Rough idle audi a3 2.0 tri 2010

[Darylbob]

Morning folks just wondering if anyone can point me in the right direction of where to start with a rough idle🤔, injectors? Everythings fine apart from idle power deliverys fine, funny thing is it seems to get rougher when it gets up to temp

[cliffcoggin]

Morning Daryl. It's going to be sheer guesswork unless you tell us some details of the engine. Size, fuel, transmission, condition, mileage, service history, anything that might some context to the problem.

[Darylbob]

Hi cliff sorry I should've thought, so the car is a 2.0 tdi 170 with 100k , it's got full service history, bought the car a few months ago just replaced the clutch and dmf, the oil an fuel filter have also been done. 

[Darylbob]

The car seems in fairly good condition 

[cliffcoggin]

That narrows the field a bit Daryl. While it could be the injectors they are generally reliable and durable so it is worth looking elsewhere initially. Things to look for include: an air leak into the manifold, a faulty mass flow meter, and any hose, pipe, or connector that might have been disturbed or dislodged during the clutch change.

[Darylbob]

That's great cliff thankyou, the rough idle was their before the clutch change so another thing off the list👍, it wont be till the weekend till I get a time to have a go at it, dont know why I didnt think of the maf, I've just sold a can of maf sensor cleaner on eBay I used on my last car🤦‍♂️. As regards to air leak into the manifold how would I go about that? Something I've not done before.

[cliffcoggin]

An inward air leak is going to be a swine to find, unlike an outward leak where you can spray soapy water and look for bubbles. If you are lucky you may be able to hear it; otherwise it's a case of look and feel, particularly any sort of flexible connection.

[Magnet]

Hello Daryl and Cliff,

I know you are not a fan of WD40 Cliff, but it could be used to advantage in establishing if the inlet manifold joint is letting air in, by spraying around the gasket while holding the revs at around 1500 to 2000rpm. If this gasket is leaking then you are likely to see the exhaust smoke becoming blue in colour as the WD40 gets sucked in and burnt. 

Kind regards,

Gareth. 

[cliffcoggin]

Gareth, my only objection to WD40 is when it is used as a lubricant. If it will find a leak in the way you describe I am happy to endorse it. Spray to your hearts content Daryl. You could have the sweetest smelling exhaust in the world.