question about non fouler spark plug trick with test pipes

0

05fx35black

Member
Location
Manhattan
So I've been contemplating test pipes with resonators (my state does not have emissions) I was wondering about the non fouler spark plug trick. To my understanding, by doing this less oxygen is measured basically tricking the ecu to thinking the a/f is richer than it is thus leaning out the mix. Has anybody have any performance issues with this? Are the a/f ratios still safe? and is a flex joint on the test pipe necessary. I looked at fast intentions and theirs doesn't have a flex joint. Megan racing has resonators, and extender already welded on the o2 bung, and flex joint. Ebay test pipe has resonator and no flex. FYI Thanks in advance
 
You're correct about how the non fouler works. Not sure if any problems arise from them though. Most tp's don't have flex joints, and neither do high flow cats.
 
Wait, sorry, you were wrong haha. The non fouler moves the O2 meter farther away not to affect the engine, but just to keep you from getting a CEL because it is picking up different readings.
 
Exactly, it's the SECONDARY o2 sensors which have little to do with vehicle performance (and nothing to do with air/fuel mixture) that you're trying to trick into thinking a catalytic converter is present.

The sensors' only function is to make sure the cats are doing their job, and if they're not (either too high a signal from cats not being present or deteriorated, too low from the cats being clogged) it'll store a diagnostic trouble code and throw a Check Engine Light.

My brother had the non-foulers on his Megan test pipes and as far as I'm aware they worked fine (no CEL), though the test pipes themselves went bad and the internal resonators started to rattle so the stock cats went back on.
 
Last edited:
OK thanks a lot for the info i was not aware of how many O2 sensors there were. This is my first OBDII car! This will officially make it three cars I've owned that didn't have cats. Sorry if I offend anybody at least the other two cars were turbo.
 
You must log in or register to reply here.
Back
Top