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Surging Revs / Hunting

Discussion in 'Land Rover Freelander' started by freelander1xdi, Jul 11, 2014.

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  1. freelander1xdi

    freelander1xdi Member

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    freelander 1 lseries

    last year i was having issues with surging revs, it seems to do it particularly when its hot, it goes after a few blips sometimes but other times it doesnt just sits around 1100, then can drop down to just over 500 which is where it seems to idle usually when its at 1100 it seems lumpy weird and slow to respond to blipping the throttle

    First I took the maf off cleaned it and it seemed better and then i just disconnected it all together which has fixed it for over a year but now its back.

    Had it in the garage and they said it might be a loose pipe and air getting in somewhere or a break in a pipe but cant find anything.

    apart from this it runs really well plenty of power no issues at speed or anything. Someone else mentioned a crank position sensor, I had a similar thing on my BMW diesel and it ending up being the loom had burnt out.

    any ideas anyone?
     
  2. GrumpyGel

    GrumpyGel Well-Known Member Full Member

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    If its revving high (not revving low or cutting out) - my money's on the switch that's on the accelerator.

    As revs are fly by wire, not a throttle cable.

    Would a Hawkeye show what the ECU thinks the accelerator is as?
     
    Last edited: Jul 11, 2014
  3. Danielsand

    Danielsand New Member

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    I would start with smoke test first, to find the possible vacuum leak. If that's OK, gas pedal switch, throttle position switch, and ECM. In that order.
     
  4. freelander1xdi

    freelander1xdi Member

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    thanks alot guys

    How do I do a smoke test.
     
  5. Danielsand

    Danielsand New Member

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    If you look on Youtube, some people do it while smoking the cigar! There IS a "smoke machine" that some garages have (I think it's easier to use than the cigar, considering the fans, and the airflow generated by the belts and pulleys).

    Basically,.....you "blow smoke" all over the vacuum hoses, and see where it's been sucked in! Simple, but effective in finding the vacuum leak.
     
    Last edited: Jul 11, 2014
  6. htr

    htr Well-Known Member

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    Cigar! but which one? Presidenté, parejo, panatella, or a nice cheroot? : D:5bsifone:
     
  7. Danielsand

    Danielsand New Member

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    The CHEAP one of course! I smoke "Monte Christo", and since I live over here (and "our" government hating Cuban), I pay dearly to get them from Canada. Politics at your finest. Makes me sick.
     
  8. freelander1xdi

    freelander1xdi Member

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    On YouTube they seem to push smoke into the hoses to look for it espaping seems a bit complicated, I'm going to remove each pipe and give them a clean and check for any breaks.
     
  9. Danielsand

    Danielsand New Member

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    I didn't see that one! Basically,...the smoke machine "fogs" up the whole engine bay, and IF there is a vacuum leak, the smoke will be sucked into the system, and easily seen. It could be dried out hose (at the clamp), loose clamp, pinhole in the hose, or a split.
     
  10. freelander1xdi

    freelander1xdi Member

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    cool will give it a go thanks for the advice
     
  11. freelander1xdi

    freelander1xdi Member

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    Update on this

    I have run a smoke machine over the pipes and cant see anything running into any pipes that would suggest theres a leak that is sucking air into any pipes assuming that's correct as in what could cause this issue

    I have also inspected all the pipes tightened them all up they look fine

    When i was running it earlier it started hunting and surging so i left it and tried to put the smoke on it again and nothing cant see anything. So im ruling out that? What do you think?

    I have been searching on the forum and someone mentioned that they had a similar running lumpy surging, and had unplugged the temperature switch to put the fans on constant and it fixed it, i might add mine only does this when sat in traffic. So I have run it up to temperature and kept the throttle at 2.500 revs to get it hot it then started surging and hunting again i got out of the car and unplugged the temperature switch and after 20 seconds or so it went back down to normal tickover and wasnt surging or hunting.

    Obviously the fix is not to leave off my temperature plug but what is

    is this as simple as I need a new temperature plug? will that make the fan come on when the engine is getting hot

    I am not using losing any water, the engine runs really clean an initial small amount of smoke on startup and then you cants see anything out of the exhaust and this thing only happens when the engine is sat in traffic and hot.

    Also my engine temp never goes over 9oclock in the middle ever and never has even in traffic when its running lumpy surging

    Also thanks alot for all your replies helping me out its much appreciated
     
    Last edited: Jul 13, 2014
  12. GrumpyGel

    GrumpyGel Well-Known Member Full Member

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    I've never seen the temp gauge go over 1/2 way in my L Series. I don't get to test it in UK type traffic situations, but it has pulled boat and camping gear over some pretty serious mountains.

    It gets to 1/2 way and stays there.
     
  13. freelander1xdi

    freelander1xdi Member

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    mine doesnt either however in traffic it runs lumpy when hot and surges

    But if I take put the fans on constant it runs fine

    I am trying to find out if the temperature sensor or wiring from it is not kicking in the fans.
     
  14. ZDomZ

    ZDomZ New Member

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    If unplugging the temp sender works I would give a new one a try.... I wouldn't expect it to be a lot of money.
     
  15. Danielsand

    Danielsand New Member

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    I don't think temp sensor has anything to do with it. I'll give you MY opinion, and remember, I am a half a world away, with no possibility to put my hands on your car, and check for myself. I am going on only what I read in your post (symptoms).

    At least the smoke machine verified that all vacuum is good. Time well spent.

    I think leaving the fans on, cools down the engine bay just enough to cool off throttle position sensor. They DO fail with heat, and that's why the new ones come with the heat blocking grease that you smudge on the back of them. I "salvaged" some (at the stage you describe) by taking them off, cleaning them, and replacing the grease on the back of it.

    I lived in Arizona for about 10 years, and these things failed often in the desert heat.
     
  16. freelander1xdi

    freelander1xdi Member

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    Hey guys its a Fix on this surging high revving problem. The coolant sensor has been replaced and its fixed ticking over at just over 500 never moves now, feel loads better its not fighting itself to tickover and is alot more responsive.

    Might I also ad the computer at the garage picked it up straight away the sensor was reading -35 on a hot engine so obviously it was making it do weird stuff to the fuel. So if you have this issue of surging hunting revs and over revving on a l series try the coolant sensor. £6 hope this helps someone else.
     
  17. Stuart hall

    Stuart hall Active Member

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    An old thread but may get some response,
    My old girl is running very well but noticed yesterday on drive home a slight hunting/ surging if that's the correct term when stationary.
    The revs rise and fall by about 100 rpm in a regular pulse every second or so.
    Is this something to worry about ?
    What could I do to check it myself ?
    Apart from that engines running the best in ages, no smoke ever and pulls well etc.
    Thanks guy's.
    Oh and I recon she's doing around 35 mph
    Put fuel in yesterday, 82 p per litre ( sorry guys lol )
     
  18. GrumpyGel

    GrumpyGel Well-Known Member Full Member

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    This is a common misconception with the Freelander L Series.

    The engine is actually running very smoothly, it is just your surging heart rate and adrenalin rush making your senses hyper sensitive making it appear as if the engine is surging. Quite normal when driving such a finely tuned sporting beast of a vehicle.

    If you're on beta-blockers and the engine is actually surging, I'm not sure what is at fault.
    Diesel price here in Canterbury is currently $1.34/L, its expensive down here compared to Auckland where its generally $0.05-$0.10 cheaper. According to xe.com, $1.34 is £0.695.

    You can almost always get up to $0.10 off per liter by "swiping" your AA card and often get up to $0.40 off with discount vouchers from supermarkets.

    This includes GST (VAT), however, there is no fuel tax on diesel and diesel cars need to pay for RUCs (Road User Charges) which are currently $62 per 1,000 kms (up to 3.5 tonnes). At 35mpg, that's $62 per 80 liters - or $0.775 per liter - knocking the fuel price up to $2.115 (£1.097) before discounts. Of course, in the "good old days", people used to just disconnect the speedo - its more complicated these days with cars running on computers!

    You have to display an RUC paid card on your windscreen showing the mileage you've paid up to for plod to check, eg...

    RUCCard.jpg
     
  19. Stuart hall

    Stuart hall Active Member

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    Lol doubt it's my heart rate Gerald !
    Mind you I nearly needed some new undercrackers and a seat cover when a tourist pulled out in front of me ( couldn't throw the anchor out in time )
    Think your regs are very complicated, but think we're the lucky ones, last time I looked derv was £123 ish per litre back in UK !
    Probably more now.
     
  20. Stuart hall

    Stuart hall Active Member

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    See how much I take notice, thought you had an expensive lander not a disco or are you one of those polluting two car families ?
    You could tell them it's only 2wd now and so kinder to the sheep !
    Surely if they just taxed the fuel, those who do more miles would pay more or would that put too many pen pushers out of work ?
     
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