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  • FIRST POST
    • marcarm
    • By marcarm 20th Mar 17, 12:35 PM
    • 673Posts
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    marcarm
    Mondeo throttle lag
    • #1
    • 20th Mar 17, 12:35 PM
    Mondeo throttle lag 20th Mar 17 at 12:35 PM
    Mk4 mondeo tdci.

    When accelerating if you squeeze the accelerator too hard the car just revs for half a second or so before reacting and then going faster. It normally happens in 2nd and 3rd. Googling brings up some other issues with 'accelerator lag' , it's as if it's in neutral before finding the gear.

    This is the first diesel I've owned so not sure if this is normal or not, it also has the 6 speed box so also getting used to that as well. I did do a bit of research and some suggested it may be supermarket fuel so when I filled it up yesterday I used bp as well as a bottle of redex in case the engine is a bit gunked.

    Not a car person tbf so wanted a 2nd opinion before booking it in
Page 1
    • BeenThroughItAll
    • By BeenThroughItAll 20th Mar 17, 12:38 PM
    • 4,596 Posts
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    BeenThroughItAll
    • #2
    • 20th Mar 17, 12:38 PM
    • #2
    • 20th Mar 17, 12:38 PM
    Sounds more like clutch slip. If it's not an auto there's no gears to 'find' if it's already in gear. Revs rising before acceleration suggests slip.
    • Geodark
    • By Geodark 20th Mar 17, 12:39 PM
    • 730 Posts
    • 456 Thanks
    Geodark
    • #3
    • 20th Mar 17, 12:39 PM
    • #3
    • 20th Mar 17, 12:39 PM
    So are you saying that the revs rise before the car speeds up, ie as if you had your clutch pressed in? How old is the car and how many miles has it done? to me if the revs rise but the car doesnt speed up straight away it sounds like a clutch problem.
    • marcarm
    • By marcarm 20th Mar 17, 12:58 PM
    • 673 Posts
    • 814 Thanks
    marcarm
    • #4
    • 20th Mar 17, 12:58 PM
    • #4
    • 20th Mar 17, 12:58 PM
    It's a 58 with 116k on it.

    It is a manual, just I've googled the problem and it seems that it happens to others but nobody has mentioned the clutch slipping.

    The car is speeding up, but it seems as though there is a half second delay after using the throttle.

    So change gear, use throttle, ending revs while the car is speeding up slower that you would expect, then it seems to find itself and then speeds up faster.

    But if I have the car at higher revs before changing gear, then keep the higher revs when accelerating again it doesn't seem to do it, so that's what made me think it may be because it's a turbo diesel and I need to adjust my driving style, as my previous car was a non turbo petrol. We've not had the car long and this issue didn't seem to manifest itself on the test drive so that's what leads me to think it is me.
    • mcpitman
    • By mcpitman 20th Mar 17, 1:02 PM
    • 521 Posts
    • 359 Thanks
    mcpitman
    • #5
    • 20th Mar 17, 1:02 PM
    • #5
    • 20th Mar 17, 1:02 PM
    Mk4 mondeo tdci.

    I did do a bit of research and some suggested it may be supermarket fuel ......
    Originally posted by marcarm

    Where you buy the fuel will not matter, I have completed 90k miles in a 2.0diesel on supermarket fuel, hasn't missed a beat.


    Paying for "premium" fuel is like paying for a credit score.
    Life isn't about the number of breaths we take, but the moments that take our breath away. Like choking....
    • BeenThroughItAll
    • By BeenThroughItAll 20th Mar 17, 1:02 PM
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    BeenThroughItAll
    • #6
    • 20th Mar 17, 1:02 PM
    • #6
    • 20th Mar 17, 1:02 PM
    What you describe are the early symptoms of a slipping clutch. It really is that straightforward.
    • mcpitman
    • By mcpitman 20th Mar 17, 1:05 PM
    • 521 Posts
    • 359 Thanks
    mcpitman
    • #7
    • 20th Mar 17, 1:05 PM
    • #7
    • 20th Mar 17, 1:05 PM
    It's a 58 with 116k on it.

    It is a manual, just I've googled the problem and it seems that it happens to others but nobody has mentioned the clutch slipping.

    The car is speeding up, but it seems as though there is a half second delay after using the throttle.

    So change gear, use throttle, ending revs while the car is speeding up slower that you would expect, then it seems to find itself and then speeds up faster.

    But if I have the car at higher revs before changing gear, then keep the higher revs when accelerating again it doesn't seem to do it, so that's what made me think it may be because it's a turbo diesel and I need to adjust my driving style, as my previous car was a non turbo petrol. We've not had the car long and this issue didn't seem to manifest itself on the test drive so that's what leads me to think it is me.
    Originally posted by marcarm

    Sounds like turbo lag, would be worth cleaning up all sensors (throttle position, boost sensor, EGR valve etc) and see if that solves it.


    Are you changing gear and hitting less than 1500-1700rpm when new gear is engaged? If so, you are labouring the engine too much and not capitalising on the torque provided by the engine.


    Equally could be early signs of clutch slip...
    Life isn't about the number of breaths we take, but the moments that take our breath away. Like choking....
    • marcarm
    • By marcarm 20th Mar 17, 1:08 PM
    • 673 Posts
    • 814 Thanks
    marcarm
    • #8
    • 20th Mar 17, 1:08 PM
    • #8
    • 20th Mar 17, 1:08 PM
    Where you buy the fuel will not matter, I have completed 90k miles in a 2.0diesel on supermarket fuel, hasn't missed a beat.


    Paying for "premium" fuel is like paying for a credit score.
    Originally posted by mcpitman
    That was my thought as well but when I filled up it was the same price so thought I'd give it a go.

    I'll take it my my local garage and get the to have a drive of it and see what they say.

    Take it it's a price job if it is the clutch?

    Really annoyed as the car has been really well looked after, recently serviced and mot but guess they don't look at the clutch then. Having just bought the car and then having to drop some more money on getting the clutch replaced.................
    • BeenThroughItAll
    • By BeenThroughItAll 20th Mar 17, 1:08 PM
    • 4,596 Posts
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    BeenThroughItAll
    • #9
    • 20th Mar 17, 1:08 PM
    • #9
    • 20th Mar 17, 1:08 PM
    Sounds like turbo lag, would be worth cleaning up all sensors (throttle position, boost sensor, EGR valve etc) and see if that solves it.


    Are you changing gear and hitting less than 1500-1700rpm when new gear is engaged? If so, you are labouring the engine too much and not capitalising on the torque provided by the engine.


    Equally could be early signs of clutch slip...
    Originally posted by mcpitman

    Turbo lag doesn't explain the engine RPM rising whilst vehicle speed doesn't increase, though.
    • marcarm
    • By marcarm 20th Mar 17, 1:10 PM
    • 673 Posts
    • 814 Thanks
    marcarm
    Sounds like turbo lag, would be worth cleaning up all sensors (throttle position, boost sensor, EGR valve etc) and see if that solves it.


    Are you changing gear and hitting less than 1500-1700rpm when new gear is engaged? If so, you are labouring the engine too much and not capitalising on the torque provided by the engine.


    Equally could be early signs of clutch slip...
    Originally posted by mcpitman
    I'll have to look when I next go out in it but my thoughts were that it wasn't revved as much as it could be when changing gear, as well as it only really happening when trying to get up to speed quickly in 2nd and 3rd.

    Will see what the garage say this is week.

    The vehicle speed does increase, just not as much as one would expect. Problem is the vehicle is so much smoother than my last car you don't notice it speeding up as much without staring at the speedo, and I like to watch the road!
    • BeenThroughItAll
    • By BeenThroughItAll 20th Mar 17, 1:13 PM
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    BeenThroughItAll
    Check the clutch yourself.
    Drive car to a hill at 30mph. Put car in fifth and floor the throttle up the hill. IF revs rise and speed does not rise in line with engine RPM, THEN clutch is slipping, ELSE you have another fault.
    • mcpitman
    • By mcpitman 20th Mar 17, 1:13 PM
    • 521 Posts
    • 359 Thanks
    mcpitman
    Turbo lag doesn't explain the engine RPM rising whilst vehicle speed doesn't increase, though.
    Originally posted by BeenThroughItAll

    True, but does explain the comment made by the OP;
    "The car is speeding up, but it seems as though there is a half second delay after using the throttle."


    Truth is, never of us will know unless we either drive the car or see a video of symptoms, so just trying to add a fresh view on the debate.
    Life isn't about the number of breaths we take, but the moments that take our breath away. Like choking....
    • Geodark
    • By Geodark 20th Mar 17, 1:15 PM
    • 730 Posts
    • 456 Thanks
    Geodark
    Turbo lag doesn't explain the engine RPM rising whilst vehicle speed doesn't increase, though.
    Originally posted by BeenThroughItAll
    Exactly, if the revs go up not in proportion to speed increase and then the engine catches up - it points to clutch slip.
    • Aylesbury Duck
    • By Aylesbury Duck 20th Mar 17, 1:26 PM
    • 1,145 Posts
    • 1,427 Thanks
    Aylesbury Duck
    I'm another one who believes this to be clutch slip. Had the same symptoms on my car after 120k miles. As BeenThroughItAll suggests, there is a simple test for clutch slip. If you're not near a hill, you can do a similar test (on a clear road) by changing to a high gear at low speed and trying to accelerate. If the clutch is slipping, you'll hear and feel the engine revs rising, then delayed acceleration. You may even notice a hot smell in the cabin.
    • marcarm
    • By marcarm 20th Mar 17, 1:50 PM
    • 673 Posts
    • 814 Thanks
    marcarm
    Just been out for a drive and got my young lad to take a video which is uploading so will post soon.

    Looking at the revs, it seems as though my driving style was leading me to accelerate at 1500/2k revs which is when the issue was happening, but when I started changing gear at higher revs it didn't seem to happen so much. As a previous posted said 'Are you changing gear and hitting less than 1500-1700rpm when new gear is engaged? If so, you are labouring the engine too much and not capitalising on the torque provided by the engine.'

    When using the throttle lightly and accelerating slowly it was fine, it was just when trying to get away quick.

    Not sure how much you will be able to see on the video but from this it does seem as though I need to change my driving style slightly.

    Edit, just watched the videos and you don't seem to be able to pick much up from them, but have posted them anyway. Even though I was replicating the problem it doesn't seem to have come up in the video. Excuse the baby gurgling and chatting to my other child

    At about 15 seconds in the first video it is clearest

    https://youtu.be/FsCPLxJIvgE
    https://www.youtube.com/watch?v=Azy0YQI4n0E
    https://www.youtube.com/watch?v=QZKyhgITw3g
    Last edited by marcarm; 20-03-2017 at 2:02 PM.
    • Aylesbury Duck
    • By Aylesbury Duck 20th Mar 17, 1:54 PM
    • 1,145 Posts
    • 1,427 Thanks
    Aylesbury Duck
    When using the throttle lightly and accelerating slowly it was fine, it was just when trying to get away quick.

    Not sure how much you will be able to see on the video but from this it does seem as though I need to change my driving style slightly.
    Originally posted by marcarm
    And get a new clutch. All the symptoms you describe, and when they manifest themselves, point to a slipping clutch. In its early stages of wearing out, a clutch will only slip when it's under load. So accelerating gently won't make it slip. That's why we've suggested testing it on a hill or by trying to accelerate quickly in a higher-than-normal gear.
    Last edited by Aylesbury Duck; 20-03-2017 at 1:56 PM.
    • BeenThroughItAll
    • By BeenThroughItAll 20th Mar 17, 2:22 PM
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    BeenThroughItAll
    That's the clutch slipping, going by the first video. Didn't watch the others.
    • marcarm
    • By marcarm 20th Mar 17, 2:23 PM
    • 673 Posts
    • 814 Thanks
    marcarm
    That's the clutch slipping, going by the first video. Didn't watch the others.
    Originally posted by BeenThroughItAll
    Thanks, but not what I wanted to hear

    Trip to the garage soon then
    • Aylesbury Duck
    • By Aylesbury Duck 20th Mar 17, 2:26 PM
    • 1,145 Posts
    • 1,427 Thanks
    Aylesbury Duck
    Yep, clutch slipping, clear as anything.
    • marcarm
    • By marcarm 20th Mar 17, 2:29 PM
    • 673 Posts
    • 814 Thanks
    marcarm
    I now concur, been out to the car and started it. Selected 3rd and lifted the clutch and it didn't immediately stall.

    Did it a few times and each time was the same. On a couple of occasions I managed to get it near the top before the car stalled.

    Pricy job or not?
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