1988 Gti 16v Rough Running Issues - Found a couple of things - Need help!

Discussion in '16-valve' started by Gazzmondo, Feb 18, 2016.

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  1. Gazzmondo

    Gazzmondo Paid Member Paid Member

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    I've had the Timing belt and tensioner changed, but my car was still running very lumpy and it's taking a while to start. So tonight I started to have a good look under the bonnet. Checked the ISV was buzzing and vibrating - and it was. Took it off anyway and gave it a good blast with WD40 to get some of the gunge out. One of the sensors on the back of the engine (passenger side) had a poor connection, so fixed that. Then decided to check the hoses and the throttle body. Discovered that the air intake angled hose, has a hole in it. Also found an unconnected fabric hose which looks like it goes somewhere next to the metering head? Found an unconnected light grey plastic pipe, so figured they fit together as I couldn't find any other lose pipes/hoses? I've attached the photo's of the hole in the air intake hose - would this small hole have a effect on the idling and general performance. Also the same question about the unconnected fabric hose I found, and what is this hose for?

    THE HOLE...
    [​IMG]

    THE UNCONNECTED PIPE I FOUND...
    [​IMG]

    CONNECTED IT UP...
    [​IMG]
     
    Gazzmondo, Feb 18, 2016
    #1
  2. rubjonny

    rubjonny Administrator Staff Member Admin

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    you should have 2 electric valves behind the airbox, both with vacuum connections (get a T piece if you need to split that pipe) the smaller metal one is the cold throttle enrichment valve and triggers the 5th injection if you boot it cold. it should have a 2 pin plug with black and white wires to it. The larger plastic one is the over-run cut-off valve and is there to catch the revs if you lift off at high rpm to stop the engine cutting out. this one should have a black/yellow and brown/black wire.

    you may also have pipework to the warm air flap in the airbox, I would just bin all that off as it doesn't really do anything in our climate

    any vacuum leaks will mess up the idle so get yourself another boot asap, you can attempt to patch it up for now but its in a tricky location
     
    rubjonny, Feb 19, 2016
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    Gazzmondo likes this.
  3. KWAK

    kwak New Member

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    Yes. The engine pulls air into the engine. Aside from the ISV, all of the air must be metered, it must flow past the metering plate. This is what controls the mixture, matching the fuel to the amount of air. An extra hole between the metering plate and the engine allows unmetered air to enter. This will cause the mixture to be lean.
     
    kwak, Feb 20, 2016
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  4. Gazzmondo

    Gazzmondo Paid Member Paid Member

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    Made another discovery - The injector seals are past their best. Sprayed WD40 onto them and you can hear them hissing. So air is escaping? How do I replace them? Tried pulling them straight out but they're in pretty firm. Any suggestions?
     
    Gazzmondo, Feb 20, 2016
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  5. BEN_S

    Ben_s Forum Member

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    They just pull out with a good wiggle. A bit of penetrating oil or wd40 left to soak in might help. Be a bit careful though as sometimes the injector will come out leaving the seal in the head. You don't really want to drop the seal inside the head trying to get it out lol. I'm not sure if the hole is big enough for it drop inside though

    Sent from my GT-N7100 using Tapatalk
     
    Ben_s, Feb 21, 2016
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  6. BEN_S

    Ben_s Forum Member

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    Oh, and some self amalgamating tape might work as a temporary fix for the hole in the intake?

    Sent from my GT-N7100 using Tapatalk
     
    Ben_s, Feb 21, 2016
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  7. Finite

    Finite Paid Member Paid Member

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    Everyone should have some self amalgamating tape in the tool box fantastic stuff :thumbup: I have a temporary fix that's becomes semi permanent due to the properties of this tape lol.

    \Off Topic

    I have some relations in Bend & Portland Oregon.
     
    Last edited: Feb 21, 2016
    Finite, Feb 21, 2016
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  8. Gazzmondo

    Gazzmondo Paid Member Paid Member

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    Thanks people! :thumbup:
     
    Gazzmondo, Feb 21, 2016
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  9. Gazzmondo

    Gazzmondo Paid Member Paid Member

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    Just ordered some of that tape: Screwfix 3.99
     
    Gazzmondo, Feb 21, 2016
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  10. KRONEY

    Kroney Forum Member

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    Whilst you're there check the vac lines behind what I assume is a heat shield in front of the bulkhead. Roasting tray looking thing. I found a huge split back there when I was digging around in mine. It wouldn't have been spotted had I not got in a massive strop and decided to replace the whole lot.
     
    Kroney, Feb 22, 2016
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  11. BEN_S

    Ben_s Forum Member

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    I replaced all of mine too. I bought some black silicone vac hose and some plastic t piece connectors from eBay. Nice and cheap and much better than dried out original rubber

    Sent from my GT-N7100 using Tapatalk
     
    Ben_s, Feb 22, 2016
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  12. Gazzmondo

    Gazzmondo Paid Member Paid Member

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    Dodgy injector seals...
    [​IMG]
     
    Gazzmondo, Feb 22, 2016
    #12
  13. BLIS

    blis Forum Member

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    Love the stuff :)
     
    blis, Feb 22, 2016
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  14. Gazzmondo

    Gazzmondo Paid Member Paid Member

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    Absolute swine to get out, these little buggers. Had to use a claw hammer to leaver them out as I was losing too much skin from my knuckles and nearly pulled my spine out, trying to yank them free.
    I think they're a bit dirty...
    [​IMG]
     
    Gazzmondo, Feb 22, 2016
    #14
  15. BEN_S

    Ben_s Forum Member

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    At least they're out [emoji106]



    Sent from my GT-N7100 using Tapatalk
     
    Ben_s, Feb 22, 2016
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  16. Gazzmondo

    Gazzmondo Paid Member Paid Member

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    Right! Replaced the brass & plastic injector inserts, rubber seals and rocker cover gasket as it was leaking. Haven't had a chance to replace the injectors themselves yet. Patched a hole in the air intake rubber which connects to the throttle body until I can get a new one. Put everything back together. Fired it up, but it took a couple of turns of the key. Car was responsive to the accelerator pedal straight from cold, but as soon as the car started to warm up, it continued to run really rough, and splutter when you hit the gas pedal as it did before?
    Any ideas?
    I've had this car six months and it's moved about 15 miles since I got it home. Beginning to pull my hair out now.
     
    Gazzmondo, Feb 29, 2016
    #16
  17. rubjonny

    rubjonny Administrator Staff Member Admin

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    did you check the injector spray patterns while they were out? with all the air leaks you have fixed though chances are it needs the base idle and co reset so I'd do that once you have confirmed the injectors are working ok.

    if its still bad after that then ideally you want to get the system, control, warmup and residual pressures checked to make sure the metering head and wur are all ok
     
    rubjonny, Feb 29, 2016
    #17
  18. Gazzmondo

    Gazzmondo Paid Member Paid Member

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    Didn't check the injector spray patterns. What's the best way?
     
    Gazzmondo, Feb 29, 2016
    #18
  19. rubjonny

    rubjonny Administrator Staff Member Admin

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    rubjonny, Feb 29, 2016
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  20. Gazzmondo

    Gazzmondo Paid Member Paid Member

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    Thanks!
     
    Gazzmondo, Feb 29, 2016
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