How to tune 8v gti mk2???

Discussion in 'Engines' started by 1982.rpd, Apr 17, 2007.

  1. 1982.rpd Forum Member

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    What are simple ways of tuning a mk2 gti 8v, I've been told to cut holes in the air filter box and there is something you can do with the injectors to make it quicker, any other tips would be greatly appreciated!!!
     
  2. arienol Forum Member

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    What year is the car? Is it mechanical injection (kjet) or efi (digifant) ???

    Camshaft, better exhaust, airbox modification as you mention, ported/polished head, enlarged valves, capacity increase or a 2.0 bottom end which can be bought for peanuts).

    Also, get it set up by someone who knows what they are doing.
     
  3. abf"d mk1 Paid Member Paid Member

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    quite. to make a difference you would notice involves more than making holes and changing injectors.
     
  4. arienol Forum Member

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    Drilling holes in the airbox will make the car sound faster, but in reality it won't be. Its your car though so do what you want with it :)
     
  5. dubst16v Forum Member

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    i found when i had an 8v changing dizzy cap an rotor arm taking the funnel out of the front of the airbox and putting in a k&n panel filter

    didnt make it faster but did help throttle response which was nice
    bang for buck i would think 2.0 bottom end is ur best bet
     
  6. StuMc

    StuMc Moderator and Regional Host - Manchester Moderator

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    If it`s Digifant you could tinker with the air flow meter; Take the black top off and you`ll see toothed wheel and a clock spring. The toothed wheel is clamped by a small clip. Undo this clip, but hold the wheel VERY CAREFULLY! Don`t let it spin or that`ll be the end of your AFM! Let the wheel come back by three teeth and re-tighten the clip. You should now notice much better throttle response and none of the infamous Digi-lag! ;)
     
  7. wcrado Forum Member

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    this sounds cool! how come i've not heard this before? what are you actually adjusting then, just fuel pressure?

    when you say let the whel spin back 3 teeth, do you mean that it will automatically try and spin, and i should just let it go for 3 teeth before re-tightning?
     
  8. StuMc

    StuMc Moderator and Regional Host - Manchester Moderator

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    What ever you do don`t let go the wheel!!! It`s sprung and will want to spin out of your hand, just hold it and slowly let it go back three teeth before re-tightening.
    I`m not sure what it does. It`s not fuel pressure as such, I think your just fooling the ECU into thinking there is slightly more air coming in than there actually is, therefore it`s putting more fuel in. Because it`s just a small adjustment to smooth out the infamous pause in throttle response on Digi engines it doesn`t affect fuel consumption too much.
    Not many people have heard of it. I saw it on some american site a couple of years ago, where the guy had experimented with how many teeth to adjust it by. He concluded that any more than three wouldn`t make any difference, and would in fact make it worse.
    Good luck, and, remember. BE CAREFUL NOT TO LET THE WHEEL GO!!! ;)
     
  9. Mike_H Forum Addict

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    If it's the car in your other post it's a K-Jet car, and you should

    1. sort out the bottom end knocking first!
    2. get the k-jet properly set up by someone like stealth racing.

    To get more than the odd couple of horses you need to change big chunks of the engine - a flowed head, a 2.0 bottom end, and a cam change would all help significantly. A decent quality exhaust (std VAG or a good aftermarket straight through system like supersprint / jetex)

    Where are you based?

    a 2.0 engine should cost you 100 or less.
     
  10. wcrado Forum Member

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    mine doesn't have much lag.... how can i tell if mine is already done? is there supposed to be a load of clear glue holding the black cover down on the afm?
     
  11. 2dubnick Forum Junkie

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    do you just use the force to take the black top off the afm?
     
  12. drunkenalan Paid Member Paid Member

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    not quite force, more like lever it gently, it does come off fairly easy,
    If you crack it make sure you seal it properly as i had one that was dirty inside and was f000ked on a car i aquired as a poor runner.one 2nd hand afm later i as a couple of pounds richer as the guy i got it off bought it back + a little bit for time,parts etc. it hadn't been adjusted just damaged probably by some one changing the airfilter.
     
  13. wcrado Forum Member

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    so how do i tell if mine has already been done or not?
     
  14. 2dubnick Forum Junkie

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    cheers!
     
  15. wcrado Forum Member

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    okay i did it anyway, seeing as you lot ignored me!

    INSTANTLY noticed the difference.

    i didn't think mine was laggy, but what i noticed straight away was i don't need to plant my foot anymore! i didn't even realise i was doing it, but everytime i was changing gear my foot was welded to the floor waiting for the engine to catch up. Now i barely have to stroke the pedal when i change gear and she pulls hard! feels like it goes better at full beans too.

    also, i fitted a cone filter the other week (insert max power joke here) just to get some extra push, and although it felt a bit better, it did open up a big flat spot at about 3.5k rpm. I guess it must have been running a bit lean due to the extra airflow (something i thought the AFM would sort out itself), this has totally cured it.

    I'm well chuffed- much better throttle response, smoothed out the power curve and got rid of flatspots, all the benefits of a chip!

    which brings me another question.... i was going to order a blitzchip soon, as people have had good results with them. is there any point now i've done this mod?
     
  16. Phil. Forum Junkie

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    Glad to hear it worked, I was going to try the AFM trick ages ago after reading it on VW vortex.

    I have a blitzchip'd 8v so i'll do the AFM mod tonight and report any findings.
     
  17. 2dubnick Forum Junkie

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    yep iv got a blitzchip but im going to do this anyway I will also post up the results
     
  18. Phil. Forum Junkie

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    Agree with wcrado, I was out playing with the AFM tonight. Here's what you'll see when you open it up.

    [​IMG]
    phonecam so not a great pic.

    I didn't think my car was down on power, it made 113bhp and 127lbs last week which isn't bad for a 17yr old car with an exhaust and an unproven chip. BUt recenty I just felt it was lacking a bit of responsivness.

    I moved the spring out that engages the wheel with my finger (just as carl loader says, no need to undo the 7mm screw) carefully moved the wheel anti-clockwise 3 clicks and to cut a long story short it now drives like a K-Ket :lol: Much smoother at part throttle and alot more responsive. Took it for a quick spin roumd the block and I can't believe the difference. :thumbup:
     
  19. 2dubnick Forum Junkie

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    cheers for the photo, I wasnt sure what to expect when i open it.
     
  20. rubjonny

    rubjonny Administrator Staff Member Admin

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    I have to add that fiddling inside the AFM is the LAST thing you should do before you have tried everything else. It may be you are covering up a problem elsewhere. What you are doing is 'fooling' the ecu there is more air flowing in that there actually is, therefore the ECU is chucking in more fuel.

    The reason this works for you may be that the resistance values in the MAF have changed due to worn out contacts, or you have an airleak somewhere else which is leaning out your mixture. One place to check for problems is the vacuum lines from the inlet, especially the one that runs to the fuel pressure regulator. If these are perished then not only will you have an airleak, but when you floor it the FPR will be slow to respond and supply even less fuel, making the problem worse!

    Check out my shiny new recently stickied digifant tuning post ;)
     

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