A while ago I was lucky enough to find a black 850 Turbo wagon with leather and a 5 speed transmission. I absolutely love the car but lately it seems to think that premium gasoline is free. So here are all the symptoms:

It has always seemed to be slower than it should be. I owned a 20 valve 850 NA before and the turbo hardly seems to have the extra 54 horses that it claims.

The car uses around 10L/100Km (23.5mpg) at 110 - 115 Km/H(68-71mph) on the highway but the trip meter displays 8L/100km (29.4) .

The boost gauge shows pressure about 7/8 of the way and I can hear the turbo spool.
Plugs / air filter were recently replaced.

Tires inflated with nitrogen to what is on the fuel door (can't remember the actual value right now)

I was thinking a fuel leak or even a sticky injector, anyone else have problems with this?

 

could start by just checking your fuel pressure. that is quick and easy to do.

it *could* be a boost pressure leak but then you would prolly have/see some idle issue.

 

Last tune up?
Does it roll free if you leave it in neutral? - No jammed calipers or hand brake?

In general, these cars gas consumption is around what you are getting primarily becuase of these being still heavier cars with 2.3L engines.

 

what pressure should it be at?

 

The fuel pressure should be: 30-45 psi for aspirating engines 30-55 psi for Turbo engines

Caution! NOTE. At constant engine loads the fuel pressure should be stable. At acceleration or during engine braking the fuel pressure may vary between the maximum and minimum readings.


so in your case 30-55 psi

 

It rolls free (I can "easily" push it), it also has about 225K Kms on it. I normally do the basic maintenance that is in the service manual. I have only driven the car 25K or so but I am very surprised at how much fuel the thing uses in comparison to the NA 850 I owned. I will check the fuel pressure tomorrow as I need to get a fuel pressure gauge.

 

oh the car starts fine in cold and warm weather.

 

not sure where you are located. but if you are in the USA, autozone rents them for free

 

Unfortunately I am in Canada, it looks like there is a valve that allows for fuel pressure tests to be easily done. I am hoping that one of those guages is not too expensive. How much quicker is the turbo supposed to be? I just seems relatively subtle in comparison

 

yes, you can test right on the end of the fuel rail. the gauge is just a glorified tire gauge thats all (has seals and such to accommodate for the liquid fuel)

as far as the speed/acceleration goes i have no idea, have only drove NA wagons.

 

I read that there is a valve in the air box that is known to fail. It is supposed to let warm air off of the exhaust when the engine is cold and as it warms up the valve will let the cooler outside air come in. If it fails and only lets the warm air in, it will hurt your gas mileage.

Maybe someone else can explain this better because I do not know much about it.

 

Lower power and fuel mileage than expected; what comes to my mind is to check the compression. Low compression on one or more cylinders would give you these symptoms.

If compression is OK, next thing it could be is a slightly clogged cat convertor.

I am assuming no DTCs (diagnostic trouble codes) are set (i.e. is the Ck Engine Light on?)?

 

for your compression you are looking for about 160-190psi

 

I have a '97 960, '98 S70 and '95 850 R. The 960 hold its own but the S70 and 850 are FAST. You should definately notice and feel the difference.

My 850 R gets around 22 MPG.

 

The turbo ones are noticeably faster then NA in terms of take off .

The other thing I experienced is that the cat-convertors in turbo models have more chances of getting partially clogged due to some oil passing thru the turbo. The tailpipe on my turbo is kind of black from inside as compared to the clean metallic surface inside the na wagon. You can also feel the flow difference from the difference in sound thay make. - turbo is very silent due to sound mufling from turbo itself and then due to partially clogged catconvertor or muffler.

 

I did just a basic tuneup and it dramatically improved the cars performance. The acceleration is what I expected from the car. I will test for economy this week.

So what performance mods do people recommend for this car? I was thinking 3" exhaust and a remapped ECU. I am not sure which one to go for. The Speedtune is certainly one of the least expensive and I have all the equipment to replace the chip. The IPD solution seems rather pricey.

Any other ideas?