Boostedmx606

Hello everyone. I may be new to this forum but i am no stranger to working on all sorts of random cool cars. I just recently decided to buy a 2005 Audi A4 3.0 from a friend who owns a dealership. He told me $6000 and the car is mine, no rust, no dents ect. However, the deal was is that i had to fix all the check engine lights in order to purchase the car. When i scanned it, it had about 7 check engine lights. I cleared the codes and stared it and it all came back again. Cylinder misfire 1-6 and multiple cylinder misfires. I went ahead and purchased 6 spark plugs and 6 coils along with a MAF sensor. I installed all of them, cleared the codes and started it up... no check engine lights. Drove around the block, no check engine lights. Drove 15 miles and still no CEL however i hooked up to my scanner and had 3 misfire codes pending. I cleared them, drove the car for 35 miles, all but 1 monitor was ready and i got it inspected.... I thought everything was great. Next day, i started it back up and it threw a CEL light and 7 codes popped up again, all for cylinder misfires. At this point, i dont want to pull the parts shotgun out and start replacing every sensor but i have no idea what to do now. Please, does anyone have any idea on what is going on. New plugs, coils and MAF and same problem. PS. i this car runs and drives great, there is no actualy noticeable misfires, it doesnt hesistate, pop, spit, sputter or anything. i never actually witnessed a misfire. I just cleared the codes and drove 25 miles and still no cel. Ugh

a44me2

check all vacuum lines! it is common on these engines to have minor vacuum leaks, and they do not always show as a bobbing rpm. I also recomend checking the pcv system for cracked lines or build up in the valve and lines. When was the fuel filter last changed? Maybe fuel pressure is low?

Boostedmx606

Ok,ill start looking at vacuum lines. I am not sure when the fuel filter was replaced yet, however id have to assume it was well taken care of because the timing belt looks brand new. I work at a carquest and am literally picking up a fuel filter now to try. A vacuum leak could cause that many cels?

a44me2

yes, i have seen multiple misfire codes from a bad gasket on the oil fill cap!

ct_esq

vac lines are likely culprits as well as the cam position sensor.

if you changed all the coil packs, and the plugs (i think you said you did in the OP) vac issues and the cam pos sensor are in the mix.