Engine surge hunting uphill under load 70 -75mph

Discussion in 'Engine' started by evo3500, Sep 21, 2016.

  1. evo3500

    evo3500 New Member

    Messages:
    11
    Joined:
    Dec 7, 2011
    Car:
    mercedes clk 230 and 430
    Hi guys,
    I hope some one may be able to shed there wisdom with my fault.
    I have a 2004 ml 270cdi just purchase.
    Very pleased with it but lol.
    When I test drove it no where to get it up to speed so didn't know it had a fault.
    So here's info on the fault and symptoms.
    Car starts up eagerly 1st turn of the key and settles straight away into clockwork smooth tick over.under normal driving I cannot fault the way the engine box performs smooth powerful no issues. I will make you aware of these two other faults with the car invade they have any bearing.
    Engine temp on dash didn't get to 80 deg c only about 75 deg c.
    Esp bad light on sometimes didn't seem to effect the cars driving.
    Back to the main fault.
    On the flat the car cruises at 70 or 75 I can't remember exact speed engine rpm is 2500 engine smooth no pulsing surging as you go onto an incline and there is a load the engine has a rhythmic pulse every few seconds the rpm fluctuates drops to 2400 then back to 2500 you can feel it doing it up and down every few seconds once the road levels out it stops. It doses this in cruise or on a steady throttle cruise off. The car has 165,000 on it so is just run in lol.
    I am having a gearbox service done next week as a matter of course because I don't know if it has been done. I have read this might be a cause as torque converter may not lock up if fluid level low or oil quality bad. I have also read torque converter solenoid/ switch can cause it.
    I am going to get it plugged in today and will post any fault codes later.
    I would love to get this fixed as the car is fantastic apart from the annoying fault at the speed you drive on the motorway.any help advise appreciated.
    :thumb:
     
  2. OP
    OP
    evo3500

    evo3500 New Member

    Messages:
    11
    Joined:
    Dec 7, 2011
    Car:
    mercedes clk 230 and 430
    Have plugged in car today no fault codes ar all ? except for ones relating to bas esp light on. c1210 +30 voltage below threshold intermittant,c1142 esp brake pressure sensor plausability error intermittant,c1174 steering angle sensor not initialized intermittant,and c1170 zero compensation of steering angle sensor intermittant.

    There is no fault codes relating to the main fault of the revs hunting.

    could a faulty or on its way out fuel rail pressure regulator cause the symtoms ?
    I am going to try to take some real time data and a video of the fault as it is happening to see if it picks anything up.

    will update.

    Anyone got any other ides tests to do:dk: ?

    thanks all
     
  3. OP
    OP
    evo3500

    evo3500 New Member

    Messages:
    11
    Joined:
    Dec 7, 2011
    Car:
    mercedes clk 230 and 430
    Anyone got any ideas ?
    Thanks
     
  4. OP
    OP
    evo3500

    evo3500 New Member

    Messages:
    11
    Joined:
    Dec 7, 2011
    Car:
    mercedes clk 230 and 430
    Well put the car on star today no faults stored
    Had torque converter disabled to test if gearbox related no different
    So guess it's engine sensor related mad or egr
    Going to plug madf vacuum and test to see if fault goes if it does egr.
    If not going to go for a genuine mag it's been replaced before by previous owner but not a pier burg
    I'll update soon
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.