well tonight i took my s4 t2 out for a drive and i boosted it a couple times and it was running great...then i noticed the tach went out on me... and the next time i boosted it as soon as it spooled up the engine boged down and i heard a really rapid backfiring sound coming from the exhaust...so i left off the gas and it seems to cruise fine but as soon as you get on it it makes that backfiring sound and it looses all power....any help would be greatly appreciated.. i hope i described the problem well enough to get some answers....

 

loose or bad plug wires, bad spark wires, not enough fuel and running lean, it can be a lot of things.

 

its a brand new motor i have new plugs and wires and i have a wideband wich was reading in the 10's when it was doin it...any other ideas?

 

10's? That's rich. Did you tach ever start working?

 

10's? That's rich. Did your tach ever start working?

 

yeah the tach is working now....i know 10's is rich but my safc is fucked up and i havent got a chance to get it dyno tuned yet and it ran ok before when it was runnin in the 10's....i drove the car again today and it runs great below 3000 rpm but as soon as it trys to build boost it just starts bucking and backfiring....im clueless as to whats wrong...

 

ok wtf i had a quarter tank of gas left so i decided to go fill up..i filled the tank and drove off and the car runs fine wtf could have caused that?

 

My car is doing the same exact thing right now just came outa nowhere but i got hella gas and it hasnt fixed it...its the same problem you described..im about to put mine back in the shop