solution: Check engine light w/ aftermarket Headers

I think there are a few things wrong with capping it. First, I believe if you cut the oxygen sensor totally away from the exhaust stream, it will throw a code. So that eliminates capping it.

If you don't take it far enough away from the stream, you will still get exhaust strong enough flowing over the O2 sensor to throw a CEL for catalytic innefficiency. So I don't think you can cap it with holes in the cap.

Besides that, even if it did work, you would have to find/manufacture a cap that could withstand the heat of the exhaust, still plug into the bung holes, and fit over the O2 tip.

Why try and find a solution to a problem in where there is already an easy solution? If you can't fit it due to a transmission, you can pay an exhaust/performance/dyno shop $50-65 to make a new location for you. Most performance shops have to make one anyways for a wideband sensor anyways.

It's been 2-3 months with only one CEL when I drove over 200+ miles. Daily driving does not set it off at all. Good enough to pass an OBD scan for emissions, good enough for me.

Minnoe07, thanks for the response.

Yeah don't fix it if it (the nonfouler solution) ain't broke right?

I was going to try the nonfoulers this weekend either way, but I couldn't help asking myself "what if i just ... ?"

But i'm sure, while working on my car this weekend, i'll run into a lot of "oh that's why i can't ..." or "oh that's what they were talking about" and eventually "man, i must've sounded like an idiot on the forum"

knew i was being too naive about this, just needed someone to point it out for me lol. we'll see how it goes...

This is a great idea. Just curious if this only take away the CEL but still won't pass the smog? Or can you also pass smog even with headers?

Originally Posted by hyunman

quick question...planning on doing this to my beater accord but...

in essence, seems like this diy is basically pulling the o2 sensor out of the main stream of exhaust, so it doesn't "see" the fumes as much...but if such a simple fix overcomes a lot of these CEL errors...what's there to say that putting something over the o2 sensor won't accomplish the same or similar effect? for example (just grabbing some ideas out of the blue)...what if i pulled out the o2 sensor and placed a metal cap or lid over the o2 sensor, and plugged it back in? perhaps poke a few holes in the metal cap so that it's not TOO restricting...would something like this do the trick as well?

i haven't pulled my o2 sensor out yet, and have never even seen one in real life - all i know about o2 sensors are from what i've seen online. so forgive me if i'm missing something obvious. i'm more than willing to try this non-fouler diy but wanted to throw this out there before trying it.

O2's generate voltage based on oxygen in the air. Once they are heated up the produce less then 1volt. The higher the voltage the more rich the mixture is. They are VERY sensitive to changes. If you block it off... You will have low voltage and get a CEL for that. Also that would make your car run RICH and waste gas. I wouldn't' block it off.

BTW my CEL came on today on the drive home from work. I'll post back how long it takes to run off. I have already noticed increased gas mileage (for the better) as well as a lot more power thru all gears and RPM's. Pulls much harder from 3rd-4th. I need to put some some cats on to get rid of the smell, and stop polluting of course. If anyone is interested... stock pipes are 2", and up for sale. -- PM me if interested.

Instead of stacking these two parts together for the defouler method, couldn't a similar item be manufactured by a machine shop to put the o2 sensor at more of a right angle for ease of installation.

When I had my CEL pop during my 200+ mile trip, it never turned off. I went to the local autozone and cleared it with a code reader. It hasn't come back in over a month. For some reason, and I don't know what, long road trips are the only things that seem to make the CEL come on, which is fine with me since I only need to pass an OBD scan for emissions and I rarely take long road trips.

If you have to pass smog (a.k.a. tail pipe sniffer) these non-foulers will do absolutely nothing for you.

Non-foulers are only for the people in states where all you have to do is pass an OBD readiness test. They plug up to your OBD and scan for any codes. Any codes = fail. If you clear codes and go get tested too soon = fail. These non-foulers will keep your CEL light from coming on = pass.

The right angle idea might work. Just need a person skilled enough to do that. I don't know if that will be enough to keep the CEL from popping though. You can always try and find out.

I think I might buy these instead :
http://cgi.ebay.com/ebaymotors/Pair-...mZ130240825822

Originally Posted by fmzip

I think I might buy these instead :
http://cgi.ebay.com/ebaymotors/Pair-...mZ130240825822

Fifty bucks for a set of non-foulers.... WOW!!!!!!!!

Originally Posted by frobie15

Fifty bucks for a set of non-foulers.... WOW!!!!!!!!

50$!! Thats rediclious. If your worried about drilling them out... its not that difficult. C-clamp and some drill bits; 1/2" drill bit on 2 of the defoulers is the goal and then screw the others ones in the bottom. You could probably get 2 sets of small ones and call it good.

I think my problem with the CEL is that I drilled the bottom defouler out to 3/8" (i think it was 3/8")... so its not working quite as good as it should be.... o well. I honestly dont think changing defoulers would be very hard if I used a lift.

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FYI:
If anyone is interested... the stock exhaust manifold weights 23lbs. short side=10lbs and long side=13lbs. SS ones weight around 8 lbs. So you cut a little bit of weight from the car. Add 2 cats and ur prolly around 12-13lbs total. So about 10lbs lost. Not too bad.

Originally Posted by zvinzonz

This is a great idea. Just curious if this only take away the CEL but still won't pass the smog? Or can you also pass smog even with headers?

defoulers are to trick the rear o2's... In no way shape or form will it help you pass emissions! You will 100% fail if you don't put cats further down the line. This of course talking about emission checks where they put a hose on your tail pipe.

e46's have 3 cat's, 2 on the headers and 1 down stream. The one down stream doesnt do too much.

My car only has that 1 cat downstream right now and it stinks really bad! The exhaust temp also went up a LOT. You will defiantly want to buy some(2) universal cats ( jegs or summitracing I've found have good prices). My stock manifold flanges were 2" on my 03 330xi... Im' not sure if all 330's are the same or not. My guess is no.

i had the non foulers custome made and my CEL is still on. i need the software.

Originally Posted by pish180

defoulers are to trick the rear o2's... In no way shape or form will it help you pass emissions! You will 100% fail if you don't put cats further down the line. This of course talking about emission checks where they put a hose on your tail pipe.

e46's have 3 cat's, 2 on the headers and 1 down stream. The one down stream doesnt do too much.

My car only has that 1 cat downstream right now and it stinks really bad! The exhaust temp also went up a LOT. You will defiantly want to buy some(2) universal cats ( jegs or summitracing I've found have good prices). My stock manifold flanges were 2" on my 03 330xi... Im' not sure if all 330's are the same or not. My guess is no.

I am putting cat on it since I'm in California. Maybe I should rephrase my question if by putting the defouler is it possible to trick the smog station computer. And i think they still put hose on the tailpipe here in California.

No, you cannot trick it. Like I said, this is only for people who have to do OBD scans only. You need cats in order to pass smog.

so you need 4 of those non-foulers for M3, since there are 2 rear 02 sensors?

Originally Posted by Boostin FD

so you need 4 of those non-foulers for M3, since there are 2 rear 02 sensors?

Thats correct. The DIY says 2 short (1 package) and 2 long ( 1 package). Although I think you may be able to get away with 2 shorts for clearance issues.

You will need to drill two of them out to 1/2" so the o2's will screw in all the way. Don't just stick a 1/2 bit on an start going.. you will need like 3 sizes in-between to gradually get larger.

non foulers didnt work for me,light is still on.

Originally Posted by n2Bimmer

non foulers didnt work for me,light is still on.

me either. I still have a light even with aftermarket cats!

Originally Posted by n2Bimmer

non foulers didnt work for me,light is still on.

still on?? did you clear the codes first? The light wont turn off by itself. Go to autozone and have them clear the codes. OBD2 hookup is right above the dead pedal.

Originally Posted by frobie15

me either. I still have a light even with aftermarket cats!

Did you relocate your O2's? Otherwise aftermarket cats wouldn't do anything to affect the O2 readings. And if you did relocate them... how far down? Making the wire longer creates more resistance, giving the reading less voltage. My guess would be you don't get cat inefficiency if you did that, you would get something else. You'd also lose fuel economy.

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My setup works for about 100 miles and then comes back on. But i drilled out 1 set of foulers to 1/2" and the other set to 3/8". And I was only suppose to drill out the 1 set to 1/2".

Ill just have to buy some new ones and take it too a lift to install them.

I think my biggest issue stems from how the O2's were installed. Angled down. Lame.

I just went at it straight with a 1/2 in drill bit. No problem.