I have a civic type r motor and the stock jdm 4-2-1 header with a 2.5 inch collector, and on the end of that is a 2 1/4 catco cat that has a donut gasket flared out to fit the 2.5 header and then on the other side of the cat i have apexi n1 exhaust. Am i creating back pressure due to 2 1/4 cat and/or is this affecting my car in acceleration? My car feels like a slug at low rpm's, and even when vtec kicks in it doesnt pull as hard sometimes. Its really weird it doesnt happen all the time but its kinda like something is holding it back from moving. If the 2/14 cat isnt slowing it down how do u check for a clogged cat, or what else should i check for? Any input would be greatly appriciated.....thanks in advance!

 

Are you throwing any codes at all? Sounds like the O2 sensor is giving out or is not wired up properly.

Either that, or spark plugs/wires, cap/rotor, non properly gapped plugs, or shitty gas.

Keep us posted.

 

Nah, im not throwing any codes at all. Will the 2 1/4 inch cat affect my car since i have a 2.5 collector header though?

 

That could be the cause of your bog at lower RPM's due to no back pressure. But top end should pull..

 

well the motor is practically brand new so i dont think i need a new cap and rotor, and the plugs and wires are new as well. I havent thrown any codes at all but vtec doesnt sound the same and it defidently doesnt pull, oh and by the way i dont know why but i have to put a quart of oil in my car like ever week, someone please help, what could this be? clogged cat not right size cat? whats burning up all this oil?

 

If your cat is clogging then you will have excessive backpressure. Especially when going up hills etc... If you are getting oil down into the manifold and into the cat, it will plug and cause troble. This will also adversely affect your 02 sensors causing them to be lazy or even faulty. Thus not throwing a code as quickly as it should, or adjusting the Air/Fuel ratio as as well.