I have noticed a flat spot around 3000 rpm after I installed a 15% pulley and Brisk plugs. Car also has a Milltek exhaust but no other mods. You can drive right through it under full throttle , but when cruising at about 3000 rpm its pretty noticable. I have a "before cat" O2 sensor code but it's been there since putting exhaust on two years ago. Car starts and idles fine. Gas mileage stays around 28-30mpg so I haven't changed the O2 sensor yet.

Thoughts??

TIA

 

the car has the 02-04 software version
it is prone to this especially after upping the boost
changing the timing and a/f ratios will fix that issue

 

sounds good. whats the best way to get that done?

 

uh... call Jan and get the car tuned?



drew-

 

check your SC bypass valve...reach under it and activate the lever, it should be slightly tight and instantly return to normal, if it doesn't you have a broken spring...https://www.northamericanmotoring.co...ysis-pics.html

 

I have an early 2004 MY with a terrible flat spot in the same place now also. Under Part throttle, it feels like I have taken my foot off the gas, just past 3000-3200 RPM, then it comes back around 3700 give or take. Full throttle seesm like so issue. I have had a 15% pulley for years and it has only gotten really bad the last year or so. I have replaced the coil pack, plug wires and plugs and it seems like it might have changed it a bit in the exact revs it comes on at, but it is not really improved.

Is it as simple as a tune?

 

Yes

 

Yes, go with Jan. He'll get you fixed up.