P0421 CEL

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P0421 CEL

Postby slvrspd » Sat May 14, 2011 10:00 pm

Brian,
How long do you think the RS mid pipe's small cat will stand up..I keep getting the same P0421 code telling me the cat is not working properly.
Obviously with the Cosworth pushing more air through the cat will be toast sooner...have about 28,000km on the mid pipe now (SC has been in for 15,000)
How much can I expect to pay for replacing the cat innards?
2006 Silver NC ,GT,PP,HT,,FM Stage II Suspension,GWR header, midpipe,Q exhaust,Exedy clutch +flywheel,Cosworth S/C
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Re: P0421 CEL

Postby Brian » Sat May 14, 2011 11:12 pm

Depends entirely on the accuracy of the tune. Had one customer install his supercharger and tune his car to run 10.8 to 1 and his factory midpipe cat lasted one week. I told him he was too rich when he bought our midpipe as replacement....and a few weeks later when it was dead he admitted that he had done nothing to fix the tune. In contast, you have many more miles on yours and I must assume a more accurate tune from that but perhaps the code is telling you it is about done. Then again, I have the very FIRST Cosworth kit ever sold in mine with original cat and I have seen that same code 3 or 4 times over the last 2.5 years yet the converter seems okay. Thus, you might try just clearing it for now and see how soon it comes back because I am getting many months between episodes of that code. If already getting it with high frequency then perhaps have a local muffler shop put in a BIG converter (like something intended for a V8 car).
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Re: P0421 CEL

Postby slvrspd » Sun May 15, 2011 9:46 pm

Thanks Brian,
Good tune ,thanks to Michael Mann,got the timing issue fixed as well...only cam timing was off ,and since then actually less of this code but will still come up after longer highway drive(4-500 km)
Probably good idea now that the timing is good ,and the tuning sorted ,to get a new catalytic converter.
2006 Silver NC ,GT,PP,HT,,FM Stage II Suspension,GWR header, midpipe,Q exhaust,Exedy clutch +flywheel,Cosworth S/C
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Re: P0421 CEL

Postby Brian » Tue May 17, 2011 9:42 am

Mike's tunes are first class....have his tune in our 2007. So, indeed it may be simply reaching capacity limit of that converter.
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Re: P0421 CEL

Postby AZ Sun Lover » Sat May 21, 2011 10:48 am

Hmm......you might want to read link below.

http://forum.mpvclub.com/viewtopic.php? ... sc&start=0

When I called to ask if this would fix / help the issue CEL code P-0421 with MX-5 owners I was told I must be the only one getting this code.

Sorry but Why? :?
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Re: P0421 CEL

Postby Brian » Sat May 21, 2011 11:37 am

Dear AZ Sun Lover, comparing your normally aspirated NC to a supercharged NC is like comparing it to a Mustang or Corvette....there is NO comparison in the gas flow levels the supercharged guys get compared with the normally aspirated. For the supercharged and turbo guys the converters will get used up much faster, rather like brake pads and tires. The better the tune, the longer the cats will last....but either way their life cycle will be much shorter because the boosted cars are force feeding the cats MUCH more gas volume than they were designed to handle, MUCH more unburned hydrocarbons means more heat, etc. I know several turbo and supercharged NC owners running BIG cats that were designed for big block cars like a Camaro or Corvette....but they welded them into their NC system because they needed that big capacity for their boosted motors. Nonetheless, backing the sensor out of the stream of that gas flow with an anti-fouler plug can be helpful with the error code frequency on any NC.
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Re: P0421 CEL

Postby AZ Sun Lover » Sat May 21, 2011 3:16 pm

Brian wrote:Dear AZ Sun Lover, comparing your normally aspirated NC to a supercharged NC is like comparing it to a Mustang or Corvette....there is NO comparison in the gas flow levels the supercharged guys get compared with the normally aspirated. For the supercharged and turbo guys the converters will get used up much faster, rather like brake pads and tires. The better the tune, the longer the cats will last....but either way their life cycle will be much shorter because the boosted cars are force feeding the cats MUCH more gas volume than they were designed to handle, MUCH more unburned hydrocarbons means more heat, etc. I know several turbo and supercharged NC owners running BIG cats that were designed for big block cars like a Camaro or Corvette....but they welded them into their NC system because they needed that big capacity for their boosted motors. Nonetheless, backing the sensor out of the stream of that gas flow with an anti-fouler plug can be helpful with the error code frequency on any NC.


Brian,
I pulled the RS header I had before and sold it. I do miss the bit of HP the header gave the MX-5 and I have never seen such a well fitting & made header. So I was hoping the reason for P-0421 would be known by now. The header helped the MX-5 but I got sick and tired of CEL's. I have normally aspirated NC.
So I called asking if the spacer would work to keep the P-0421 from popping up. Looks like no one knows the true reason this code pops up.
I did want to try the RS header as the PPE adds the cat in the engine compartment (more heat) but I guess I have to go with a PPE header. They are just across town.

Sorry Brian,
AZ
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Re: P0421 CEL

Postby Brian » Sat May 21, 2011 3:32 pm

Beat that dead horse, beat it, beat it, and beat it some more! Seriously Randy, I am coming to your door for Halloween dressed as a blinking engine light because we know it will scare you to death. :P

You have made this point dozens of times now. Just the other day you made it again at Miata.net. And again several folks jumped up in that thread and said they don't get the code you got with their normally aspirated performance header installs. At this point the number of owners running normally aspirated with a performance header without having any code issues.... is THOUSANDS of owners. You don't seem to understand that you had something wrong on your install, with your custom wire extension job, perhaps a damaged sensor, or a wire that just never got fixed right, who knows..... Bottom line, I am sorry you never got it figured out and gave up and that a light has caused you so much stress that you feel the need to post about it weekly for the rest of your life. Some people need to stay stock, if a totally 100% harmless light is going to keep you up at night, I suggest avoid the risk and not ever again try a performance header.

We are the only stocking dealer for that PPE header, good unit...and indeed it means less chance of code, particularly if you put the second sensor out past the midpipe converter so that you have two converters between the two sensors (like the stock arrangement). But, I must warn you...that some autocrossers have had the PPE core fail...resulting in that light you hate so much! PPE has changed the design and the updated core materials seem to be lasting much better.....so far. But, there is always risk in trying things that only a few dozen have tried and in the long run it is possible the new PPE core will fail and give you a light. Seriously, if that risk is going to keep you up at night and post about it forever, perhaps it is not for you.

I suggest you try out a different attitude, one that embraces failure! Failure is often the BEST opportunity to learn, and try different things. When something breaks, I consider it an opportunity to improve upon the design. Obviously PPE feels the same. And so does Racing Beat. For example, those early extension wires for the O2 sensors had issues and broke regularly, and we worked with Racing Beat until a company was found that could deliver a much higher percentage of success and reliability. We are also working on the header and I have a new modular version on the drawing board that may, or may not, see the 'light' of day. I intentionally go out and race the snot out of my NCs in a way that few do, with the intention of breaking stuff repeatedly so I can find stuff that needs improvement...and breaking stuff is FUN with the right attitude.
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Re: P0421 CEL

Postby jboemler » Sat May 21, 2011 4:31 pm

Modular header? <ears perked> Is this with the idea of an easier install, or what?
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Re: P0421 CEL

Postby Brian » Sat May 21, 2011 4:56 pm

jboemler wrote:Modular header? <ears perked> Is this with the idea of an easier install, or what?


Hi Jim,

The idea is you get two headers in one design. Think of a shortie header that uses the converter as a bolt in collector in the stock location...but you can swap out that converter with a bolt in straight pipe. Prototype is 1.5 inch primaries (smaller than our RoadsterSport header, but same as PPE and Racing Beat). You get a track header without converter, but you can put the converter in for classes that require it in stock position (like current STR rules), or for street use and your emissions testing, etc. And perhaps we really get crazy and make it three headers in one.....with flange design that allows customer to later put a turbo in gap. Again, not sure if product results from this but playing around with it to see how practical and efficient we can make it.
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