A3 Cylinder 2 misfire

[bannonn]

My A3 1.6 fsi 53 reg decided the other day to play up. Was driving along when it started to blow out bluey coloured smoke as if I was burning oil. In 2nd gear around 2000rpm and climbing, if started to splutter as if it was over fuelling untill I literally put the pedal to the floor, it the also done the same in 3rd gear. Took it to my mechanic who done a diagnostic on it using his VAGcom reader and it had cylinder 2 misfire code P0302 - sporadic misfiring. Oh and another fault that my system was running too rich.

I've replaced all 4 spark plugs, checked and swapped injectors over and checked and swapped over ht leads with my mechanic for the process of elimination and changed the coil pack, yet it still does it. When I first changed the spark plugs over, it worked fine for about a day and then went back to it's spluttering and eventually misfiring again only on cylinder 2. My car now seems to work fine only when I clean cylinder 2 spark plug and put it back in, after about 5 miles it repeats the same problem? I'm baffled and so is my mechanic on what the problem is? Every time I take the spark plug out, it is covered in black soot/oil when I know it should be a greyish colour.

Anyone know how to sort this problem? Would be much appreciated!!

[bannonn]

Anyone? Also done a compression test and that seems to be fine aswell

[Tech]

Hi Bannonn, have you noticed if the car is using any oil?  Also, is the car defiantly a 1.6 FSI, not an MPI?  The 1.6 FSI was very rare in the A3 (common in the Golf) and it did not have HT leads, it had coil-on-plug.

 

Tech

[bannonn]

Yeah it's definately an FSI, it does have a coil pack, it has one, which the leads connect too? (This could be the coil plug leads?) and yes it is burning oil.

[Tech]

Hmm, the FSI has one coil per cylinder between the two camshafts and I have only ever seen one (imported) A3 with that engine, it was more common in the A2, you have the MPI engine if you have the single coil and plug lead set up.

Any way, If the engine is burning oil, it sounds like this is what is causing the spark plug to become fouled on cylinder 2, therefore you can rule out the ignition and injection components. You need to have a cylinder leakage test carried out and possibly e cylinder head removed to check for leakage on the valve stem seals or piston rings.

Tech

[bannonn]

Would the compression not be affected by a leakage in the valves or piston rings like you say? Because I've done a compression test and that's fine? (Sorry, I'm a newbie to all this type of stuff aha)

Thanks

[Tech]

If the leakage was really bad then yes, your right, it would show up on a compression test.  However, a compression test only shows that the compression is ok on that one compression stroke (which happens very quickly, even when only turned over on the starter motor) therefore, a compression test is a good way of checking for major engine damage, but not much else.  A small leak will not show up.

 

A cylinder leakage test on the other hand will allow you to see if excessive air is leaking past the valves or stem seals of individual cylinders (with the rocker cover removed and the piston tested at TDC).  This can help you spot problems before committing to the expense of removing the cylinder head.

 

You could have oil leaking into the cylinder on a night and fouling the spark plug when you start the car the next day, too small for a compression check to show.

 

Tech 

[bannonn]

I will do a cylinder leakage test tomorrow and post the results on here. I'll be willing to change the valves but will do the test first for the reason like you say, don't want to be paying out if it's not the problem haha.

Thanks for your input so far! Will definately keep you posted tomorrow!

Jordan

[NELU_BURZO]

Hello Bannonn,

I have the same problem as you, please tell me if you solved it and if so, how ?

Thanks,

 

[Magnet]

Hello Burzo, 

Welcome and thanks for joining. 
I think it’s highly unlikely that the original posters will respond 10 years on, but we never know. 
I have removed your E-mail address from this open forum for your own security, and anyone can contact you via. a forum PM as necessary. 
Would you be able to outline what the exact issue is and what you have done so far to try to solve it.

Kind regards,

Gareth.