Volvo AWD Forum

INDEX FOR 10/2025(CURRENT) INDEX FOR 2/2005

[<<]  [>>]


THREADED THREADED EXPANDED FLAT PRINT ALL
MESSAGES IN THIS THREAD




  REPLY TO THIS MESSAGE    PRINT   SAVE 

Where to begin

posted by  stonybrook on  Sat Dec 14 06:59 CST 2013
Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
last visit: Sat Sep 6 12:30 CST 2014
[RELATED]

Hello all,

Since I changed the Cat on my V70, the MPG went from 20 to 26. So we also have a XC70 (both 99) that is getting around 19.5 according to the dashboard calculator.
The XC also has thrown a P0455 code. Any connection between the poor mileage and the code?








  •   REPLY TO THIS MESSAGE Replies to this message will be emailed.    PRINT   SAVE 

    Where to begin

    posted by  KlausC on  Sat Dec 14 10:54 CST 2013
    Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
    last visit: Fri Oct 24 10:15 CST 2014
    [RELATED]

    P0455 = large leak in EVAP system. Not mileage related. Either a loose gas cap, purge valve stuck, or a cracked J hose problem.

    Your XC probably is still using the original front O2 sensor. They should be replaced around 120K miles or so and will dramatically improve the mpg. Also look around for leaking vacuum elbows as reduced vacuum will also decrease mpg.







    •   REPLY TO THIS MESSAGE    PRINT   SAVE 

      Where to begin

      posted by  stonybrook on  Sat Dec 14 18:08 CST 2013
      Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
      last visit: Sat Sep 6 12:30 CST 2014
      [RELATED]

      Had the front O2 replaced about a month ago. CEL was on indicating front O2 so I had it switched when i had the turbo oil leak fixed. light was out for about a month, then this one comes on. I was very surprised at the MPG improvement when i swapped out the Cat on my V70,9This one is the XC-70) I wonder if it could be the same. I wiuyld love to by pass the cat altogether and see if that improves MPG.








      •   REPLY TO THIS MESSAGE Replies to this message will be emailed.    PRINT   SAVE 

        Where to begin

        posted by  KlausC on  Sat Dec 14 19:10 CST 2013
        Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
        last visit: Fri Oct 24 10:15 CST 2014
        [RELATED]

        I do not suggest anyone removing the cat, the O2 sensors drive the timing and the fuel/air mix. Besides, testing stations don't like it.

        If your XC gets 26mpg on the highway, feel good about it. If you only take short cold engine trips, 18-20mpg would be great.

        So, now all you can do is look for vacuum leaks around the intake manifold, the boost control solenoid (by air cleaner), and the fuel pressure regulator (passenger side sub frame under the firewall).

        If you are running 87 octane, try a tank of 89 octane.

        Next oil change, switch to 5W-30 for cold running engine.

        Check the tire pressure. Check the rear brakes for drag.







<< < > >>



©Jarrod Stenberg 1997-2022. All material except where indicated.


All participants agree to these terms.

Brickboard.com is not affiliated with nor sponsored by AB Volvo, Volvo Car Corporation, Volvo Cars of North America, Inc. or Ford Motor Company. Brickboard.com is a Volvo owner/enthusiast site, similar to a club, and does not intend to pose as an official Volvo site. The official Volvo site can be found here.