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The car is a renault Grand Scenic ii 2005 1.6 16v

I am really stuck with my car (sorry for putting this here but im getting no response from any other site or forum)

If I'm parked on the drive with handbrake on and pump the brake pedal, the car vibrates really bad, then dies down again after 4-5 seconds. My car vibrates on and off when stationary, but gets worse when driving. I have also noticed if i'm traveling at 50 in 4th gear the vibrations are still the same. If I go to 5th gear, it gets more aggressive (there is no shaking with the vibrason, but I can feel a bit in steering wheel and really bad on gas pedal).

I'm stuck. I've had the car in a garage and they are finding it hard to find why it's there. Work done to car

  • shocks
  • wishbone arms
  • track rod end
  • anti=roll bars
  • springs
  • all exhaust, engine, and gearbox mounts
  • new clutch and clutch hydraulic cylinder
  • head gasket set including valve seals, valve resetting
  • disks and pads
  • spark plugs
  • water pump
  • timing belt
  • all filters and oils including brake fluid

And I'm still stuck with the vibration which only came when I changed the old engine mount which was so worn the engine could be pushed right back and forwards by hand which was banging when moving.

I forgot to say the vibration is bad enough the driver side wiper will vibrate on the window too.

Sorry for the long text and thank you for your time if reading it but I've spent a lot of time and money on the car and don't want to get rid of it just because of the vibration.

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  • Welcome to Motor Vehicle Maintenance & Repair! I've cleaned up your question a little bit for readability's sake. If I've misinterpreted something, please edit it and correct it for us. I think all of us can feel your pain. As for the vibration, I'd bet it was there even before you changed the motor mount, it's just you weren't feeling it. Big question for you: Are there any engine codes (check engine light on)?
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Sep 27, 2018 at 20:59
  • The engine light don't have to be on for error codes :) sounds like you still have another motor mount that needs changed, if you changed one you might have put at the stress on the other bad one, can you feel the play while pushing on the hood, can you feel it with the tires off the ground, can you feel it pushing on the engine ?
    – user38183
    Commented Sep 28, 2018 at 2:01

1 Answer 1

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Pumping the brake pedal makes the car vibrate - This sounds like a possible air leak on the brake servo making the engine run with a weak mixture. This will cause a misfire, hence the vibration.

Does the engine run well normally when driving, or do you have a lack of power?

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    Nutz; you beat me to it. This is without a doubt the first place to look. My first instinct. Also explains why engine smooths out after a few seconds - the ECU has enough time to compensate to some degree. Classic "vacuum leak" symptoms, but a rather rare brake servo/booster origin. Time to reiterate Paulster's suggestion of looking for codes and/or do PID monitoring with a good OBD II tool. If the AF, or even the O2 graphs show real-time effects when merely pumping the brakes at idle, I suspect you'll know where to look. Disconnect and plug the vacuum line to the booster, and repeat.
    – SteveRacer
    Commented Sep 28, 2018 at 3:51
  • Thank you both the car has had lack of power since I brought it ( it will lose speed going up hill even in 4 gear with gas tuching the floor) i do have a rrnault can clip witch nothing is show up on diagnostic of all computers i will try and investigate with what you said and let you know how i get on. Thank you for your time and i real do appreciate it
    – user41927
    Commented Sep 28, 2018 at 5:10
  • You may be able to hear the air leak if you get close to the brake servo/booster
    – HandyHowie
    Commented Sep 28, 2018 at 6:49

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