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Revs not coming down?

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  • 26-09-2020 1:02pm
    #1
    eamon11
    Site Banned Posts: 518 ✭✭✭


    hello all,

    it's a 1.4 petrol engine. When I revi it's a tiny bit slower to respond. When I let go the accelerator, it takes around 2 seconds before it responds. This is problematic when changing gears as when I press clutch, instead of engine revs decreasing, they increase. Idle is sometimes a tiny bit erratic too. Sometimes at 800, sometimes at 1000 or 1200. Have checked and changed a few things. Cable is good and responds immediately moving the throttle body part. Used carb cleaner inside throttle while engine running.Gave it a full service including new air, oil filters. Does anyone know what the problem might be?


    Thanks a lot


Comments

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    #2
    Atlantic Dawn
    Registered Users Posts: 81,154 ✭✭✭✭Atlantic Dawn
    M


    If you took the car on a long drive does it happen the entire time or just in the first 5 minutes or so?


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    #3
    eamon11
    Site Banned Posts: 518 ✭✭✭eamon11


    the entire time, it's and constant, doesn't matter distance or engine temperature.


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    #4
    barneygumble99
    Registered Users Posts: 4,119 ✭✭✭barneygumble99


    It might help if you told us what car , year etc??


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    #5
    ice.cube
    Registered Users Posts: 103 ✭✭ice.cube


    eamon11 wrote: »
    hello all,

    it's a 1.4 petrol engine. When I revi it's a tiny bit slower to respond. When I let go the accelerator, it takes around 2 seconds before it responds. This is problematic when changing gears as when I press clutch, instead of engine revs decreasing, they increase. Idle is sometimes a tiny bit erratic too. Sometimes at 800, sometimes at 1000 or 1200. Have checked and changed a few things. Cable is good and responds immediately moving the throttle body part. Used carb cleaner inside throttle while engine running.Gave it a full service including new air, oil filters. Does anyone know what the problem might be?


    Thanks a lot

    Potentially a dodgy Maf sensor or vacuum leak maybe? Pure speculation though without more detail.


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    #6
    jetfiremuck
    Registered Users Posts: 3,466 ✭✭✭jetfiremuck


    clean the throttle body. be sure to open the throttle plate. a good scrub with brake cleaner and old tppth brush should do the trick and clean the map sensor with electrical contact cleaner, no other spray.


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  • Options
    #7
    eamon11
    Site Banned Posts: 518 ✭✭✭eamon11


    thanks lads,
    could it be the throttle position sensor?


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    #8
    Sonic the Shaghog
    Registered Users Posts: 596 ✭✭✭Sonic the Shaghog


    May be of no use but I'd a Focus one time which had a series of rubber pipes one of which had slight tear and she was sucking in air causing high revs is there anything like that?


  • Options
    #9
    Dirty Nails
    Registered Users Posts: 463 ✭✭Dirty Nails


    eamon11 wrote: »
    hello all,

    it's a 1.4 petrol engine. When I revi it's a tiny bit slower to respond. When I let go the accelerator, it takes around 2 seconds before it responds. This is problematic when changing gears as when I press clutch, instead of engine revs decreasing, they increase. Idle is sometimes a tiny bit erratic too. Sometimes at 800, sometimes at 1000 or 1200. Have checked and changed a few things. Cable is good and responds immediately moving the throttle body part. Used carb cleaner inside throttle while engine running.Gave it a full service including new air, oil filters. Does anyone know what the problem might be?


    Thanks a lot


    Carb or fuel injected? Blocked air filter would do that.
    Sorry,see new air filter in it, Even so,take the lid off the air filter & give it a few revs. It could still be a restricted air intake


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    #10
    jmreire
    Registered Users Posts: 8,268 ✭✭✭jmreire


    Can you get a scan done on it, and see what that will tell you? Could save a lot of time trying out different possibilities.


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    #11
    eamon11
    Site Banned Posts: 518 ✭✭✭eamon11


    have scanned it and it shows nothing. it's fuel injected. It's a Chevrolet aveo 2008. Have taken off air breather and tried but no difference. Main problem is the long time lag before anything happens when I take my foot off the accelerator. thanks


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    #12
    jmreire
    Registered Users Posts: 8,268 ✭✭✭jmreire


    eamon11 wrote: »
    have scanned it and it shows nothing. it's fuel injected. It's a Chevrolet aveo 2008. Have taken off air breather and tried but no difference. Main problem is the long time lag before anything happens when I take my foot off the accelerator. thanks

    I would not have much experience with one of them, so can't really help, especially when the scan revealed nothing. Sorry about that. Good Luck in getting it sorted, its a dangerous fault when it wont drop the revs.


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    #13
    The Continental Op
    Registered Users Posts: 6,196 ✭✭✭The Continental Op


    It does sound like a lag in the time it takes the TPS (Throttle Position Sensor) to respond. I've had problems with the TPS before but mine where electrical in the cabling when the TPS just randomly failed and the car went into limp mode.

    I'd also try disconnecting the battery, leave it off all night then replace it in the morning and see how it goes. Might make the ECU reset? Remember you'll need the Radio Code if you do this.

    Wake me up when it's all over.



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    #14
    newirishman
    Registered Users Posts: 270 ✭✭newirishman


    That Chevrolet isn’t exactly a race car. I would think that what you experience is standard behaviour for this car. Especially given its age.

    Old Road Test when it was released:
    https://www.topgear.com/car-reviews/chevrolet/aveo/14-lt-5dr/road-test


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    #15
    eamon11
    Site Banned Posts: 518 ✭✭✭eamon11


    Have unplugged the TPS and it has made no noticable difference to the driving of the car.Battery left disconnected overnight. Throttle body well cleaned. Spring and butterfly flap seams to be springing back ok. Unplugged a few other sensors too to see what happens, including air temp sensor and idle control valve. No difference. Next step may be to remove throttle body completely and take apart and give it a deep clean, but from what I can see it's already been well cleaned up with the carb spray.I will not get into semantics with you Irishman but what's happening is definately not standard behavior, in any car. It is in fact downright dangerous.As regards a top gear review I wouldn't put too much stock in them, it's an entertainment show by actors! thanks for all the replies lads.


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    #16
    The Continental Op
    Registered Users Posts: 6,196 ✭✭✭The Continental Op


    eamon11 wrote: »
    I will not get into semantics with you Irishman but what's happening is definately not standard behavior, in any car. It is in fact downright dangerous.

    If you think about it then its got to be a combined effect. Not the the TPS but the throttle itself has to have some sort problem. If the TPS was as you suggest working with a 2 second delay then the throttle would be fully open 2 seconds before the TPS registered the fact and I don't see the engine working well under those conditions, so I think something must be affection both if they are in fact the root of the problem.

    Wake me up when it's all over.



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    #17
    con747
    Registered Users Posts: 5,771 ✭✭✭con747


    eamon11 wrote: »
    I will not get into semantics with you Irishman but what's happening is definately not standard behavior, in any car. It is in fact downright dangerous.

    Not sure if this helps, found it online.

    Recently I been experiencung high idle at start up and clutching. I change IAC. Plugs and wireds. Nothing worked. Today the high idle became constant. It was a metal bubble flex tube near the IAC unit that goes to the exhaust stuff down behind the motor. It apparently was cracked cause today it broke causing the constant high idle sound like a vacumn. We blocked it off with a stick to get the idle back down to 900 rpm instead of 3-4000 rpm took we can get to auto zone for high temp hose per Chevy dealer. I hope this helps someone cause it was fustrating and costly.

    Don't expect anything from life, just be grateful to be alive.



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    #18
    greasepalm
    Registered Users Posts: 5,252 ✭✭✭greasepalm


    Not sure if same as Kalos but is the elephant trunk from air filter housing to air intake split thus making air sensor having the wrong reading.


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    #19
    eamon11
    Site Banned Posts: 518 ✭✭✭eamon11


    thanks lads, see my last post for issues tried. The elephant trunk hose was indeed cracked which I fixed. However when testing I have tried with no hose at all, or IAC unplugged. Nothing made a difference.


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    #20
    greasepalm
    Registered Users Posts: 5,252 ✭✭✭greasepalm


    Might take a day or 2 self regulate after you fixed the air leak as it might be confused with what was and what is now.


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    #21
    Hellrazer
    Moderators, Arts Moderators, Recreation & Hobbies Moderators Posts: 10,581 Mod ✭✭✭✭Hellrazer


    eamon11 wrote: »

    it's a 1.4 petrol engine. When I revi it's a tiny bit slower to respond. When I let go the accelerator, it takes around 2 seconds before it responds. This is problematic when changing gears as when I press clutch, instead of engine revs decreasing, they increase.

    I think your clutch is slipping.


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    #22
    eamon11
    Site Banned Posts: 518 ✭✭✭eamon11


    I test it in neutral, by moving the throttle lever manually with bonnet up, so this eliminates your theory about clutch. Had a code today intake air temp high. ? anyone know what this means?.


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