Golf Mk2 20vt

Discussion in 'Members Gallery' started by jshep73, May 22, 2019.

  1. jshep73 Forum Member

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    Went back to Badger 5 last week to try and get to the bottom of my limp mode (only 5 psi of boost) issue.

    ZX1.jpg


    Once again it is an issue with the throttle pedal, the car idles at 1000rpm which I now know is not normal. There is no fault code, but Bill worked out that if you lift the throttle toward you the revs drop to 800rpm and the car boosts as usual. But once you start revving and eventually come off the thottle it goes back to idling at 1000-1200rpm. Bill tried an ignitron ECU which does show a throttle issue. It's as if the default 'off' is not correct and you need to pull the throttle with your foot. The throttle body was reset and it is still doing it. Map was when cleared from my standard ECU and a new one added. Car boosts great now upto 15psi but still has the high idle.

    ZX3.jpg


    Car made 230bhp and 235lb/ft:

    ZX4.jpg

    Very happy with how the car goes now. The power delivery is smooth and doesn't spin tyres for fun anymore!

    When I got home I plugged in my old throttle and it does exactly the same, high idle but goes staight to 800rpm if you pull it up. I kinda refuse to believe that I have 2 throttle pedals that are faulty. Bill suggested it may be the throttle wiring such as a bad ground. Will be looking into this soon.

    I am refurbing my RM's at the moment so bought some Goodyear Eagle F1's for my steelies. Fantastic tyres!!!

    Wheels are back from powder coaters. I have had a go at polishing the lips myself which is such a PITA. Probs about 1.5 hours on each lip at the moment! Close to just bolting them all together soon though...

    ZX5.jpg

    I'm not very productive in 30 degree heat either. Hate it infact!!!

    MOT this week aswell... comes round so quick

    If anyone has any ideas about my throttle issue please shout out

    Cheers all
     
    Vinnie, dodgy and cupracraig like this.
  2. cupracraig

    cupracraig Paid Member Paid Member

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    ahh its always a bad ground! should be simple enough to check through, but best of luck with that!

    Love the RM's, 1.5" lips front and 2" on the rear?
     
  3. Tristan

    Tristan Paid Member Paid Member

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    Must be something with the way it's mounted in the car?
     
  4. jshep73 Forum Member

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    Oh yeah forgot to say the pedal was over to the right abit too much and was touching the plastic on the carpet when pressed. It was an idea that this could confuse the pedal and cause limp mode. But I have since removed the fusebox and re-drilled the bracket and moved the pedal over about 2cm to the left and still having the issue
     
  5. jshep73 Forum Member

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    Yes indeed, perfect sizes in my opinion!
     
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  6. Savagesam

    Savagesam Moderator Staff Member Moderator

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    What a pain in the arse! I hate issues like this.

    Car looks great. Not an RM fan personally, leave them off [:D]
     
  7. jshep73 Forum Member

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    ***Brain can not compute not liking RM's***

    :o
     
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  8. cupracraig

    cupracraig Paid Member Paid Member

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  9. dodgy

    dodgy Paid Member Paid Member

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    Possible resistance from solder joints in the loom?
    Sure my mate had this on a mk6 golf where garage replaced pedal and plug was broken so spliced new one on?
     
  10. jshep73 Forum Member

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    Thanks Dodgy, great suggestion! Car idled at 800rpm in the donor car so I am convinced it is wiring since the conversion
     
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  11. Mk2daz

    Mk2daz Paid Member Paid Member

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  12. dodgy

    dodgy Paid Member Paid Member

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    Was definitely different pedal (well control box) between engines on the caddy mk2, petrol and diesel and turbo diesel from memory all used specific ones.
     
  13. jshep73 Forum Member

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    Cheers fellas, I actually have 3 pedals now which are the correct part number - 1J2 721 503C

    All do the same thing, high idle but goes straight to 800rpm if you lift the pedal

    I plan on having a good look and doing some testing next week
     
  14. dodgy

    dodgy Paid Member Paid Member

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    Do you have clutch switch fitted?
    Even on the polo 1.2 we have it did odd idle things when switch broke, high and hanging idle.
     
  15. jshep73 Forum Member

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    I didn't know what a clutch switch was but just googled and looks the same as a brake switch. No I don't have one... what do they do?
     
  16. Tristan

    Tristan Paid Member Paid Member

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    It tells the ecu when you have the clutch pressed, usually stops the engine revving in that instance.
     
  17. Savagesam

    Savagesam Moderator Staff Member Moderator

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    I’ve never had an issue but have seen quite a lot of people with that issue at the moment.
     
  18. dodgy

    dodgy Paid Member Paid Member

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    I'm fitting a microswitch on my mk2 to act as this,
    The audi A4 we had also had switch trouble and it would idle high plus the cruise control didnt work, new switch and all sorted, polo would hang at 1100 then drop to normal when at a junction or traffic lights.
    Know you have a value pointing to the throttle pedal, but may be worth having a look at the clutch one too.
     
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  19. jshep73 Forum Member

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    Ok this is all news to me. Do all 1.8T engines have a clutch switch? Maybe I did have one on the donor and the lad that did my loom removed it

    Feels like I'm barking up the wrong tree though
     
  20. Finite

    Finite Paid Member Paid Member

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    Not sure about AGUs probably not, but the later AUM AUQ definitely have them. As far as I knew they were essential for cruise control.
     

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