Maximus

well I see many threads about cels and K+N filters..........any car that runs a MAF sensor will likely be affected by this problem, some brands worse then others........the Tiburon had a problem as well........

what can happen with a K+N is that the oil from the K+N filter will collect on the MAF sensor wire and throw off its readings....when the MAF sensor wire is dirty the ecu will think your engine is running lean as it will compare your 02 sensor readings against your contaminated MAF

well the way to fix this is to very carefully clean your MAF sensor wire with a Q-Tip and alchohol......usualy this happens when a filter is brand new or you have cleaned it and over oiled it....some K+N kits allow you to apply the first oiling, which many people over do....any excess oil will be drawn into your intake tract and collect on the MAF sensor, completely throwing it out of whack...........as when the MAF reads a lower volume of incoming air(the symptom of being dirty) your ecu will pull fuel to accomodate, which will cause your engine to run lean throwing a code based off your 02 readings....

now GM has likely programmed the A/F parameters to be very strict since this is a boosted engine(lean can kill it) and this ecu is likely not tolerant of of any variations between MAF and 02 readings, throwing a cel at the first sign of trouble.

Fords suffer from this quite a bit as I learned this from a FORD mechanic, as FORD had a memo about K+N filters and comtaminated MAF sensors.....usualy after running for a while the K+N will dry out and not cause problems.....

So whatever you do do not over oil your filter, if you did let it dry in the sun for a few days before you install it

if your filter is new and looks over oiled let it dry for a while before installing it, as sometimes they are sealed in a package from factory and can be quite oily....this oil is designed to stick to dirt, so when the oil hits the MAF wire it doesn't take long for dirt to collect

ExHondaMan

GM i believe also has a memo about oil'd filters..

If you going to clean you MAF I would stress to be VERY careful.. its a very sensitive component...

tripwire1212000

To all those out there that have purchased a K&N CAI for their Cobalt SS, I have one thing to say, stick in there. K&N did a great job in the design of their CAI. I have first hand knowledge being one that has had my car on their dyno. The fuel correction in the Cobalt SS' range from 0%-15.5% on stock settings. With the K&N it ranges 0%-19.5% in ideal settings. Your check engine light is thrown at 20% correction, i.e. you are leaning out. I have an AEM CAI as well. AEM uses part of the factory intake system with their kit. The down side is the fact that AEM was unable to create a full tube design due to the limitation of room inside the engine bay. GM is coming out with stage kits as of the first quarter, starting January 1st 2006. My advice if you want some great power out of your Cobalt SS, is to purchase the stage kit with the injectors and reflash of the ECM. Get yourself a K&N CAI, and try putting a pulley with dia of 2.85". The factory exhaust is great upto about 300hp. There is no need to go bigger until you reach that stage of the game. If you do, you will most likely be losing power. Happy racing!

Jmc007

Some nice advices, but could you explain us how we could lose power by upgrading to a bigger exhaust ????? ((O))((O))

undrgrndcobalt

tomuch flowing out,not enough engine to feed the exhaust, had this problem on my Honda CRX, went from stock 2 inch piping to 3 inch and lost a **** load of power...

Cobalt_Supercharged

Free flow exhausts allow you to gain hp, but the engine needs some back pressure to create torque. At least that is the theory I heard.

ExHondaMan

Im assuming your CRX was also NA...... I know on atleast on a turbo car bigger is 99.5% of the item better... I really wish I understood or had a source from which to learn about 4cyl SC exhaust theory... cause I cant imagine the same rules apply as a NA car...

ExHondaMan

..... Sorry couldn't help myself.

Jmc007

OK here is something to read about the exhaust and the backpressure myth ...

http://www.popularhotrodding.com/eng...re/0505em_exh/