nice_tan

Hey guys... so my check engine light came on today and luckily I was visiting my mechanic for other reasons. He scanned my car and the o2 popped up. He mentioned that I should just go buy a test pipe and he'll add a extension to the o2 sensor so the code wont come up again. Did some searching but got confused about it. So wanted to ask you guys what might be a good choice for me. My current setup: Mugen 4-1 header and Fujitsubo RM-01A Exhaust. From my search mugen header is 2.5" and Fujitsubo RM-01A piping is 2.38". From what I remember, the previous owner said he put SMSP cat on the car. It was night time and he was closing so we didnt have the chance to lift the car. Just took a glance below and it looks like a regular stock cat. From my search, i believe gsr header are shorter so it will need a longer test pipe. And mugen/itr headers are longer so it needs a shorter test pipe. Is this true? if so, what test pipe do you guys recommend? Does it matter how long the test pipe has to be? I don't care about gain or sound, I just don't like seeing the engine light on. Also, would a 2.5" test pipe work?

cumminR

a test pipe will not in anyway shape or form fix a check engine light for a o2 sensor .....whats the code?

nice_tan

blah... didn't ask. I had an s2k before with same issue. test pipe worked for the s2k though. no code.
I'm assuming the problem occurs either on a bad cat or bad o2 sensor. And my guess is, my mechanic think its the bad cat.

Xian

If you use an anti-fouler (spacer), it should eliminate the code. Yes, these can be combined with a test pipe or you could just knock out the car substrate if you're concerned that it's blocking things up.

nice_tan

that's exactly what I was going to do. But anyone has any recommendation on what test pipe for my current setup? Mugen 4-1 header and Fujitsubo RM-01A exhaust.

B serious

iTrader: (1)

Do you have any idea how terrible your car is going to sound with a test pipe?

You can just use an spark plug defouler in your stock cat.

You also need to get some information about which code this is. A test pipe will not make an O2 code go away. That's insane.

Your primary O2 sensor is used for fuel trim. If your code is for your PRIMARY O2 sensor, then no amount of test pipes or defoulers will ever work.

Your secondary O2 sensor measures the efficiency of the cat by checking oxygen levels in the exhaust stream AFTER the cat.

If your cat fails, the secondary O2 sensor will turn on the CEL because it will see too little oxygen in the exhaust stream.

If your CEL is on for the secondary O2 sensor, you can use a spark plug defouler to get it out of the exhaust stream. This will keep it from actually monitoring anything and you can fool it into thinking that the cat is working just fine.

You don't need a test pipe to do that. You can just install the defouler into your cat...or a test pipe...or a hollowed out cat...or whatever piece of piping that the secondary O2 sensor is in.

Find out what the code is first. You want to be sure you're "fixing" the right problem.

nice_tan

Thanks for the post B Serious. Forgot to mention, it is the secondary o2. NOT primary. Cleared out the code and hasn't seen it pop back up so I'll check on it again if it does. I'll slap in the defouler and see what happens. Just wanted to see what options people are running. And for sound, I had a test pipe on my previous s2000 with aftermarket exhaust. Honestly, i didn't notice the TP haha just the sound of the aftermarket exhaust.

B serious

iTrader: (1)

S2000's sound great with a test pipe...as do K series cars (with the right exhaust). The B series sounds like a wet fart through a test pipe.