Can high idle cause high fuel consumption? - 1982 245 w/B230E

Discussion in 'Volvo 240' started by Chris, Aug 28, 2007.

  1. Chris

    Chris Guest

    My 245 runs very nicely but the fuel consumption seems far too high. I
    am averaging 7.5km per litre, or about 20 imperial mpg. I recently
    cleaned the throttle body. It was not very dirty even though it had
    not been touched in over 40,000km. The car has EGR fitted - the pipe
    to the throttle body was completely blocked so I cleaned it out. When
    re-assembled the car idled at about 1500rpm - previously it was about
    1000rpm in neutral, 850rpm with drive engaged (3 spd auto). I used the
    knurled nut below the TB to adjust the idle, but when fully seated the
    idle is now 1200 in neutral, 1000 in drive. I can't get it below that.

    Since I cleaned the TB the other strange occurence is that the engine
    fires from cold almost immediately but then stumbles, idling at about
    400rpm for about 5 seconds, before rising to 1200rpm almost
    immediately. It runs very smoothly on the highway at 120km/h. Uses no
    oil between 5000km oil changes.

    I have not really paid much attention to the fuel consumption until
    recently, but 20mpg, averaged across city and highway, seems too high.

    The fuel injection does not have an electonic throttle position sensor
    and no air mass meter. Its an Australian model. Air filter, plugs and
    oil are all new. Airbox seals well and the heater thermostat in the
    airbox is open (I don't think it ever gets cold enough in Sydney for
    it to lose during the day). Fuel pumps replaced last year. Almos new
    OEM exhaust system. The rotor cap and rotor are quite old but car
    starts and runs great so can't see any problem there? Thermostat
    replaced lat year, temp needle in middle of guage.

    Based on another post I disconnectde the vacuum hose to the EGR and
    plugged it, but this has made no appreciable difference.

    why is my idle so high and how can I reduce it?
    can this cause the high fuel consumption?
    What else could cause the high fuel consumption (I do not accelerate
    hard in this car)

    thanks for any advice
    Chris, Aug 28, 2007
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