need some help guys please :xhelp:

[benny]

its mot time again, and im struggling on the emissions, to be honest its struggled for the last couple of years no matter what mods ive added so i know its not my mods hks silent, rbc, aem, dc sports mani(which gets replaced with the cat), kpro, when i first got the car it only had the exhaust and it still struggled
right the problem is -
i put the cat back on it and on the low idle speed it fails, but on the high idle it passes
ive spoke to a cat expert about gettin it repaired and he said dont bother as its not the cat other wise it would fail on the fast idle too
ive spoke to paul at tdi and he says as its a closed loop fueling system it cant be the engine as its all controlled by the ecu and cant be changed
when the o2 sensor is plugged back in i get no fault codes tellin me thats kapput, im at kinda a loss as what to do, and i cant do what i did last year so how do i get the low speed emissions down?
ive been told by a mate who used to have a nissan 200 that his sturuggled so they put tape round his air filter to restrict the air? and that worked for him, but surely with k-pro that would just add more fuel to compensate and make it richer which would make things worse!
there doesnt seam to be an issue with the drive of the car or the acceleration, and it does well mpg 40 on a trip to london! wtf is wrong???? please help
anyone got any ideas of similar issues what did you do?

 

[kyledc5]

if your modded exhaust alows very little back pressure then this would cause higher emissions at idle,i had this with my a few of my modded cars,and figured,to increase back pressure the exhaust needed to be restricted,as it was very free to flow.so i bought one of the exhaust bungs from ebay,fitted it and it worked a treat.just measure the diameter of your tailpipe,order the bung and try it,they are not exspensive,and they bolt into the tailpipe,that is if there a small hole on the side of the tailpipe,for the bolt,otherwise drill it.this is sure to work mate.

 

[C&S Evo7]

you need to do ecu reset after refitting your cat too, if that fails the bung idea sounds reasonable, i have a hks one here if you pm me the inner tailpipe diameter and the actual exhaust inner diameter (the bit that exits into the tailpipe) if it matches you can borrow it if you cover the postage ??

 

[benny]

thanks guys, ill give it a go, and get the measurements cant do anyharm and there seams no other way of making it pass. ill give you a shout if i need that bung evo7 really appriacate it.