Strange Idle 2.5lt

Strange Idle 2.5lt

Postby asha31 on Thu Oct 06, 2016 7:14 am

Hi there; I have a 2010 MN with 165,000k on it its developed a strange noise at idle when warm, almost sounds like the AC is on and the revs change slightly, then after maybe 30 seconds it does a little surge and goes back to normal, you can blip the throttle and it goes right away, all servicing is up to date, filters etc. Reminds me of another Diesel I had with a DPF when it use to go into Re-gen mode. The EGR has been turned off long ago. thinking it might be injector related?? any ideas?
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Re: Strange Idle 2.5lt

Postby OffRoadDave on Thu Oct 06, 2016 8:21 am

Mine has done this twice to me, and only once has it lasted long enough for me to get near the source of the noise once, I think it's probably a sticky suction control valve, but since it's not repeatable on mine I haven't been able to do any further investigation.
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Re: Strange Idle 2.5lt

Postby aids84 on Thu Oct 06, 2016 6:34 pm

Once warm and left to idle they will do their own SQL (small quantity injection learn), which is what you're hearing. Sort of like a more tinny noise from the injectors is the best way I can describe it, same noise happens when you do a forced SQL with the MUT3. The MUT3 SQL is more comprehensive as it varies the revs and relearns over a wider operating range.
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Re: Strange Idle 2.5lt

Postby Crash486 on Fri Oct 07, 2016 6:01 am

Thanks for the info aids84, mines been doing it for years, good to know what it really is!
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Re: Strange Idle 2.5lt

Postby NowForThe5th on Fri Oct 07, 2016 6:51 am

aids84 wrote:Once warm and left to idle they will do their own SQL (small quantity injection learn),


Ya learn something new every day in this joint. ;) Awesome. 8-)
Chris

If work is so terrific, why do they have to pay us to do it?
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Re: Strange Idle 2.5lt

Postby asha31 on Fri Oct 07, 2016 10:41 am

Thanks for confirming that makes sense! i was about to trade her in... :D .. Nah just kidding.
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Re: Strange Idle 2.5lt

Postby asha31 on Fri Oct 07, 2016 10:53 am

On the injectors I have noticed it has got a lot louder on cold mornings these days. Are people changing over there injectors as preventative maintenance or when they die? Done 165K.
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Re: Strange Idle 2.5lt

Postby snowman on Fri Oct 07, 2016 11:09 am

asha31 wrote:On the injectors I have noticed it has got a lot louder on cold mornings these days. Are people changing over there injectors as preventative maintenance or when they die? Done 165K.


I have just done mine at 160k.

There is strong evidence developing that injectors can be the main cause of engine failure in these things and hence why i did mine.
This car is like a bad drug habit. It is taking all my money and time, my family are concerned, but new mods just feel sooooooo good.
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