I had my Edition 30 remapped recently and was finding that right at the top end of the rev range (6500+ RPM), it would misfire and always on Cylinder 3. Plugs + Coilpacks were then changed, but this didn't help.
Spoke to Nick at R-Tech and he mentioned that I should google "valve float" or "valve bounce". Doing so revealed what is commonly known as the "weak valve springs" issue on many Audi S3 & TTRS/VW Pirelli/Ed30/Seat Cupra roughly during 2007-2009. Just great
. Fortunately there was a UK Audi TSB issued which basically described the issue that affected some standard cars and the bad springs were marked with 3 stripes: 2 yellow, 1 white, or 3 yellow-ish stripes.
So I pulled my valve cover and found this:
Definite confirmation that my Ed30 (very late 2007) had the dodgy valve springs fitted from factory. The issue is normally made worse as a result of higher exhaust back pressure and the weak spring not being able to close the valve. This is only an issue on the exhaust side and technically the inlets probably don't need changing.
The correct springs are meant to have a single yellow and blue stripe, like the ones I bought here:
More research would indicate that this is usually a head-off job. However, tools do exist to allow you to do this in situ, but I couldn't find any confirmation that this would work on the FSI engine. This post is basically to show it CAN be done! I bought the tool and took it to my friend (who incidentally is a *very* good mechanic) and we decided to give it a go.
First, valve cover off and timing chain cover needs to come off:
Timing chain revealed:
Then, timing belt cover off so we can mark up timing. Getting the side engine mount out was probably the hardest part of the job
Next, camshafts out. We couldn't get the exhaust pulley off, so just placed it carefully to one side. After that, we installed the tool (
http://www.amazon.co.uk/Laser-5258-Valve-Spring-Compressor/dp/B006IRIPD8):
The springs are then compressed and collets can be removed, and then the retainer. The spring can then be removed. Note that when doing this, compressed air must be fed into the spark plug hole of the cylinder that you're working on. This is to ensure the valve doesn't fall down the cylinder - it is also good practice to make sure that cylinder is at TDC too.
First spring out! Look at the difference between the two, just like the Audi TSB documented. Bad on one the left, correct one on the right:
16 springs later, and all back together... well almost!
In total, the job took 8-10 hours in total, bearing in mind this was the first time my friend has worked on an FSI engine. He's primarily a Volvo/Focus ST specialist. It's a fiddly job and one I would suggest getting someone very experienced to do. Huge thanks to Tim
The real test would be repeated pulls to the redline. Normally, it'd misfire anywhere after 6000+ RPM, normally closer to 6500. 20 or so hard pulls later, some to 7200 RPM (I don't think it got that far before because of the misfire) and glad to report absolutely no misfires! Problem sorted in my books
Just to re-iterate, this is a common problem and usually will occur on remapped cars, so is well worth doing. Some tuners are able to tweak the map such that the power is reduced towards the top end, however, I wasn't 100% comfortable with this as it'd always be in the back of my mind that the car has the weaker springs. Parts come to about £200.
If anyone wants this doing, I couldn't recommend Tim more. He's based near Leicester and now has the tool to do this ;)
