Idle and mpg problem

  1. Newbie Joined: Jun 2011 Posts: 7
    #1
    Howdy

    I am struggling to correctly diagnose what is effectively give me a less than acceptable mpg and an incorrect idle rpm?

    I bought a 1999 1.1sx SPI saxo 6 months ago with no MOT.

    When I got it, the oil was a milky brown, not quite as bad as what I have seen a car with before where the head gasket had gone, but enough to make me investigate more! So I did an engine flush, radiator flush, new oil and and put radweld in it. Put a bottle of reddex in the fuel, and the car got through the mot fine and passed. 6 months later, the radweld has cured the oil/water mixing and is completely clear of the shit that was originally in it!

    IN a nutshell I am getting about 19mpg. I read through the great article on this site about getting better mpg, changed my driving style etc.

    The car idles at 1000rpm - is this normal for this saxo?
    When I go above 50mph for a few minutes or more, then dip my clutch when pretty much at a standstill it will idle about 500-600rpm - is this more normal? After I accelerate off again, the idle will return to 1000rpm

    This is what I have done so far to help diagnose/fix further:
    -Cleaned throttle body
    -Cleaned lambda sensor (on manifold)
    -Cleaned the idle control valve
    -Disconnected the battery for a while and reconnected to try and reset the ecu

    Also, I am not sure of the proper name for this, but it is the section between the rocker cover and the throttle body. This was really full of shit! Dark sludgy oily shit! Is this the vacuum? And should this be full of this?

    ANY HELP IS GREATLY APPRECIATED GUYS!!!
  2. Frequent Poster Joined: Jul 2010 Worcestershire Posts: 572 206 RC 180
    #2
    I had the same problem on my 99 vtr it was the lambda sensor replaced it for £30 and job done
  3. Newbie Joined: Jun 2011 Posts: 7
    #3
    Cheers ramigojag

    Does this affect the idling too? First time I have had a saxo, so not sure what these regularly tick over at...
  4. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #4
    could be a map sensor if ur car has one
  5. Infrequent Poster Joined: May 2011 hull Posts: 210 saxo vtr 1.6 8v
    #5
    i had an idle problem and i changed my temp sensor and it sorted it out no problems since
  6. Frequent Poster Joined: Jul 2010 Worcestershire Posts: 572 206 RC 180
    #6
    my idle was really lump ticking over around 700 rpm and was only managing to get 300 miles out of a full tank with sensible driving

    replaced the lambda sensor now it ticks over just a smudge under 1000rpm (just right) and can get 400+ out of my tank

    well worth the £30

    i got the part off ebay because didnt fancy paying the £90 from local auto factors
  7. Newbie Joined: Jun 2011 Posts: 7
    #7
    Cheers for that guys.

    Would anyone know if all these 1.1 with a cat on should have 2 sensors? I keep reading about pre and post cat sensors, but I have checked mine and cannot find any sign of one around the cat?

    CHEERS!!!