Another S3 misfire


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Aug 7, 2020
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Had car 4 years, 09 CDL , 44k miles, serviced up to date.
Cruising around 50- 60 mph Eml flashes and will turn solid after around 20 miles , codes are P0300, P0301 P0302 P0303 P0304. Clear all codes and they'll be back after 20-30 miles.
Car runs fine , I can't feel any sort of misfire, idles fine hot or cold and accelerates as it always has.
The wife had a citroen with a misfire which totally destroyed the cat so wary of driving the Audi with any misfire.
Parts I've bought and replaced,
4 Bosch Coils and NGK plugs ( both from from eurocarparts)
Ebay PCV valve (both old and new seem ok)
Checked fuel pump follower, no wear
Where next?
Any help appreciated
Could well be injectors, Changed all 4 on an 10 plate Golf GTI for one of my work colleagues. He had similar issues, only 60K on the car. If you have VCDS you can see the misfire counters in the measuring blocks. His would misfire on idle and part throttle , perfect when flat out. Notice you are from Tammworth if you take it over to Nick at R-Tech in Nuneaton they will diagnose it for you definitively. They tune and repair these cars daily and have all the tools to clean and check injectors if required.
Quite often the filter basket on the injectors gets filled with debris, If it's had one of those carbon cleaning sessions where they run a cleaner through the injectors this can be quite aggressive and can lead to issues.

The injector clinic is part of R-Tech.
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Anything off balance can cause it to log a misfire, happened to me when my DMF started to fail
Thanks for the R-Tech recommendation, I was looking for somewhere decent, just wanted to change the bleedin obvious before I admit defeat

Dave, forgot they had a DMF, I've had DMF go on another car so I can see that happening
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If you have the 2.0TSI engine it could be the inlet manifold clogging up. Mine shows misfire codes occasionally when starting from cold although the engine runs smooth at all other times.
Best test to do is a live ignition test on a OBD2 or VCDS tester fromm cold start. If you see random misfires for just the first few minutes it's nowt to worry about, have the inlet manifold and valves cleaned.
This problem I think only affects the TSI E888 engines but may also affect other direct injection engines but I've not heard of any.
Update: problem fixed, took the car in , they recommended valve clean and injector check. , Injectors were fine and carbon build up not horrendous, noticed on dissasembly that the vacuum brake booster pipe was split ( right hand top of the engine). Done a good 300 miles since and no problems.
Moral of the story, check this first and you could save yourself £720.

Hope this helps someone
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