High idle in N and P - 2.5D

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EdRobson
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High idle in N and P - 2.5D

Post by EdRobson » Sat May 25, 2019 9:01 am

Hi all

My 2.5 diesel is idling high in N and P, usually idles around 1k, but is revving up to 2k sometimes. Seems to happen more on short runs, but it's not exclusive. Any ideas?
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mikeonb4c
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Re: High idle in N and P - 2.5D

Post by mikeonb4c » Sat May 25, 2019 9:09 am

EdRobson wrote: Sat May 25, 2019 9:01 am Hi all

My 2.5 diesel is idling high in N and P, usually idles around 1k, but is revving up to 2k sometimes. Seems to happen more on short runs, but it's not exclusive. Any ideas?
Think it should idle nearer 800rpm anyway? Has this come on suddenly. When engine cold or hot or both? Have filters all been changed recently? Any sign of leaking from diesel pump? Is it starting normally from both cold and hot? Has any work been done on the engine recently? Is it changing gear normally? Anything else started behaving strangely that you can think of? The answer to questions like this might help diagnosis etc.
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EdRobson
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Re: High idle in N and P - 2.5D

Post by EdRobson » Sun May 26, 2019 8:42 am

You're right, it is idling at 800 normally, running up to 1600ish. Usually when it's not been running more than 1/2 hour. No work done recently, serviced late 2017 and has done 3-4k since then. Gear changes are fine. I think I'll sort my filters anyway, just to see what happens.
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Northern Bongolow
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Re: High idle in N and P - 2.5D

Post by Northern Bongolow » Mon May 27, 2019 11:14 am

I would look round the pipework to the cold start solenoids. If the main vac pipe sucks flat with vac from the pump this can hold on the cold start system, the standard pipe is a thick walled one to avoid this but if it's been replaced with a substandard pipe it can suck flat when the engine gets warm. Try temp removing the Lecky feeds to the solenoids, this may indicate if they are holding on causing revs to rise.
Check throttle cable adjustment also make sure the cable end is hitting the plunger at the end of the stroke etc.