Engine problems

Discussion in '16-valve' started by joe98, Jan 10, 2019.

  1. joe98 Paid Member Paid Member

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    I’ve recently bought a 1985 Mk2 and I’m having some troubles. The car from the factory came with the 8v engine however it has since had the 16v engine dropped in, its also got KJet injection.

    The problem is that when I’m driving and I go near 4500-5500 rpm or above, the car will stutter and cut out. (The engine will still run but a drone sound comes from the engine when the accelerator is pressed)

    It doesn’t happen all the time and it’s not always at the same rpm but around that area. The cars had a new alternator and battery and it has made it a little better but the problem persists. A local garage thinks it could be due to me having 3 standard plug leads and 1 BMW performance lead (came with the car when purchased). When the engine jerks and cuts out near the rpm range I can hear a relay (or a number of relays) clicking underneath the dashboard. When the engine jerks, it’s possible to slow the engine down, shift down a gear and the car will make it past without jerking all the way to red line.

    It’s hard to explain what’s happening but basically when the revs get near 4/5k the car will suddenly start to jolt instead of accelerating. The car won’t stall out but I have to let off the accelerator for it to stop. This will happen either at WOT or just gradually building up speed.

    What could be causing my problem?

    Any help is greatly appreciated.
     
    Last edited: Jan 10, 2019
  2. pigbladder Forum Addict

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    slightly sounds like hall sender starting to go..does the rev counter go ape?
     
  3. joe98 Paid Member Paid Member

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    I wouldn’t say it goes ape but when the engine begins to jerk, the Rev counter will blip up a bit even though I’m not moving the pedal.

    Any more info needed please ask.
     
  4. joe98 Paid Member Paid Member

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    Caught it on camera. If anyone knows whats up, please get in touch.

    The video clearly shows the car revving up to about 4k then when it gets there it tries to get above 4k but then will drop back down and then try again. You can also hear a relay clicking and the end of the video shows that the engine will rev above 4k. My foot barely moved on the pedal until the last second when it revved up properly.
     
  5. rubjonny

    rubjonny Administrator Admin

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    ok for starters feel all the relays till you find the one which is clicking, let us know which one it is.

    did you use the full 16v wiring, and if so did you change the fuel relay for the 16v one which should be 67, 80 or 167 in slot 2. worth posting a piccy of all your relays as well so we can check they're all good.
     
  6. joe98 Paid Member Paid Member

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    Update:

    I’ve fitted a throttle body screw and it’s partly fixed the problem. The engine doesn’t cut out as harsh as it used to but it’s still annoying.

    What else could be causing this problem? Im assuming the fuel pump is next on the list for me to replace as that could be causing low pressure.

    Thanks for any help guys.
     
  7. rubjonny

    rubjonny Administrator Admin

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    did you figure out/fix the relay clicky problem
     
  8. joe98 Paid Member Paid Member

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    I haven’t looked at the relays yet, that’s tonight’s plan.

    I’m not sure if the 16v loom has been used in the car as I didn’t swap the engine.

    What relay should I be looking out for?
     
  9. rubjonny

    rubjonny Administrator Admin

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    its in slot 2 for CE1 fusebox, slot 12 for CE2 :)
     
  10. joe98 Paid Member Paid Member

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    Finally had time for a proper look at the fuse box.

    So I’m not sure what box this is but the long relay above relay 17 is what’s making the click sound whenever it cuts out and sort of tries to go over 4K rpm.

    With my foot held at a constant rpm the car won’t go above 4k and the long relay will click, the relay is hot to the touch and the metal prongs were very hot.

    I’ve attached some pictures showing this. The relay is definitely the fuel pump relay assuming the German isn’t too hard to translate. The relay is inserted with the text facing up.

    Any help is greatly appreciated.

    Edit:

    The pictures haven’t copied over but I will post them tonight when I’m back on a PC not a phone.
     
  11. joe98 Paid Member Paid Member

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  12. rubjonny

    rubjonny Administrator Admin

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    ok I'd say it has an 8v relay in slot 2, it should be a 67/80/167 though it wont work unless the full 16v wiring loom was used. As long as its not the rev-limiter type the 8v relays will work fine however.

    I guess the 8v loom was left in as you still have the 8v increased idle valve above the fusebox which is the one which is clicking. So first thing unplug the relay, you dont need it. Next go in the engine bay and find the other end and unplug from whatever its connected to.

    without the 16v loom the ISV wont be working either, without that you got to raise the base idle a bit or try an 8v AAV valve in its place
     
  13. joe98 Paid Member Paid Member

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  14. rubjonny

    rubjonny Administrator Admin

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    unplug the relay on top of the fusebox and leave it out. The relay linked is the correct one for a 16v but as I say unless the full 16v loom is used it wont work as the required ecu trigger wire to the fusebox will be missing. Since you still have the 8v increased idle relay fitted it'll still be on the old 8v wiring loom.

    I suspect its plugged into the 16v over-run cut-off valve, if so then it will cause these exact symptoms when the relay triggers :)
     
  15. joe98 Paid Member Paid Member

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    Thanks for your help and time rubjonny but I’m not technically mind so what steps should I take when I’m back at the car?

    If you could use as little jargon as possible it’ll be a great help

    Thanks
     
  16. rubjonny

    rubjonny Administrator Admin

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    1st unplug that relay, you dont need it. see how it runs. if its fine, great, carry on ;)
     
  17. joe98 Paid Member Paid Member

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    Shows how much I know about cars! I’m too scared I’ll blow up my precious gem of a mk2!!

    Sorry for being like this, I’ll give you an update tonight [:D]
     
  18. joe98 Paid Member Paid Member

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    Car doesn’t start at all without the relay, I’ve got a replacement coming tomorrow so I’ll give another update then
     
  19. holdawayt Forum Member

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    Did you unplug the other end of the relay in the engine bay too?
     
  20. joe98 Paid Member Paid Member

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    I may have forgotten to unplug that part :lol:

    Where does the other end unplug
     

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