Monster MotorsportEM Tuning
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  1. #1
    Toxik-Signal's Avatar
    Andy

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    Revs rising by themselves sometimes on idle?

    Basically what happens is I'll be sitting at some traffic lights (in neutral) and the engine revs will rise slightly (by about 200-300) and then just sit revving higher than usual. I find this starts to happen just after putting my clutch in. Anyone know why my car is so revvy?

    It's a 1.9 TDI (130).
    Last edited by Toxik-Signal; 1st August 2007 at 10:24.

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  3. #2
    6th Gear

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    over-revving problems on my s3 were due to a mixture of a broken pre-cat lambda and a dodgy throttle potentiometer (only applicable if yours is DBW). Does vag-com say anything?


  4. #3
    Toxik-Signal's Avatar
    Andy

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    I don't have vag-com but this doesn't happen all the time, just every once in a while. It doesn't sound like it's having trouble or anything - just sounds like the accelerator is being touched ever so slightly :S

  5. #4
    3rd Gear

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    Mine does this when i drop the clutch a little to late, i think its to stop you labouring the engine and stalling it because i also get a surge forwards if i dont give it enough power when letting the clutch out

  6. #5
    Sandip's Avatar
    6th Gear

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    i think your throttle needs a clean or you need a new maf, give your throttle a quick clean see if it make any difference
    3.2 V6 with Custom Code VVT Attack Software


  7. #6
    Toxik-Signal's Avatar
    Andy

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    Cheers, might sound like a dumb question but how do I clean the throttle?

  8. #7
    vrbob's Avatar
    Thats no Moon, Thats a space station!

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    Here is the thread i used when cleaning my throttle body

    Throttle Body Clean.
    Audi S3 8L BAM 225 2002 - Ming Blue : Silver Heated Leather, Armrest, RNS-E - Bose, Alloy Mirrors, 18" RSTT`s, Sunroof, Cruise, AutoDim Mirror & Usual S3 Extras.
    Mods : Badger 5 Stg 2 Custom Map, FMIC, 3" DP & 200 Cell Cat, 007P, Jetex Filter & 80mm TIP & Heatshield, Complete LED Kit, Gen VW Aero Wipers, Full Powerflex Kit, R32 RARB, AP Shocks & Springs, 15mm Front & 20mm Rear Spacers, BB Uprated Actuator,
    N249 Delete & Catch Can, AP TVR 4Pot Brakes & DS2500`s, Sachs Carbon/Kevlar Clutch

  9. #8
    Reverse Gear

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    I posted the exact same question about a month ago and alot people confirmed their S3 does the same thing, one guy compared an idle S3 to a purring tiger!

    Looks like its just one of those things, along with the on board computer not registering the door is shut if you leave your car out in the sun....

    I just ignore it now.

  10. #9
    6th Gear

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    have to say that mine never does it. It did, but i got it fixed. Idle is rock solid and always between 800-900 RPM when warm.

    I wouldn't have thought that replacing the MAF would make the slightest bit of difference - at idle the ECU is on an idle map, and isnt bothered about measuring airflow or boost - it knows idle airflow values.

    The most likely culprits are those responsible in the idle adaptation - i.e. lambda and coolant sensor. Idle speed is dependant on information on these to ensure that the idle mixture is adapted to the engine temperature AND the output exhaust gas. If any of these are intermittent, then the idle mixture will be wrong and you'll get fluctuations.

    another part could be the throttle potentiometer on DBW cars. If it's sending incorrect information about the accellerator pedal position, the ECU could be continually switching between idle and accelleration maps.

    Other than the above sensors, you have the obvious physical factors. These factors are those that would affect either the fuelling or air getting to the engine, such as clogged throttle body or air leaking out before it reaches the engine.
    Last edited by madvw; 2nd August 2007 at 13:10.


  11. #10
    Toxik-Signal's Avatar
    Andy

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    Dunno if this'll help or not but occasionally when starting the car (foot off the gas), as soon as the engine starts it revs up to about 1500 briefly before dropping back down to idle speed. Is it related? The last thing I do before switching it off is let it idle for about 45secs (turbo).

  12. #11
    jojo's Avatar
    S3 Drift King!

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    If the revs rise on cold startup, then it most definitely your temp. sensor, had this problem on my Passat TDI. Not too sure if it's related to your other rev problem though...



    99' Audi S3(APY) - Brilliant Black Click>>>Going Sideways vid!
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  13. #12
    aidank1981's Avatar
    1st Gear

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    i had this before i changed my MAF, never had it since so assumed it was the culprite?
    Audi S4 Black on Black. 1999(T)facelift, Aluminium Mirrors, KW Varient 3 coilovers, AmD remap, uprated D/V's, 315bhp375Lb/ft torque, milltek down, 100cpsi cats an back, S4 B6 18" Oem runnin toyo T1-R's. Rs4 B5 front brakes still to fit...


 

 

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