Rough idle...

[lcfc-uk]

Hi all,
I have recently noticed a rough idle when stationary, I have searched and searched for a cure but nobody seems to have one, someone has suggested that it maybe coil overs and others have suggested that it could be vacuum hoses.
Could anyone suggest what sizes hoses I would need I'm thinking a couple of meters of 4mm internal size but I don't want to order the wrong size, can anyone confirm sizes please,
Car is a 2006 a4 avant b7 s line,
Many thanks.

 

[DrEvil]

I would start with changing houses at random. Start with reading error codes, maybe doing some logging and take it from there, or take it to a decent indy garage for diagnostics.

 

[joinerman]

Who ever suggested Coil overs is pulling your chain.

 

[ajax1976]

Rough as in the engines missing or stuttering, revs jumping etc or rough as in you're actually feeling it in the car, vibration etc?

 

[DrEvil]

Who ever suggested Coil overs is pulling your chain.

I was guessing that he meant coil packs? Otherwise that is definitely a garage to stay away from!

 

[joinerman]

I know

 

[lcfc-uk]

Yes sorry coil packs!!!! Duh...
Rough as in vibration, shaking.
The engine isn't missing or stuttering.

 

[francie]

I've the same problem. People have suggested
Dual mass flywheel
Egr valve
Engine timing out
Engine/gearbox mount worn
Crankcase breather blocked.
I haven't followed up on any of them. Bugged me at the start but I've sort of got used to it.

 

[ajax1976]

Yes sorry coil packs!!!! Duh...
Rough as in vibration, shaking.
The engine isn't missing or stuttering.

I'd be thinking engine mounts to start with. Check the side ones for signs of leaking fluid and if possible scan the car, they should throw a code if they're faulty. Its possible that the valve has stuck closed in them so they're not opening at low revs to soften the mount at idle revs. Or it could just be the snub mount, a scan won't see it but you can get a good look at it yourself with the under tray off, cheap and simple diy fix.
I'd definitely try and get it scanned first and have a good look at the mounts before replacing anything.

 

[Cliffy]

this could be the mounts as my car does the same at idle, my engine light is on and the fault code says 'left engine mount solinoid upper limit reached' I havnt investigated the problem further so I'm not sure what this means,

I would recommend getting it plugged in and checking for fault codes then you know exactly where to start looking

 

[SDHA4SLine]

If it's the same as my 2006 tdi and if I remember correctly for some strange reason only the n/s mount has a solenoid/electrical connection so you may need to manually check o/s as the vcds won't pick up a fault on that one.

If you do need new mounts they only seem to be available through Audi dealer or tps unless you go aftermarket upgraded (stiffer) mounts. If you get a quote for genuine mounts make sure you're sitting down!

Edit,

If it does turn out to be mounts this is my post showing prices.

http://www.audi-sport.net/xf/threads/engine-mount-prices-making-me-cry.230488/

After reading through it to jog my memory I have to correct my statement above as it turns out our cars can have sensors on both, just one or neither mounts

 

[lcfc-uk]

Cheers for the replies, had the car scanned this morning and surprisingly no faults codes showing up.
The vibration (shaking) is getting a bit worse, I was sitting outside the shops earlier with a coffee in the cup holder and I could see the ripples in the coffee, Grrrrrr.

 

[DrEvil]

Some logging whilst driving could help, e.g. misfires whilst driving, fueling etc.also what are the long term fuel trims reading ?