cylinder problem
 

hi .i have an audi a6 and im having a problem with cylender 4 always blowing plugs. and help would be much appreciated

No codes. When I say blow I mean the plug in cylinder 4 always needs replaced when it starts to misfire badly . But have u ever heard of this? Every time it goes I am driving through a tunnel and every time the car misfired going through it

I doubt it is the tunnel's fault. However, being in the tunnel may allow you to hear a misfire that you otherwise cannot hear.


I would suspect a coil pack problem, especially if you have replaced the plug more than once. Usually the misfire results in an MIL code, too. One way to confirm this is to switch the coil pack on #4 with another coil pack and determine if the misfire follows the coil pack. If it does, you have your answer. If not, then I am not sure what else would cause a misfire on one cylinder if the plug and the coil pack are good.


Keep in mind my experience is with older Audis. If your A6 is newer and has something like direct injection, then maybe you have a fuel injector issue of some sort.

No it defo has something to do with the tunnel . It's not just that it misfires it loses power big time and only when I go through the tunnel . Iv had to replace plugs 4 times on cylinder 4 and iv already changed could packs also. When it happens the car labours you feel it putting trying to pull the car . Then it goes . Plug fails and I have to replace it

Lol Yeh iv started taking the bridge but it adds an extra hour a day onto my journey . It's the Clyde tunnel in glasgow. It's an a6 3.2 fsi sline petrol 05 plate

I'm out of ideas for now. Maybe your A6 is playing games: "A popular game amongst local children, and some adults, is attempting to hold one's breath for the duration of the journey through the Clyde Tunnel. This is possible due to the short length of the tunnel - a car travelling at the 30 miles per hour limit takes 57 seconds to pass through, and at off peak times traffic is often flowing at around 40 mph (a transit duration of 42 seconds). Success is hampered by snarlups (particularly at the interchange on the north end) slowing traffic. The breath-holding game was the subject of Scottish artist http://en.wikipedia.org/wiki/Roderick_Buchanan video Gobstopper, for which he won the Beck's Futures art prize in 2000."

From my research, you are taking either/or " the Kingston Bridge and, much further downstream than the Tunnel, the http://en.wikipedia.org/wiki/Erskine_Bridge."

Lol Yeh u got it . The erskine bridge . Just got a whole new set of plugs from audi and I'm wondering wether to just go ahead and also order new ignition coils and fit them all together .

Do the coil test - switch it to another cylinder and drive that way to check if the misfire moves. This is tried and true way to determine if its a bad coil.

Any oil on the plug? What does the bad plug look like? white tip? black or brown tip? corroded or does it have deposits?

Detonation is definitely not on correct time and the plug is getting a beat-down.