Hey guys, i have a 90 NA with 152K miles. I bought it last year with 76K miles. I've changed the plugs 3 or 4 times since I owned the car, everytime I would get plugs that have that tanish look. Since the first time I changed my plugs, I have gutted my cats and changed to a higher flow muffler, but the result is the same thing. The plugs would still look tan, so I am thinking that I am running on the lean side, is there a way for me to turn up the mixture just a little to get more fuel in? Also help me gaina few hp... Thanks

 

86-88 cars had a rich/lean screw on the passenger fenderwell, near the airbox. I don't know about the 89-91 cars though.

 

 

You try running a higher octane gas? Richening up the mixture wont give you more HP, its the other way around.

 

Try changing the fuel filter yet? Other than doing the maintainance stuffs, remapping the ECU ROM or S-AFC is another method. I don't think there is a cheaper way for our S5 cars. Jay