restricting the system, but then once it is melted, it should get sucked into the engine and gets out of the tail pipe......


JPN

 

It may not be a turbo problem, but an intercooler hose problem. The hoses can collapse when they get old. Have you replaced them recently?

Also, there's a hole at the bottom of the intercooler that should allow small bits of gunk out of the system. You may have to clean it out and then replace the 5 hoses.

 

It's been a year but in case anyone is researching this problem. I think it was just previous crap maintenance. I never did figure it out but I was pretty sure it was being caused by the turbo since the intake hose off the throttle body would always collapse when this was happening.
I'm thinking it was a badly coked up turbo and wouldn't spin on the bearings. This year I've been running synthetic and adding a quart of transmission fluid at the end of the oils life a week or two before I change it to help clean out the engine. Coldest mornings it starts right up the way it should and idles fine and when I'm ready to go so is it.

 

If the turbo did freeze it would still let air through. Look at the hose going into and the hose coming out of the intercooler....do both collapse or only the hose to the throttle body? There may be moisture in the intercooler that is freezing and blocking the air. If both collapse then the finger can be pointed at the turbo.