MK3 16v GTi seems sluggish

Discussion in '16-valve' started by nickh89GTi, Mar 17, 2009.

  1. azur Forum Member

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    TBH mate.... you don't really want to be doing to much driving around in 4th gear @ 2000 rpm with an ABF... and accelerating from that point. It Puts the engine under unecessary strain, especially the crankshaft and big end bearings.

    not enough air can enter the cylinders on 16v's... and the throttle body is barely open.

    The other problem is that the spark plugs tip temperature remains low at low engine speeds.

    Below 500 degrees at the tip and its in the fouling region where it can't burn off carbon and combustion deposits.... needs to be above 500 degrees to be self-cleaning

    This might explain the sooty ends you saw (dry fouling) and the oily mess (wet fouling)

    16v's run nicely around 2500-4000 if you are just pottering around. Around 3000 rpm is nice for cruising

    Your IAT sounds fine.. when the engine and car has been sat idling for a while all the engine bay heat will radiate into the airbox so late 40's sounds about right.
     
  2. nickh89GTi Forum Member

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    Just done the readings with the lambda plugged in.

    Outside temp 23*C
    Inlet temp 44*C - ECU/VAGCOM
    Water Temp 90*C - Gauge
    Water Temp 90*C - ECU/VAGCOM
    Inj Timing - 2.55ms
    ECU Voltage - 13.9
    Lambda readings flicking between 0.02V and 0.80V

    Hopefully someone can understand these readings better than i can.

    Thanks for all your help guys
     
  3. Matt82

    Matt82 Forum Addict

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    with the lambda plugged in there is less fuel being put in (injector timing) and for the lambda figure to cycle like that is normal too
     
  4. azur Forum Member

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    a lambda reading of 0.80 would indicate the engine is running rich no? Isn't 1.0 the value for a Stoichiometric AF ratio at idle.

    would mean the hole has nothing to do with it anyway.

    Can you post a video of this hesitation mate... would be really helpful.
     
  5. nickh89GTi Forum Member

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    So would you say all those readings look normal to you? Guess some of this may be me thinking the worse :lol:. So the black plugs maybe caused by what azur said in his post about the tip of the plugs not getting hot enough to clean themselves hence black soot build up.

    How quickly would the black soot build up on the plugs?

    Also how long does it take for all yours to get up to 90*C on the temp gauge from cold in the mornings?
     
  6. nickh89GTi Forum Member

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    **bump**

    Hopefully my chip will be here at the end of the week but am unsure whether to put it in yet.
     
  7. Matt82

    Matt82 Forum Addict

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    mine takes about 3 miles to get to 90* in this weather.

    what spark plugs do you have? if they are the wrong heat range they wont self clean

    how many miles does it get per tank?
     
  8. nickh89GTi Forum Member

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    Thats about the same as mine then which is good to know as i couldn't remember how long my old mk3 used to take to warm up.

    Off the top of my head i think they are these BKUR 6 ET-10 NGK which i got from Trade Parts Specialist so hopefully they should be the right ones but i will check when i finish work as haven't got my car with me today.

    Think i got about 330 miles to 50 by the end of last week. Fuel was 101.9 when i put it in which would have given me 49litres so about 10.8 gallons.
     
  9. Matt82

    Matt82 Forum Addict

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    sounds close to right. was that all motorway or mixed?
     
  10. nickh89GTi Forum Member

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    No motorway miles, its only B Roads to work and around town. Its a 55litre tank isn't it on these.
     
  11. tshirt2k

    tshirt2k Forum Junkie

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    That dont sound too bad. Have you thought, your driving style may be causing the car to knock when labouring at low rpm' (4th gear 2000rpm) which will retard ignition and affect power?? My car would judder at low rpm also. If you want to accelerate from that area it would be better to change down a gear or two.
     
  12. nickh89GTi Forum Member

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    Its more when i use third gear after some one has pulled into a junction in front of me. Maybe i should drop down into second. Its all fine after 2.5k, maybe it is just my driving style, used to the 8V torque of a mk2.
     
  13. Matt82

    Matt82 Forum Addict

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    youre doing well then. mpg seems good but im suprised theyre still black

    i think you may just have to accept the mk3 just isnt that quick lol ill try n get a video of mine going through the gears so you can see if its comparable
     
  14. nickh89GTi Forum Member

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    Yes please Matt if you don't mind. I don't know why they are black either. I will check them again in a couple of days see what colour they are then. Otherwise i don't have a clue [:s]
     
  15. Matt82

    Matt82 Forum Addict

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    ill get that sorted

    OMG though, since ive done that last vac leak im getting truely heroic MPG. i can cane it to work. normally id get just over 40 if i took it easy, today i caned it a few times and still managed to get 43mpg

    also, when off the throttle in traffic it used to jerk as the revs went below 2krpm, now its smooth. i suppose its stopping the fuel completely, maybe

    ill vagcom it tonight too
     
  16. azur Forum Member

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    Sounds like it mate... really got to keep 16v's wound up as i said in an earlier post... 8v's reach peak torque @ 3000 rpm... and the 16v is not till 5500-6000 rpm... and they are a lot heavier than mk2 8v's as well.

    I got a little more bottom end with an opened up airbox, bored throttle body and chip... was less restricted.

    Glad you might have sorted the problem anyway. they are good cars...
     
  17. nickh89GTi Forum Member

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    Man i want matt's valver just seems to be getting stronger and stronger with age and MPG just seems to be getting higher and higher. As yours is so healthy matt can you take the same readings from VAGCOM as i posted yesterday please mate.
     
  18. Matt82

    Matt82 Forum Addict

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    time to get a video up. will need super slow motion otherwise the speedo will just be a blur
     
  19. nickh89GTi Forum Member

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    Take it for a cane with the laptop plugged in. Bet you get the "danger to manifold" warning :lol:

    Can you get those readings for me if you vagcom it later on mate.
     
  20. nickh89GTi Forum Member

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    Just had a look at my sparks again after driving into work this morning. They are still a normal colour so when they were black and sooty it must have been from azur said where the tips hadn't been getting hot enough to self clean from short journeys.
     

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