Try resetting your ecu - probably with additional air the afr/ timing is messed up

what engine on what car? maybe due to engine mounting because your engine produce more power...

just to let u know..the filteration is very poor tho....i've used it for 1K km, and found out my airbox and pipe leading to TB was covered by thick dust...

Timing is out. Probably as mentioned rakyat. Reset/adjust ecu should solve d issue

Stainless steel filters without mesh is only meant to be used on track where it is driving for short amount of distance before the engine is stripped down and overhauled. To use it daily in a road car will eventually damage your engine.

On other high flow filters, there is a cotton mesh/filter sandwiched between the steel mesh. Filters like K&N will require applying a little oil on the cotton mesh so that it can trap the smaller particles of dust.

Most stainless steel filters don't come with the cotton net in between, meaning your entire filter is made of stainless steel only. This is gives super highflow but suitable for track use only. Some company will make this into a drop in filter hoping that people will think that it can be used on the road. These companies don't do any R&D or testing before selling these products.

No it would not help as you don't have the cotton mesh to hold the oil. You'd just end up sucking the oil into the engine.

The next time you go to any car accessories shop, take a closer look at K&N filters and you'd know what I mean.

The ECU is using your old ratio of 1X air hence pump 1Y petrol, with your new intake you are sucking 1.5X air but still pumping 1Y petrol hence your timing or Air/Fuel ratio is 'out'.  Your ECU need to relearn the ratio, it does not mean your ECU is rosak

Don't need to go to w/s , just disconnect the clock fuse (if you know where it is) or disconnect you battery terminal (-ve) for 10 minutes and reconnect, go for a spirited drive (rev hard afew times) and the engine should run smoothly.

I didn't say I was using the same filter for 10 years. In the last 10 years I have used 3 different K&N filters in 2 different cars.

---

Added on June 2, 2010, 2:02 pm
The air fuel ratio would not change with a simple air filter replacement. The mappings are still the same and for most road cars, the ECU is not very adaptive and will not make much difference whether you reset it or not. Furthermore, a lot of the ECUs cannot be reset by just taking out the car battery. Settings are coded into the ROM and even with the lost of power will not reset the ECU. Only by plugging in an on-board diagnostic tool can you reset it.