Approaching 119k mile mark, now I have a bit of a shake at idle.  Not very bad, just annoying.  When I put the air con on it stops.

Any ideas?

What is the purpose of the injector with the wire?  I read on the net this one sometimes goes wrong.

I must say the car has been returning excellent fuel economy, hovering between 45 and 51 mpg on the last continental journey, so there is nothing fundamentally wrong with it, but this slight shake at idle is annoying, as I like things to be like Swiss clockwork.

If it's not running lumpy I'd start looking for tired engine mounts if it were me.

 

Does the V6 have vibration dampers?

 

And as an aside, why is your fuel economy so much better than mine?  :'(

 

Gaz

Remapped that's why. EGR off and optimised other parameters.

The v6 has active dampers.  They activate - energise - when at idle.  They deactivate at higher revs.

The fact it stabilises when climate on - hence 30% more fuel going in at idle - makes me think maybe one of the injectors dribbling at light fuelling levels (5mg/inj at idle).

BTW when speed limits allow and in a hurry 90-100mph cruising returns 40 mpg.

What economy are you getting?

Edited 25 August, 201312 yr by oh_superb

Hi there,

 

I have a 2002 2.5TDI with manual transmission and I am also getting a bit of a shake at idle at times. I had not noticed whether the climate had an effect or not but will see next time it happens. It is not always there. I was thinking that it may be possibly the beginning of DMF beginning to fail. However I would be interesded in your theory about a faulty injector.

 

By the way my fuel economy is very good too getting around the figures you quote but mine is not remapped.

My 20 mile commute is generally open road cruising at 60 to 70mph so maybe ideal driving helps in my case.

Could it be then that one of your active dampers isn't being energetic enough then?

 

Interesting about an injector dribbling - I see where you're coming from.

 

Mine's not mapped and most of my home to work mileage is urban stop-start in traffic.  On a run I can get 44mpg if I'm good.  Current average is as per my sig - 31.6.

 

Did you know, the origin of the word codswallop comes from when the first fizzy drinks were made.  The 'wallop' is the effect of drinking something gaseous out of a bottle invented by James Cod for keeping the fizz in! Funny the odd information we retain 

 

Gaz

The 2.5 engines always end up being a bit shaky as the pump elements and nozzles wear/coke up. The 4 cyl PD engines have dynamic fuel balancing at idle whereby the engine acceleration between firing strokes is measured by the ECU and is used to adjust the fuelling at the next shot. The result is a dead steady idle, even on an engine with starship miles. Contrast that with the horrible Ford/Delphi system whereby the injector flow characteristics have to be programmed to the ECU. It never stays right and has no compensation for wear.

 

The pneumatic mounts needed for the rocky B5.5 engines help a bit - but not much. They fail frequently but unless they're leaking damping fluid, fitting new ones doesn't make a lot of difference. (Put the money into the VP44 piggy bank).

 

rotodiesel.

 

 

Did you know, the origin of the word codswallop comes from when the first fizzy drinks were made.  The 'wallop' is the effect of drinking something gaseous out of a bottle invented by James Cod for keeping the fizz in! Funny the odd information we retain 

 

Gaz

 

Well I was brainstorming to come up with a username and for no good reason I remember a phrase that older generations used where I grew up and "That is a load of codswallop" came to mind. On that basis you should probably take whatever I say as dubious nonsense.  

However I really am getting 45 to 51 mpg outa my Suberb. 

I will not touch anything like the VP44 pump until the problem gets worse but would be interested to see how things develope with other peoples cars

By the way my car is currently at 152k.

 

 

I hate the shake but can live with it.  Hope it's not VP44 trouble TBH! May try some sort of injector cleaner, but may also get it back on a biodiesel diet - it does tend to clean the engine up a bit.  Have not run it on that for a good few months, maybe she's missing it :-)