Random high idle fan switching on at low temperatures.

Discussion in 'Maintenance' started by Gilmourr, Jan 15, 2020.

  1. Gilmourr

    Gilmourr Active Member

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    Hi,
    I have a 2006 that developed an issue towards the end of last year. I am getting a random high idle ( rises to 1900rpm from 1400rpm), about 2 seconds later the Fan switches on and stays on till the revs drop again. This can last for 2 seconds or 2 mins, can happen between 70’C and 102’C.
    The Fan still cuts in at 103’C and off at 100’C with no rev rise.
    I have checked out the ECT sensor and wiring all seems good.
    I’ve just checked the valve clearances all are good, plugs all good. I had the issue before checking the clearances.
    Ran out of ideas.
     
  2. Gilmourr

    Gilmourr Active Member

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    I disconnected my PC 3 to see it it was the issue but no joy.
     
  3. Lock

    Lock Active Member

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    Would be interesting to hear thoughts on this as have noticed similar thing on the project 2007. About 60-70oC if rev the bike fan cuts in then goes off, odd! If hold at revs 2-3K fan cuts in until i let it go back to tickover. As you say let temp go up to near 100oC then fan cuts in as normal. My old 2007 didn't do this. Am just changing radiator (as was leaking), fan and flushed all coolant so will see if it still does it
     
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  4. Gilmourr

    Gilmourr Active Member

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    Thanks for the reply. I’ve ordered a second hand ECU and blank paired keys. Going by your reply and other replies on FB pages some bike the fan runs and others it doesn’t. I’m not holding much hope of the ECU sorting it now.
    Seems the fan running is just a result of the high idle. Thinking now more vacuum leak or TPS. It would be good to know what triggers the fan at these low temps. Actual RPM or throttle position
     
  5. Gilmourr

    Gilmourr Active Member

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    Sourced a replacement ECU, was like waiting on a bus, couldn’t find one then ended up with 2,. One returned after giving up hope of getting it due to postage error by the seller. Need to try and return the other as it made no difference, but it’s return policy is not so clear.
    Seems like if the revs sit close to 2k the fan will run. The real issue is the idle surging up to 2k for random amounts of time.
    When moving the manual idle adjustment, it can be set at 1400 but jumps to 2k with next to no adjustment. No progressive change. if the idle is set lower the bikes idle is rough and sounds nasty.
    I’m now thinking throttle bodies.
     
  6. Lock

    Lock Active Member

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    Don't get the rough idle with mine, just fan cutting in if revs held at ~2000rpm when temp is around 65oC. If left at idle fan kicks in normally at around 100oC. Odd! Changed rad and coolant at weekend and no different (rad needed changing). Have a fan off a 2005 model - doesn't fit the 2007 rad but could try hooking it up and seeing if it does the same thing
     
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  7. Gilmourr

    Gilmourr Active Member

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    Cheers for the reply.
    Going by the response on various pages and forums the fan coming on seems normal. My issue is the randomly rising and falling rough idle. Once up at temp the #1 and #2 headers are approx 90’C higher than #3 and #4. I pulled the plugs and 3 and 4 look rich.
    Vacuum lines and TB mounts look ok. No rise in revs when carb cleaner sprayed around that area.
    Need to buy some tooling then try a TB sync.
    Bike pulls great and smooth, only have an issue at idle.
     
  8. Gilmourr

    Gilmourr Active Member

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    Was the Rad a perfect fit? I fitted a Chinese Rad and it’s around 15mm shorter and slightly wider.
    Do you have a link to your Rad?

    I’m now replacing the Throttle body rubbers to try and cure the rough idle.
     
  9. Lock

    Lock Active Member

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    Ordered this one off of ebay, got for £95 delivered - https://www.ebay.co.uk/itm/OEM-Repl...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

    Doesn't fit perfectly, as you say shorter so had to fashion an extra part to the bottom bracket - but doesn't matter as have a rad guard covering so can't see the rad itself. Also pipe to top hose is at slightly the wrong angle, bent it up a little but didn't want to snap it! Top hose is a little tighter than i'd like but its ok for now.

    Do like the look of the aluminium ones, not that much more expensive. Might get one of these if i need another.
     
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  10. Gilmourr

    Gilmourr Active Member

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    Sounds exactly the same as the one I fitted.also had to add a small bracket at the bottom. I tie-wrapped the original guard back in place. Small gap at the bottom and the RH upper fairing is a stretch around the bottle. I’d pay another £100 ish if I could find a perfect fit.
    New throttle body rubbers going on once I’m off work. Hopefully sort out the rough idle.
     

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