NC2 issues after running basic tune

Tuning discussion specific to 2009-2015 NC2 and NC3 Miata MX-5 vehicles
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Moke
Posts: 3
Joined: July 9th, 2020, 2:27 pm

NC2 issues after running basic tune

Post by Moke »

I recently installed the basic tune w/ crackle and pop ( I had to see what it sounded like). Ran to North Carolina to run the Dragon. Ran great, all was well. Before I headed home I reinstalled the baffles in my Roadster Sport Super Q exhaust. Drove about 50 miles and my check engine light came on. It ran a little rough at first but then smoothed out for the rest of the trip back home (about 500 miles). Code turned out to be a P0421. Points toward 02 sensor or perhaps cat. Cleared code and reflashed to get rid of the crackle and pop. Pulled out the baffles. Car still runs good but exhaust seems really quiet.
I am not familiar with the crackle business. I understand it runs rich and burns late to make the noise? Could this have plugged my cat?
Coincidence?
Any help here is appreciated.

mituc
VersaTuner guru
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Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: NC2 issues after running basic tune

Post by mituc »

The excess of fuel is minimal for the crackle part of the tune. I don't think this damaged your cat but it's still possible especially if the cat was at the end of its life (they usually last quite long though).

Flash a base map without the crackles and see how it goes after a while.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071, ~476WHP @31-32PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 320-ish BHP

Moke
Posts: 3
Joined: July 9th, 2020, 2:27 pm

Re: NC2 issues after running basic tune

Post by Moke »

Flashed the base map without the crackles and thats when the exhaust seemed to get quiet. It threw a code again today. I havent looked yet but will assume another p0421 till I get back outside.

nc2pvn
Posts: 3
Joined: July 12th, 2020, 8:35 pm

Re: NC2 issues after running basic tune

Post by nc2pvn »

Have the exact same issue. installed pops and crackles tune and drove it for about 100 miles. then code p0421 came up and now can’t hear the pops anymore. also the exhaust got much quieter even thought it has a muffler delete. performance seems to be affected too. wandering what i should do now. don’t want to cause damage to the engine by driving it as is.

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Steve @ VersaTune
Lead tuner
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Joined: March 29th, 2010, 12:58 pm

Re: NC2 issues after running basic tune

Post by Steve @ VersaTune »

It's possible that the primary cat was loose already and the pops knocked pieces into the secondary cat. I've only heard of a couple instances of this happening. I put thousands of miles on a cack and pop tune on my MS3 before we released the cracks and pops tunes. I had no issues.

nc2pvn
Posts: 3
Joined: July 12th, 2020, 8:35 pm

Re: NC2 issues after running basic tune

Post by nc2pvn »

That’s weird because the car has only 43k miles. Would you suggest removing both cats or just the primary cat

Moke
Posts: 3
Joined: July 9th, 2020, 2:27 pm

Re: NC2 issues after running basic tune

Post by Moke »

Been out of town and now back into this. I was kind of thinking it was close to going bad and the tune put it over the edge (or perhaps the hard driving of The Tail of the Dragon :) ). I replaced a O2 sensor with no change. Thinking Ill go ahead and just order the cat (or header and midpipes) . If I just disable the P0421 code will it show up when trying to get it inspected? Missouri allows 1 or 2 monitors to be incomplete when testing. I want it right but it would be great to get it to pass this week. i cant get the cats in and installed before it expires.

mituc
VersaTuner guru
Posts: 970
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: NC2 issues after running basic tune

Post by mituc »

Usually the secondary O2 sensor is responsible for this code, I hope you replaced that one.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071, ~476WHP @31-32PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 320-ish BHP

nc2pvn
Posts: 3
Joined: July 12th, 2020, 8:35 pm

Re: NC2 issues after running basic tune

Post by nc2pvn »

Took off my headers and saw that the cat has broke into several pieces. removed all the debris and what was left of the cat and now the car drives normal. however now i have check engine light for code p0421. is there a way to disable this code with versatuner?

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