I installed a K&N air filter on a stock 2000 Protege LX (1.6L). There is good and bad. First the good:

- My gas mileage went up to 36.32 on my last tank.
- The change seems to have added A LOT more power (I don't know how much since I haven't dyno'd it)

Ok, now the bad:
This may be totally unrelated but it started at the same time, and seems like it has gotten worse. On medium and heavy acceleration, and between 3.5k and 4.5k on the tach, the car jerks a lot in the same way a deisel truck jerks when you take off in first and don't need to. Does anyone have guesses on what is causing this? My thought was that installing the K&N filter messed with the fuel air mixture and the computer/injectors are having issues compensating. At first I thought the injectors might be a little dirty, and I added a bottle of injector cleanerat a fill up, but that hasn't seemed to stop it fromgetting worse.

Any ideas?

 

Did you put silicone or oil on the filter when you installed it? If so clean your MAF hotwire. Do not use silicone or oil on the filter as silicone destroys o2 sensors and oil gets on the MAF hotwire and gives false readings to the PCM.