okay story car was running great its a n/a s4 even with over 200k on it it ran hard so one day of driving it like any other day (never pushing it only at last redlining it twice a week to break carbon build up) and i get home and park the car done. next day it wont start. has oil, has gas, new battery, has pretty much new spark plugs (1 month old) and once i played with it it would start great yay! now this i idles under 500rpms and its super sluggish when i press the gas. drops rpms faster. shuts off. the motor sounds louder then before. motor rocks as it idles. and smokes out gass lots of it. im really lost on this. does anyone know why it might be doing this??? im guessing it can be a ignition or fuel injector prob? idk HELP!!!!!!! this is my daily driver!!!!

 

First, eliminate the worst possible cause.

http://www.rotaryresurrection.com/2n...ion_check.html

 

Compression Check!

 

sounds like that motor is done.

 

200k is a good run though!

 

yea im about to go check the compression, but yea the day before all this happend it was running awesome and smooth. i just dont get why so sudden.

 

Ah, the calm before the storm, usually the car will run great and then die. Kinda like a dog that gets real playful then you find it dead under the porch the next day...

 

haha, well i did the compression test and it all seems good

 

If it still has the cats they might be clogged.
Run a bottle of injector cleaner thru it.

 

seems good? Did you the poor mans test or use a piston tester. I would recommend getting the piston tester and using that, more accurate results.