Author Topic: Help with troubleshooting low power  (Read 2860 times)

Offline JacksonBrown

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Help with troubleshooting low power
« on: 22 July 2023, 09:54 »
There’s a bit of a long backstory here so I’ll bullet point it to keep it short and understandable.

  • Bought the car in December, was tuned but with no records.
  • At the time, had so much torque it would cause the clutch to slip even when I put my foot down in 5th and 6th.
  • In January slid on some sand and hit a curb, bending my wishbones and brake discs.
  • New wishbones, discs and pads and new wheels.
  • Since returning, car would misfire and stall on idle with a very intense smell of fuel.
  • Full service, including new plugs, no help.
  • Showed conflicting faults on VAG, found a damaged sensor and replaced. Cleared conflicting faults.
  • Still misfiring and stalling, changed PCV on recommendation. No help.
  • Still misfiring and stalling and now showing timing fault. Was recommended new chains but that didn’t make sense to me so I kept trying new mechanics until one agreed.
  • Had tune removed to see if it was messing with my timing.
  • Found sticky solenoid on intake, replaced and misfire fixed.
  • Only fault code showing now is 14916 and P0420, both relating to cat efficiently below threshold.

The car feels low on power, like I’m lacking throttle response and there is still a very intense smell of fuel. My brothers 2.0 Mk6 is quicker. The only recommendation I’ve had since arriving at this part is to take off downpipe and check for blockage or dirt. My instinct tells me it’s throttle related but I’m no mechanic, and I still have this idea in the back of my mind that there may be a vacuum leak.

Anybody have any similar experiences and may have some suggestions? I’d rather not be changing stuff and spending money just to see if it works. Had a bloody GTI for over 6 months and haven’t been able to drive it properly yet  :cry:

Offline willni

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Re: Help with troubleshooting low power
« Reply #1 on: 22 July 2023, 12:07 »
    • Had tune removed to see if it was messing with my timing.
    • Found sticky solenoid on intake, replaced and misfire fixed.
    • Only fault code showing now is 14916 and P0420, both relating to cat efficiently below threshold.

    Did you replace the factory cat with an aftermarket one then remove the map and leave the aftermarket exhaust on?
    Mk7.5 GTI - Performance Pack, DSG, Sunroof, Dynaudio, Pro Nav, Vienna Leather, Climate Windscreen & last of the 3 doors....Many Sets of Alloys...

    Prev - Mk7.5 White Silver, Vienna Leather, Sunroof, Helix Sub, Many Wheels

    Follow my 7.5 build on the forum https://www.golfgtiforum.co.uk/index.php?topic=287596.msg2638666#new or on Instagram https://www.instagram.com/willy_gti7.5pp/

    Offline JacksonBrown

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    Re: Help with troubleshooting low power
    « Reply #2 on: 22 July 2023, 12:30 »
    All parts are factory.

    Offline madstaff

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    Re: Help with troubleshooting low power
    « Reply #3 on: 22 July 2023, 12:48 »
    Smell of fuel obviously points to a fuelling issue which has potentially damaged the cat, hence the efficiency below threshold.

    I would read current fault codes and save a copy of them, clear them all, then go for a drive, rescan for codes and see what you've got then.

    2017 Clubsport Edition 40 #706.

    Urano grey, 3 Door, Manual, Recaros, Brescias, DCC, Nav Pro, Black roof & tints.

    Offline JacksonBrown

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    Re: Help with troubleshooting low power
    « Reply #4 on: 22 July 2023, 16:05 »
    Smell of fuel obviously points to a fuelling issue which has potentially damaged the cat, hence the efficiency below threshold.

    I would read current fault codes and save a copy of them, clear them all, then go for a drive, rescan for codes and see what you've got then.

    Have cleared and driven a few times and these two keep reoccurring. I’m more than happy to slap a new cat on if that’s likely the issue. Could a damaged cat lead to low power? Or I suppose I have a fueling issue alongside a now damaged cat! Wooo!

    Offline madstaff

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    Re: Help with troubleshooting low power
    « Reply #5 on: 22 July 2023, 16:14 »
    Has anyone looked at the live data to see if the lambda sensors are functioning correctly??
    2017 Clubsport Edition 40 #706.

    Urano grey, 3 Door, Manual, Recaros, Brescias, DCC, Nav Pro, Black roof & tints.

    Offline willni

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    Re: Help with troubleshooting low power
    « Reply #6 on: 22 July 2023, 17:00 »
    I was also going to say I'd test the lambda sensors before jumping straight to a new cat.
    Mk7.5 GTI - Performance Pack, DSG, Sunroof, Dynaudio, Pro Nav, Vienna Leather, Climate Windscreen & last of the 3 doors....Many Sets of Alloys...

    Prev - Mk7.5 White Silver, Vienna Leather, Sunroof, Helix Sub, Many Wheels

    Follow my 7.5 build on the forum https://www.golfgtiforum.co.uk/index.php?topic=287596.msg2638666#new or on Instagram https://www.instagram.com/willy_gti7.5pp/

    Offline JacksonBrown

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    Re: Help with troubleshooting low power
    « Reply #7 on: 23 July 2023, 10:39 »
    I’ll see if somebody can check for that. Thanks for the suggestion!