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Thread: 2.0l 16v problems when hot

  1. #1

    2.0l 16v problems when hot

    I'm having one last go at solving this on my son's car. Hoping someone has solved a similar issue.
    Car starts and runs perfectly when cold. When the water temp reaches 80 degs small idle surges start happening. This becomes rough running. Once up to full temp he says its almost undrivable. The engine will run ok at high revs but is too erratic to drive normally. When sitting at idle at full temp it runs rough but with occasional moments of smooth running for a few seconds. Have wiggled everything to check for obvious poor connections etc.
    Replaced Lambda, isv, coil, all leads. Checked plugs. Checked and repaired all air leaks. There were some solits in the air intake. Checked maf. Checked mixture, timing.
    Next thing to try i think is the wiring for the lambda. Do the wires go straight to the ecu? If so what pins on the plug so i can check continuity.
    Any ideas other than that?
    Cheers

  2. #2
    ⋆⋆ CF Member ⋆⋆ easypops's Avatar
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    ISV Idle Stabilisation Valve plus the Throttle Potentiometer.
    The ISV gets clogged up and can possibly be revived with a bit of cleaning/lubrication. Many years ago i had a similar issue eventually tracked(by luck) to the wiring plug for the throttle potentiometer.
    Plenty written on this issue previously but the lack of pictures might make some of the old threads a bit useless
    95 Classic Green Storm
    95 Flash Red VR6


    For those who understand, no explanation is needed.
    For those who do not understand, no explanation is possible

  3. #3
    ⋆⋆ CF Member ⋆⋆ easypops's Avatar
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    95 Classic Green Storm
    95 Flash Red VR6


    For those who understand, no explanation is needed.
    For those who do not understand, no explanation is possible

  4. #4
    Thanks very much. Isv is new and have checked for broken wires on the tps as that is a common problem. I think the sensor must be ok as all is good up to 80 degs . All good suggestions though . Thanks.

  5. #5
    ⋆⋆ CF Donator ⋆⋆ Keyo's Avatar
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    At this point I would call Vince at Stealth racing and have a chat.

  6. #6
    ⋆⋆ CF Member ⋆⋆
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    When running rough you could pull each lead off in turn to see if it’s cylinder related?

    A good cylinder would see the idle worsen
    Last edited by Dox; 3 Weeks Ago at 12:33 AM.

  7. #7
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    Got to be temperature related right, so old wiring breaking down when it gets hot, or a temp sensor. Can't remember what the temp sensors are on the KR, but think there's three on the side of the head that often cause probs? Google it and see.

    Might be worth un-wrapping the engine loom and cleaning it up looking for breaks/damage etc.

    You say you've checked the timing, but do you mean static or dynamic? Have you put a light on it to see what the timing is doing when it is idling rough? When was the cam chain last changed? Could have stretched causing issues if it's a high miler.

    No guarantee on 'new' ISVs in my experience either, best thing you can do is test it on another vehicle if there's another 16v owner in your area

  8. #8
    ⋆⋆ CF Member ⋆⋆ vw rule's Avatar
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    To be honest this could be anything from electrical including distributor or fuel system.

    Have you checked the thermal transmitter also known as the coolant temperature switch, as they can break up/burn out and cause the engine to flood from cold, or can cause problems once engine is up to running temperature.
    I think the Lambda sensor is partly on the same circuit as the fuel governor/pressure regulator, and coolant temperature switch.

    A faulty hall sensor in distributor can cause running issues, which also can be heat related i.e up to running temperature, plus the ECU needs to see correct signal from hall sensor, as it confirms the engine is rotating, and I think sends pulse signals to coil.
    Have you checked condition of distributor cap and rotor arm ?

    The ECU has a connector plug with 35 terminal pins, terminal 12 is to fuel relay, terminal 7 is to Lambda sensor I think, which is also linked in circuit to the fuel governor/pressure regulator.


    Si
    Had MK2 1.8 Scirocco Scarla 1998 to 2002
    had it lowered on original wheels,
    K&N air fitler and Janspeed exhaust system.

    Now have 94 M reg Corrado 2.0 16v since 2002 still got it, been off the road now since early 2015
    hoping to get it finished this year.

    Also have a 2015 Seat Ibiza TSI i-tech as my daily driver. Plus I'm on The SEAT Forum.

    Link to 16v torque settings & ECU pin locations.
    http://the-corrado.net/showthread.ph...fuel-pressures

  9. #9
    Thanks. Lots of useful info. Going to go down the temp sensor road. Only 2 by dizzy. Think one is fan sensor. One to guage? Also one bolted to top left of engine. Also will check wiring from new lambda now i have some pin numbers. I have stopped him just buying stuff hoping it will fix it. Trying to be more methodical. New dizzy cap, rotor, coil and leads. Pulling each plug lead makes no odds so pretty sure its fueling so ecu getting wrong into from somewhere. He's now bought a cheap car to keep him going and takes time pressure off sorting it.

  10. #10
    ⋆⋆ CF Member ⋆⋆ vw rule's Avatar
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    Quote Originally Posted by Dandan62 View Post
    Thanks. Lots of useful info. Going to go down the temp sensor road. Only 2 by dizzy. Think one is fan sensor. One to guage? Also one bolted to top left of engine. Also will check wiring from new lambda now i have some pin numbers. I have stopped him just buying stuff hoping it will fix it. Trying to be more methodical. New dizzy cap, rotor, coil and leads. Pulling each plug lead makes no odds so pretty sure its fueling so ecu getting wrong into from somewhere. He's now bought a cheap car to keep him going and takes time pressure off sorting it.
    Right ok I think sensors in back of head under the distributor, the 2 pin connector one is coolant temperature switch, the small temp sender with the 1 wire is for your temperature gauge.

    Small temp sender in side of head on exhaust side at the top right around the back, (on right side if looking at engine head on) is for oil temperature, again only has the one wire.

    The temperature sensor attached to front of valve cover near cam belt/ air filter area, is the fan over run sensor normally has a yellow stripe around centre of sensor, it monitor's heat still trapped in engine bay once parked up, tells radiator fan to come on every minute or 2 untill heat reduced in engine bay.

    Si
    Had MK2 1.8 Scirocco Scarla 1998 to 2002
    had it lowered on original wheels,
    K&N air fitler and Janspeed exhaust system.

    Now have 94 M reg Corrado 2.0 16v since 2002 still got it, been off the road now since early 2015
    hoping to get it finished this year.

    Also have a 2015 Seat Ibiza TSI i-tech as my daily driver. Plus I'm on The SEAT Forum.

    Link to 16v torque settings & ECU pin locations.
    http://the-corrado.net/showthread.ph...fuel-pressures

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