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Thread: C2 VTS (2004) rough idle / engine hunt at 1,000 revs

  1. #1
    Member N.L.Howell is on a distinguished road
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    Default C2 VTS (2004) rough idle / engine hunt at 1,000 revs

    Evening all,

    First time poster and I would very much appreciate some assistance.

    My little C2 VTS (56k on the clock) seems to be unwell and has a rather annoying low idle rev hunt at 1,000 RPM. The needle just bounces and revs vary from mid-800 to low 700 hundred.

    I have been looking online and reading various posts on the forum and I am wondering what people would suggest next.

    I have replaced the following so far which has made no difference

    ē Map Sensor
    ē Spark plus - Bosch Super 4
    ē Coil Pack
    ē ITG panel filter
    ē removed the throttle body and cleaned with Carb cleaner
    ē Iíve bought a crank sensor but not replaced as of yet

    I have checked the manifold for any leaks and all bolts seem to be intact and in place

    I'm not a mechanic but based on forum research I believe it could be injector/ fuel related but could of course be completely. I have disconnected the injectors one by one to see if any noticeable difference but nothing really jumps out at me apart from the EML coming on and the revs dropping
    When I spray a small amount of easy start into the induction opening this seems to cure the problem for a few seconds then it starts to hunt again

    The EML isnít on and no-fault codes occur, I have only had the car since February but it does feel a little sluggish and you have to give it a few revs when pulling away to prevent in cutting out.
    I have recently had the timing belt and water pump replaced due to the vehicle age and the Bosch battery doesnít look very old.

    I have read the lambda sensor and throttle body could be problem but Iím trying to eliminate things before spending money. The car was bought as a little run around and drives fine once going but traffic lights are bit of a pain with the car hunting and shaking

    I can make a little video of the problem but I have also taken some screens shots from my OBD reader. These reading mean very little to me but may mean something to someone else

    https://1drv.ms/f/s!AtZHdKy6UO_d43jqQcNj-Dl1hTTW (Engine Readings and video)

    Thanks for reading and any recommendations or suggestions would be very welcomed.
    Nathan
    Last edited by N.L.Howell; 29-08-2017 at 07:29 AM.

  2. #2

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    Check inlet manifold for security and leaks

  3. #3
    Member N.L.Howell is on a distinguished road
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    Ok thanks, anywhere particular I should be looking? Iíve taken the heat Sheild off and it all appears in order.When I spray around the area no change in engine noise.

    Thanks

  4. #4
    Member N.L.Howell is on a distinguished road
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    Slight update this morning, I have also uploaded a video of the dash.

    The hunting seems to stop when the air con is turned on, on the video the air con is turned on around 17 seconds and you can see the needle stabilize, the air con is turned off around 30 seconds and the needle starts to flicker again and the engine hunt continues.

  5. #5

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    Quote Originally Posted by N.L.Howell View Post
    Ok thanks, anywhere particular I should be looking? I’ve taken the heat Sheild off and it all appears in order.When I spray around the area no change in engine noise.

    Thanks
    Where it bolts to the head , the nuts come loose(or snap off), if it has done so also replace the gasket

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    Trek,

    Further to the above, I’ve checked the studs and all in place, removed the inlet and replaced gasket and refitted. Noticed a difference as in doesn’t feel like it will cut out now from take off . Hasn’t assisted with the idle hunt. Also replaced the lambdabank 1.
    Car has been to Citroen as I have a contact, hooked up and software flash but unable to diagnose.

    Wondering if you have any more ideas.

    Thanks

  7. #7

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    I have a similar problem with my 2006 VTS but only when i start It. For around 30 seconds idle jumps between 500-1000 rpm.
    I have change coilpack, check all intake nuts, change 4 spark plug and clean map sensor and throttle body but anythings change.

    I ll check fuel pump and try to clean injectors...There are the last things can i check!

  8. #8
    Member N.L.Howell is on a distinguished road
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    I’ve just bought a set of Bosch Injectors and rail from eBay £30 so that’s my next course of action. Like you if that’s a no go then fuel pump.

    I’m really scratching my head on this one although I am learning quite a lot at the same time.


    I know you mentioned you have checked the inlet nuts but I would reccomend cleaning the manifold and changing the gasket.

    Made a noticeable difference in respect of power and the cutting out side of things. Based on every thread in this forum I’ve read yours does sound like a manifold issue.

    Where are you located?

  9. #9

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    I m located in Turin (Italy).

    On my car i think that s the filter inside the fuel pump to make problem at low rpm.
    This filter Can t be cleaned because it s sealed inside the fuel pump. I want to check if It possible to open the fuel pump, eliminate inner filter and put an external filter (Like Saxo Vts or 106 1.6)

  10. #10
    Member N.L.Howell is on a distinguished road
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    Evening all,

    Following on from my original post, still haven't sorted my issue, however not really given it much time as of late.

    Left work and the bloody c2 wouldn’t' start, ticked over then died. The check engine light came on as well as the transaction control light I think (orange triangular light) for left of the mk1 gauge.

    The error code was P0336 which is odd as I’ve recently changed the crank shaft sensor with a new bosch one.

    As a result of trying to turn the car over the battery also drained rather quickly which may suggest it needs replacing as the date on the battery is 2012.

    Manage to Jump start the car with leads and the car it started first time. I’ve also taken some reading with my obd tool and placed them in my google drive.

    Would you mind taking a look to see if anything jumps out at any of you.

    https://drive.google.com/drive/folde...We?usp=sharing

    video 1. Engine Idle with rev range idle to 3k
    Video 2. Slight revs with release
    Video 2. Idle – no revs at all (this is the idle fluctuation while station that is annoying as hell.

    If anyone has any suggestions or feedback that would be great.

    Thanks

    Nathan

  11. #11

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    Did you get to the bottom of it i wonder?

  12. #12
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    I didn’t, still ongoing. Was going to pick it up again in the summer. Messaged a company to ask about increasing the idle bit they’ve basically ignored me. Haha.

    Do you have anything to bring to the party?

    Cheers

  13. #13
    C2 Addict Advanced Poster ozVTR is on a distinguished road ozVTR's Avatar
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    2012!! You are way over due for a new battery. Typical battery life is 4 years.
    If you run another battery in parallel with yours, like you were jump starting it, how does you car run?

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    Sorry, just to add the battery was replaced. Even with the new battery still an element of hesitation on initial crank. The car also still feels like it’s going to cut out on initial movement after start. Need a good few revs. Thinking I may strip it down and replace the gadgets on the manifold again.

    I’m sure the idle is potentially a valve issue but not sure how complex that type of job would be.

    Thanks

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    C2 Addict Advanced Poster ozVTR is on a distinguished road ozVTR's Avatar
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    Check purge control valve. Disconnect it it from the purge canister line (90' elbow) and put your finger over the hose on the valve side. Do this while the engine is idling.

    Check the vinyl hoses on the front of the inlet manifold (connected to purge) valve for cracks.

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    Oh. Check vinyl line that goes from the inlet manifold to the brake booster.

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    Thanks for the suggestions, I’ve done a bit of testing around the purge control valve. But can have another look. Where about is the line to the brake booster? Would either of these effect the car straightaway as my problem is once worm and and when the car takes ECU sensor readings

    Thanks

  18. #18
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    If you look at the brake booster, you will see a disc at roughly the 10 o'clock position. Attached to the disc is a vacuum line that goes back to the inlet plenum (
    the cylindrical chamber beside the throttle body and part of the Inlet manifold). The line can be completely removed for inspection. It has clips like the oil vapour and fuel connectors.
    If you are not having problems with engine performance at revs above idle that's usually but not always, small vacuum leaks. Check every connection/fitting from the throttle body back to the cylinder head and anything connected to those fittings, like the purge valve and brake booster line.
    Just to make things more clear: Closed loop = engine warmed up. Open loop = engine cold.
    Until the engine goes into closed loop mode the engine runs on a fixed rich mixture. When the engine goes into closed loop mode (warmed up) it starts looking at the engine management sensors and adjusts fuel and timing. A vacuum leak typically (typically, not all the time) is small and wont effect top end performance but does effect idle. It's possible, when in open loop mode, the rich fuel mixture is compensating for the vacuum leak. Because the C2 runs a Manifold Absolute Pressure sensor to calculate air flow, a vacuum leak will cause the engine to run richer (at idle) in closed loop mode.
    I doubt it would be anything critical like an injector or sensor as that would cause trouble at speed and/or under load.

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