okay.. so you may or may not have seen my threads around this site for boost leaks and such on my 2000 s4 6sp.. well .. i think i have found the culprit for all of my power loss and my whooshing noise. any techs out there with info is greatly appreciated.. a week or two ago i developed a misfire under load, soon after i installed my apr ecu.. i was on my way to a bonfire in the country and was about 45 min from home or so..so i continued on to the party and just drove it lightly.. but it still misfired on occasion or going up a steep grade.. then on the way home the same thing.. misfiring on occasion..so.. anywho.. got up the next day and decided to change out the spark plugs.. im a technician.. and so i didnt post anything about this(or i think not) .. i thought it wasnt a big deal since ive done countless tune ups on audis and vws.. so..did the tune up and found the culprit for the misfire.. the number 2 plug had apparently gotten some moisture in it and there was a carbon tract down the plug where it was missing..so install new plugs and bam.. misfire fixed..but.. it was soon after this that i noticed the whooshing noise on the passenger side, plus the lack of power that i thought i was supposed to have.. so im wondering.. the noise is on the passenger side, which was where the misfire was occuring.. so how long can you have an intermitten misfire occur without damaging the catalyst?? that is what my guess is to my problem.. but im not sure.. .. hrm.. now with other cars that ive worked with.. it could be missing for about and hour and clog the cat.. some cars were driven weeks with a miss and still didnt clog the cat.. so whats the rule of thumb on my s4 with an apr tune??? i had planned to gut the cats anyhow.. so my plans will just be put in motion i guess..so all of my boost leaks are fixed... as ive checked my numbers with others with an apr tune and boost levels seem equivalent.. and this would explain why the cars boost in first gear is limited .. its trying to force exhaust through alot faster than the other gears.. so its not as noticable in the higher gears.. from 1500 to 6000 in first gear probably takes 2 seconds. then from the same 1500 to 6000 in third gear probably takes twice as long.. hrm.. just trying to figure this one out...im gonna post the same in the s4 threads...

 

cats do NOT get clogged from misfires

 

lol... yes they do.. no spark means fuel dumped into the exhaust. then that goes to the cat and its not supposed to do away with raw fuel ..ive seen it a hundred times.. itll clog them up in a heart beat..you know when the check engine light is flashing during a misfire?? thats called a catalyst damaging misfire.. unburned fuel gets super heated in the catalyst and will cause it to clog.. i dont even know who would have told you otherwise.. are you an audi oil change tech??

 

catalyst DAMAGING misfire.... is not a cataylst CLOGGING misfire.

"unburned fuel gets super heated in the catalyst and will cause it to clog"

doesn't clog... it super heats and breaks downs the special minerals used to strip harmful molecules from exhaust air.

making the catalyst less efficient... until it no longer performs at all...

doesn't clog, cause the airflow is still the same.


"and this would explain why the cars boost in first gear is limited .. its trying to force exhaust through alot faster than the other gears"

this makes no sense at all. exhaust is not being forced faster in first then third. see on the back of your engine, is a transmission. transmissions have gears. first gear in a transmission is known as a "short" gear. air doesn't flow faster. vacuum is still the same. boost is still the same. so airflow is still the same. the engine doesn't dictate the output of the transmission... the transmission dictates the out of the engine.

your loss of power in first gear most likely has more to do your tune being fucked up than your catalytic converter being clogged from an intermittent misfire.

and yes i am an audi tech, and i am very good. and remember your the one posting asking for help. not me

 

when the unburned fuel goes into the cat and gets super hot yes it does strip the minerals and has a melting effect.. and IT WILL MELT THE INSIDE OF A CAT AND CLOG IT. ive seen it a number of times... and your quip about the transmission was pretty funny.. but wouldnt you agree that your engine picks up speed faster in first gear, than in second and then again second goes through the revs faster than it does in third.. so guess what.. the engine produces the same amount of exhaust at a given rpm.. so when you go through 1st gear faster than you do in 2nd then the same amount of exhaust is moved through the same pipe IN LESS TIME!!! so an ubstruction in the exhaust will be more noticable for the higher speed flow... and how would my tune being fucked up cause a rustling noise on the passenger side of the car..
and yes i am the one asking for help.. for a 12th grade answer..
i didnt know 2nd graders had access to this site....