Diesel Idle Judder

Technical questions and answers about the Mazda Bongo

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Rich2140
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Diesel Idle Judder

Post by Rich2140 » Wed Jul 22, 2015 10:53 pm

Hello,

I've just bought a 99 2.5 Diesel Bongo with 80,000 on the clock. I'm really happy with it but there is a slight issue with juddering at standstill.
It only judders when stationary and at idle, it is idling between 700-800 rpm but is a bit jumpy between 500 and 1000.
Strangely when I turn the air con on the idle drops instantly down below 500?? and the juddering gets worse.

Any ideas on a fix?, I have read about the idle adjustment but am confused as to why it is inconsistent and why the air con affects it.

Cheers

Rich
BigPanzer
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Re: Diesel Idle Judder

Post by BigPanzer » Wed Jul 22, 2015 11:52 pm

Hi Rich,
I don't know that much about oil burners, but the first thing I would suspect is the glowplugs and/or the 12v supply to the glowplug rail.

Re: the aircon, the compressor needs engine power to drive it. Increased engine load at tickover = a drop in speed and this would be particularly noticable with a duff plug.

No doubt somebody with a bit more knowledge will be along shortly to confirm this or tear me to shreds!

Cheers
Peter
Bob
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Re: Diesel Idle Judder

Post by Bob » Thu Jul 23, 2015 12:04 am

These old diesels do judder a bit, and turning on the aircon increases the load on the engine, most noticeable at idle.

If you tell us roughly where you are someone may have a listen or let you compare theirs.

And welcome aboard, Rich. :D
Take a torch, toilet roll, and tea bags.

https://m.youtube.com/watch?v=hcF9JSxkUSE
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sotal
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Re: Diesel Idle Judder

Post by sotal » Thu Jul 23, 2015 12:41 am

Does it do it all the time or just when you have first started up?

Ours sometimes judders a little when first started from cold, a little blip of the throttle settles it down though.

Idling in traffic it always seems very smooth - with or without aircon on. You can hear the engine note change with aircon on though.

Ours is a 1999 2.5 TD too. Ours just had a full service if that makes a difference :)
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cmm303
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Re: Diesel Idle Judder

Post by cmm303 » Thu Jul 23, 2015 7:41 am

sotal wrote:Does it do it all the time or just when you have first started up?
key question!

If the judder is something that can be heard then it might be worth posting a link to a video.
Chris with BertieB
'96 White unconverted AFT 2.5L Diesel 4WD
wonkanoby
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Re: Diesel Idle Judder

Post by wonkanoby » Thu Jul 23, 2015 8:03 am

http://www.igmaynard.co.uk/bongo/forum/ ... n+actuator

2 little sucky bits in this thread

1 causes throttle to advance from a cold start

2 other bumps up idle when a/c kicks in
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Northern Bongolow
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Re: Diesel Idle Judder

Post by Northern Bongolow » Thu Jul 23, 2015 8:21 pm

cold start solenoid fault. the one with the white plug isnt working or the pipe is off.

have a read of this mate.

http://www.igmaynard.co.uk/bongo/forum/ ... ds&start=0
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