It’s a 2004 reg with 70,000 miles on the clock has been running fine since my Mum bought it and ran faultless the 152 miles to Abersoch and half way back were she made a fuel stop. It has since become hesitant under normal acceleration from the lights. It’s kind of judders like going over a rough road. If you acclerate hard it doesn’t seem to do it as much.

No warning lights are displayed on the dashboard and it doesn’t do it all the time.

It’s a automatic. The car had been stood for three months at the dealership prior to her buying it. It’s a 2.4 V6 engine. Seems to idle well enough but quite a high idle speed.

Any ideas?

Something in the fuel? Refilled it yet?

She emptied the tank nearly on the way to and half way back from Wales and then filled up. But not sure how long the fuel in the tank when it had been stood for a while. I know when my motorbike stood for two months it ran like garbage on the fuel left in the tank.

I was meaning the new fuel that was put in, if the tank was taken to nearly empty then filled there might be something in there too.

Plan then just run it down to quarter tank and refill?

From your description of events it does point towards crap fuel. Run that fuel down most of the way (not to fumes though) and refill. See if it still does it with some decent fuel from a proper branded petrol station. Avoid supermarket stuff, just this once at least. Give it a few miles to reset itself.

If she ran it right to the bottom of the tank it may have sucked in some of the sedimentary crap at the bottom. Or she may have bought some dodgy petrol. Bad fuel might not automatically mean dirty fuel, in my limited understanding as fuel goes off it’s octane rating drops so she could try filling up with 99ron super unleaded and adding an octane booster to bring up the octane rating of the fuel in the system. Millers is supposed to be the best.

She bought an A4 Cabriolet? And drove it to Abersoch?

*stifled giggles*

Her last one did this when she put Morrison’s fuel in. Try some Shell v power in it see how she gets on.

If I understand correctly, its a new purchase?

I’d run it on some premium as above, and then back to the dealers. If it ran OK on the better stuff ask them to change the fuel filter and prefilter if fitted, if it still shudders ask them to diagnose and fix.

If you are happy and you ask for the filters to be done, at least you’ve got a record of the incident and the dealer knows which puts you in a better position if it turns into a bigger issue. You don’t know if its been traded in after the previous owner filled it with diesel or some other misshap.

Or a coil pack on its way out.

Had a petrol A4 that did this, it was the MAF sensor.

See if you can clean the sensor first.

On my old 1.9TDI (of course different VAG engine)- the sensor was ontop of the pipping and was easy to unscrew, unplug and spray with electrical contact cleaner. This sorted out rough running.

Fuel filter a bit blocked?

If it was a coil pack you’d know it, I used to carry a spare in my Seat. They went from fine to f***** in 60 seconds rather than dying slowly IME.

Been sitting a while ?
Could be coil packs (check for the Free Recall by Audi, the new ones are Grey the old ones are Black)
MAF sensor, It’s a pile of poo and like most Audis the sensors fail long before anything else, try that, get someone to check the Fault Codes………. … … …… … …… … …. ……..
Fuel Filter’s a distinct possibility..
Put some Shloooper Unleaded in it and take it for a Blast…
Also, it maybe the sensor in the radiator which shows the coolant Temp, this fails too as it’s in a stupid place.
And check around the Coil Packs for moisture.. Theres a tendency for damp to cling to the bonnet then drip right on the coil packs and create a short.. It happens so see if theres any moisture down there..
And, not wanting to scare you.. the cam gasket fails spurting oil onto the coil packs too..

Don’t go spring WD40 everywhere… Because thats just silly.

PePPeR – Member
Or a coil pack on its way out.

Wondered about that initially but it didn’t sound like the symptoms when my coil packs went. It wouldn’t run right at all when they went. Not intermittent – all the time. Awful fuel consumption and performance too!

I’d be looking at the fuel side of things.

By the way, thanks again Bikebouy for the heads up on the product enhancement on coil packs. Not sure if you got my thank you the first time round. Mine have been fine since they were done.

Good luck OP with sorting it. Lovely cars. Mine’s just turned 100k on a 54 plate and still feels great and goes well. Hope your mum’s does too!

As has been said, sounds like coil packs. Ring your local dealer with reg/vin number and they’ll be able to confirm if its been done yet under the recall.

JulianA – Member

By the way, thanks again Bikebouy for the heads up on the product enhancement on coil packs. Not sure if you got my thank you the first time round. Mine have been fine since they were done.

I hadn’t but hey, if I can help I will, Cheers 😀