lakoe

So i've got a manual 2008 s5 with the 4.2L v8 and i was just looking for some insight on some misfires ive been getting. Firstly, ive had the car for around 5 months now and it has 101500 miles and around a month or so ago I got a cylinder 1 misfire so i did some researching and figured I have no clue the last time someone changed the plugs so i went ahead and bought 8 new NGK plugs and installed them, after that I immediately got cylinder 1, 2 and 4 misfires and a engine fault for Knock Sensor 4 (signal too low) and obviously a multiple cylinder fault. So I looked to see if anything was loose or i forgot to plug anything in or whatever and it was good, so i switched over the ignition packs around and unfortunately the misfires did not follow so im guessing it needs a carbon clean and new fuel injectors. this would be the first time ive done serious work on the engine of a car but im interested in replacing them myself if i can be more sure its the injectors that need replacing. Some more information about how the car drives - doesn't get as roudy as it used to, a little quieter, no rough idle but when i speed up it has nowhere near the same power and car starts shaking. Any advice or knowledge would be appreciated!

Also one more thing I was researching fuel injectors and saw these on ebay from a guy with a high rating and 4000+ reviews selling (https://shorturl.at/aeAU9) a set of 4 fuel injectors for $85 and it seems way too good to be true comparing to the next cheapest price being $500 for 8 being remanufactured ones from rockauto. But i looked up the part number and they come back on ECStuning fitting my car and being $150 per one injector so does anyone know if this is a scam or something?

Thanks

hahnmgh63

This is the reseal kit I'm showing from FCP Euro and it's guaranteed for life: https://www.fcpeuro.com/products/aud...t6#description newest Audi part # for one injector is 06E-998-907-G
I wouldn't buy Chinese injectors for sure. If it isn't your only car pull it apart first and inspect the injectors, you may be able to send them out for cleaning and flow testing.
Latest injector part # is 079-906-036-AA replaces part 079-906-036-C

lakoe

Thanks for the reply, what if i dont plan on keeping the car a long time and just want to get rid of the misfires?

hahnmgh63

Injectors may be fine, may just need a carbon clean. Really won't know until you get the Intake manifold off. How did the old plugs look when you pulled them off?

lakoe

Ah i see, plugs didnt really look that bad, they were just covered in oil so the gaskets need replacing too.