terrible gas mileage

Tsquared · Post by **Tsquared** » 22 Jun 2007, 05:13

waynej wrote:After replacing the plugs, plug wires,cap and rotor, then get it up to highway speeds for at least 30 minutes to burn the carbon off the o2 sensor. You may also have very dirty fuel injectors. Dirty injectors don't properly atomize the fuel and it doesn't burn completely. Chevron puts injector cleaner in all their grades of gasoline. Most other companies put little or non in the lower octane fuels. You can buy a good cleaner from Chevron or Red Line. The instructions on the cleaner say to put a bottle in a full tank. I put a bottle in a 1/4 or 1/8th tank. Then take it out on the interstate when it's not to busy, accelerate to 75 then slow to 40 and accelerate to 75 again. Do this about 5 or 6 times then fill the gas tank. If you leave the high concentration of cleaner in the system for more than a few hours the rubber seals may turn to mush.

When you accelerate you need to go wide open throttle (WOT). This will provide maximum pressure through the injector.

waynej · Post by **waynej** » 22 Jun 2007, 12:02

Very true
Thanks for the correction.
It helps to have a car full of people so,it takes longer to get up to speed.

rokkein · Post by **rokkein** » 09 Jul 2007, 20:15

this past week I tried the most basic fix and it seems to have worked. i switched to 93 octane gas and dumped in one bottle of fuel injector cleaner. i saw some mild improvement, but mostly this was city driving and hard to tell. i then filled up again with 93 and used more fuel injector cleaner (i dont think the previous owner ever did this) along with a bottle of dry gas. The first full tank of highway driving got me up to 27mpg. On my way back home I was getting over 30mpg -- this in a '96 850 turbo!

icelandic · Post by **icelandic** » 10 Jul 2007, 07:36

Your car is not a turbo, correct? If it isn

sergoparia · Post by **sergoparia** » 10 Jul 2007, 20:58

Iceland, I got the same problem
Could you please give me a hint where can I find that easy fix for the valve.
Thank's.

Post by **Ozark Lee** » 11 Jul 2007, 06:06

Could you please give me a hint where can I find that easy fix for the valve.

There is a good thread on the subject here:

https://www.matthewsvolvosite.com/chat/p ... php?t=8830

...Lee

sergoparia · Post by **sergoparia** » 11 Jul 2007, 16:01

Thank's again Ozak Lee

But, does that valve really affects so much the fuel consumption?

Post by **luketrash** » 11 Jul 2007, 16:07

The flapper thermostat failure causes hot air to be drawn in. Less power = more gas used to get up to speed. Hot air from the exhaust could possibly fry or accellerate the lifespan of the MAF sensor as well. I had mine bypassed all winter and the car was running fine. No real need for it (other than emissions purposes.)

I have my flapper bypassed and it made a noticible difference at the time. However, I only get about 19mpg in town with my normally aspirated 850.

I'm chasing similar issues as you are. I've got new plugs, cap, and rotor in the car at the cost of 200+ dollars and everything is still the same.

So good luck

sergoparia · Post by **sergoparia** » 11 Jul 2007, 17:02

Thank's Luketrash,

I am only dreaming about 19mpg in the sity,
Mine does only 15. I have changed O2, plugs ( didn't touch rotor and wires though), replaced timing and drive belt, oil, flashed transmission with Mobil 1. Nothing.
Still keep getting p0133 code and the mileage is really bad.
So I am putting all my hopes on the air thermostat. I read your treads and it seems really helpful for a lot of guys.
Otherwise I might tray to change O2 again and/or MAF.
But again, it is $$$ and absolutely no guaranty of improvement.

So, I'll keep my fingers crossed.

damnyankee · Post by **damnyankee** » 11 Jul 2007, 19:50

Just tonight I did this fix as well. The aluminum tube from the manifold to the aorbox got trashed this winter while I was working on the car and I never replaced it, it never dawned on me about the thermostat in the airbox!!

To date on my commute of 60 miles round trip 54 are interstate and 6 city driving I avg. a solid 25 mpg.( I run 70 mph). I will check and get a new reading and keep you up to date. I was going to clean the MAF tonight but will wait to see what this does to my mileage first so I know what this fix did.

Bear with me as I have started car pooling and will traveling the next few weeks so it may take some time to get an accurate mpg.