terrible gas mileage

dman123 · Post by **dman123** » 03 Dec 2006, 19:33

I have an 1994 850 turbo that runs great but is getting about 13mpg in the city. I fill the 70litre tank to get 300km or 187miles from the tank. I see that my PCV system is clogged. Can a clogged PCV have that dramatic of an effect on gas mileage or is my problem probably something else. I've done plugs and injector cleaner. No 02 sensor codes or engine lights...

dman123 · Post by **dman123** » 03 Dec 2006, 20:50

sorry my car has 190 000km on it. I've also followed the instructions at http://www.volvospeed.com/CheckEngine.php to check for any codes, but it doesn't seem to return anything... when I have the jumper in any of the sockets and then press the button for a second nothing happens... anyone know why?

White850Turbo · Post by **White850Turbo** » 04 Dec 2006, 06:28

Examine all of your vacuum lines and elbows very carefully. Pay special attention to the one on the passenger side of the intake manifold. It's kinda tough to see, but it's there.

Volgrrr · Post by **Volgrrr** » 05 Dec 2006, 18:47

Apart from poor fuel economy, if your crankcase cannot breath freely, then there is the real risk of the crankcase being pressurised and blowing a real oil seal.

This can be very expensive to repair.

I wouldn't waste any time correcting the situation.

Post by **MadeInJapan** » 05 Dec 2006, 20:04

Volgrrr wrote:Apart from poor fuel economy, if your crankcase cannot breath freely, then there is the real risk of the crankcase being pressurised and blowing a real oil seal.

This can be very expensive to repair.

I wouldn't waste any time correcting the situation.

What is being said here is to get your PCV system serviced....this usually means replacing the oil separator under the intake manifold as well as all of the small vacuum hoses, especially the one that runs to the PCV nipple at the base of your air intake (larger- accordian type) hose. This will help your car breath better and will be good insurance against pressure build up that tends to kill engine seals and cause you to loose money like your pockets have holes in them.

dman123 · Post by **dman123** » 05 Dec 2006, 21:01

ok, i've been examining the car for a whil;e now and I found 2 elbows that have major leakes. Both are the ones that come out of the vacuum tree. 3 go in a 2 come out and its the 2 that come out that are damaged. What do these vacuum hoses do and should I replace this with the stylin motors silicone tubes?

dman123 · Post by **dman123** » 05 Dec 2006, 21:18

ok. i've ordered the silicone vacuum hoses from stylin motors. Now I want to clean my PCV system as well, but I don't want to order the entire PCV kit from fcpgrotton (since I will use the silicone tubing instead) What other parts will I need to service my entire pcv? Will the silicone vacuum hoses work for the hose that goes from the top of the crankcase to the oil trap? thanks

dman123 · Post by **dman123** » 06 Dec 2006, 17:22

in the PCV diagram at
http://img141.imageshack.us/my.php?imag ... rboww7.jpg
what is the #7 hose/pipe? can I use the silicone tubing supplied by stylin motors instead of purchasing that part from fcpgroton?
Is everything in this diagram simply vacuum hoses and elbows and clamps except for the oil trap? thanks in advance.

Post by **MadeInJapan** » 06 Dec 2006, 21:03

#7 is a special pipe with a special connector on the end of it...it connects the oil separator to the heated PCV nipple on the end of the air intake hose (to the turbo or if an NA, to the throttle). It can't be substituted. Actually, most of the PCV kit can't (like the wide but short pieces that butts the oil trap up to the engine, etc.) so I would go ahead and spring for it...your Stylin' hoses will come in handy every where else and you'll use most of it for the other stuff anyway. If you buy the kit from Groton on eBay, you'll get the intake manifold gasket with it and it's actually cheaper than ordering from them directly. Good luck.

dman123 · Post by **dman123** » 06 Dec 2006, 22:10

thanks for the reply