i have an 00 s4, chipped, it used to be awesome. lately, it seems like its running with no boost. i can't hear any leaks, i have diverter valves and a full silicone hose kit. it knocks and seems like its running lean and then way too rich. ive replaced the maf and spark plugs, that did nothing. any suggestions?

 

knocks huh? bad o2 sensor maybe giving faulty readings? get a VAG done and see if anything shows up

 

i scan the codes all the time, they just come up as misfires, sometimes system lean, sometimes rich...i drove it without the o2 sensors plugged in, along with pretty much every other sensor on the top of the engine and it still runs the same. i thought it might be a fuel issue, because my pump whines when the gas gets low (the filter is new) but it doesn't explain why sometimes its fast, other timesits got like 190 hp. my turbo timer always gives good a/f readings and calculates run time fine, so i think the oxygen sensors are okay. it used to act a little different. before if you floored it and it was not making power,you could let off the gas completely andfloor it again andit would go into high boost. lately, it's just been slow all the time, even on cool nights.

 

have you checked the coils and plugs?

 

Get a boost gauge? ide start there to determine boost problem or something else.

 

i have replaced the plugs, not the coilpacks. i guess i will have to get a boost gauge, does anyone make a matching one besides awe?

 

yeah, apr does i think, but it doesn't look as good imo

 

check the coilpacks, ECU could be screwy, try swapping it with a friends that has an s4 thats running well

 

Before you spend any more money on it, just replace the coolant temp sensor. It's like $17, & I bet it will do the trick.

 

the water temp gauge does read high when car idles for over a few minutes and always reads high after driving, sitting, and then starting like 10 mins later. where is that sensor located? is it on that bar behind the block? do i have to drain the system?