o2 sensor spacer

[JITB]

Does this work for eliminating cel codes in catless exhaust for the msp? I know some cars it works, and some doesnt.

 

[destineal]

If it moves the o2 sensor further out of the exhaust stream then yes.

 

[CiviCity]

What piece do i need to make a non fouler? From where can i buy it since im in canada?

 

[xxxmonoxidechil]

they sell them. you dont have to make it. Just go to any auto parts store, and ask for a spark plug non fouler. I had to drill mine out a little to clear the O2 sensor, but it did get rid of the O2 sensor code on my Mazda6, and even on my old Hyundai tiburon also.

 

[YlwMSP]

You also have to make sure it doesn't move the O2 sensor out too far, or it will still set a code for "weak or no signal from secondary O2 sensor"

 

[jeremy irons]

is the second o2 sensor even part of a closed loop? i wonder why it couldn't just be replaced with a couple of resistors to spoof the load and a .55v signal.

 

[JDMazdaFamilia]

Yes, the second o2 sensor is part of closed loop. I would assume you can't do a fake signal because the PCM will still catch it and throw a code. The PCM will dump fuel for a split second to see if the downstream o2 reports cat operation

 

[tweety2300]

The second o2 sensor does nothing but monitor the Pre cat, it does not monitor fuel ( unless the msp is different than a regular protege which is highly doubtful) people have used resistors on regular protgs with no issues

 

[JITB]

Yea i have plenty non foulers from my other cars, but has anyone tried it on a msp? If not im gonna have to register my car in alabama lol

 

[J_Naoto]

it worked for me when i was completely catless. do it!

 

[mxjosh82]

Yes it works on MSP. I have one on my 3in catless exhaust, no codes

 

[hornsfan10609]

I have the generic non-fouler from autozone on my catless midpipe, never had a CEL it works great.

 

[JITB]

perfect! you all didnt have to trim it or anything for it to read right?

 

[hornsfan10609]

Nope, that's really all there is to it.

 

[jdwk]

The catalytic converted will convert more oxygen into carbon dioxide effectively making the exhaust more "rich". Narrowband O2 sensors like we have will read around .5v at stoich. As more oxygen is available due to running lean it will read lower voltage. If you remove the oxygen by adding more fuel it will read a higher voltage.

The PCM makes sure the cat is working by checking that the voltage from the secondary O2 is higher than the voltage from the primary. If you space the secondary O2 out of the exhaust stream a bit, it will have less exhaust pass over it and therefore come in contact with less oxygen and have a higher voltage than the primary and all is well. Too far and it won't get any oxygen and you will trip a code for a bad rear O2. I don't know if giving it a constant .55v will work since I've read the PCM still expects it to drop below .5v when the mixture goes lean.

JDMazdaFamilia, I am not sure where you got the idea that the PCM adds fuel to test the rear O2, but I have seen no evidence of it while monitoring my car, nor does it make any sense since a functional cat would already appear as a richer mixture to the rear O2. But I've been surprised before by this car, so maybe I missed something.

 

[hornsfan10609]

The only Mazdas I am aware of that have an actual O2 sensor 'test' is the 2010+ Speed3's. That is why they always throw a CEL when a catless DP is installed on the 2nd gens. These cars have WB02 sensors from the factory.