Just curious if anyone would know why my car will sometimes hesitate when pressing the gas and then make a loud popping noise? After the noise, acceleration is normal. I would appreciate any info you could give.

2001 A6 2.8 Q

Hi,

I've had this happening to me for a while and I've actually found that the housing for the air filter had blown off and hit the underside of the bonnet.

This has been happening to me on random occassions and i tried to explain this to my brother who is a mechanic but it would never manifest itself whenever i tried to show him. Then one day at his home, it did it and then he believed me.

He had my A6 2.8 quattro at his garage and when he hooked it up to an emissions tester, both pipes were reading 11.5 where they should be about 0.5. So he popped the bonnet and as he did so, both readings went down to 0.3 - where they should be. he has found , that intermittedly there seeems to be a build-up of pressure and that a load of fuel is being pumped in which is causing a backfire now and again. He has since discovered that there is solenoid (can't remember which one exactly) which activates something to do with the fuel tank pressure and because my solenoid is a bit dodgy, I'm geting this massive pop now and again.

He says that a new solenoid would be about £55 but for the time being what he has done is that he's loosened the filler cap because he said that he noticed that when he undid it (and obviously released the pressure) when the engine was running, the engine noise changed and it hasn't popped since.

If this is the problem, then I will obviously buy a new solenoid, but he' giving me the car back so that I can drive it for a week or so to see if it still pops or not. He says i know best about the car so he's letting me test it first to ensure we've isolated the problen before purchasing the new solenoid just in case it's something else that's causing it.

lui