Spark Plug Defouler?
 

2001 Monte Carlo SS 3.8L

OK I'm close to getting my aftermarket catalytic converter exchanged out under warranty. To keep this code from popping up on the new one I'm going to use the spark plug defouler trick. Now for my question? Do I need to modify this spark plug defouler in anyway? I see on some other forums guys are drilling these out and cutting the shrouds off the tip and other crazy things. Do I need to do all that? Anyone that has done this trick do I just screw the O2 sensor into this and then screw it into the exhaust pipe? With no mods needed I hope?

Thanks guys. :thumbsup:

I have not done this, but I researched it as a low cost solution before I swapped my down pipe for a ZZP down pipe with u-bend delete and high flow cat.

My research found:
- You might need 2 defoulers (try one, if it doesn't work, try 2).
- Only one defouler needs bored out (drill it out so the O2 probe will fit into it).
- Should screw right in. Part of the idea behind this is that the defoulers use the same thread type as the O2 sensor.

Hope that helps a little.

OK great that gives me what I need. So these tutorials on "drilling" out the end of it so the O2 sensor fits into it are true.

Will two of them fit though? I'm trying to remember the way that back one is positioned and isn't it towards the top and angled toward the underside of the car? I'm wondering it two wouldn't make it too long and make it hit the underside the car? I'll have to crawl under and look when it gets nicer out.

Yes two will fit I did this on my 2005 Monte SS Supercharged when I installed headers.. It worked but I didn't like the drone noise from the headers with out cat .. So I removed headers an installed a power log..

So if we can have the code removed from the PCM, Why go through all this trouble? Or did I miss something? :confused:

Cost. The defouler costs like $10 for a pair from most parts stores. There is a O2 emulator that works up to an '03 but that is like $50.

PCM adjustment costs are typically over $100 regardless of what you have done. Most people making any PCM adjustments are using a HP Tuner to edit a car, it takes I think 2 credits per car, cost per credit is like $100 (don't quote that as exact) or unlock all cars of that model for that year for a one time cost of credits.

The service I offer of $50, I'm using a DHP PowrTuner. DHP went out of business, therefore unlike HP Tuners, if my device does not read the version of the software on the PCM, I need to source a compatible file that DHP unlocked before they went under. But I have no credit costs, I can make adjustments to as many cars as I want that DHP supported. What I offer for $50 is basic settings adjustments (not a full tune like ZZP, Overkill or the others).

Hope that was more then you asked for lol :)

Thanks Maniac.

@ JC Colon' yeah its mainly cost and the fact that I'd have to send out the PCM to get the code tuned out. This is my daily driver vehicle and I'm in my senior year of a CIS Networking degree so I can't afford to miss classes while I'm waiting for the PCM to be returned.

I actually think the 18 MM (which I believe fits) is only about $5.99 for a pair at the local Autozone.

HPTuners does require 2 credits for our cars, each credit is $50 though. :thumbsup:

Heres a video that shows you exactly how to do it..


:wave&point:

Excellent I love videos.

So Maniac says to try one first and if I do that do I used the drilled out one first? Then if it doesn't work add the second one in?

Does anyone know for sure if I need two right off or will one work?