P0420 and P0106 - related?

[Walsted]

My mileage went from around 29.6 to 27.7 for two tanks, so I pulled codes. Got P0106 and P0420. Did a pointy search on P0106, cleaned out the place on the intake where the vacuum line for the MAP sensor connects, and cleaned the electrical connectors on the valve underneath the MAP sensor. Cleared codes, but haven't driven enough for them to come back.

The cat has a little over 11 months and 22K miles on it. Is it likely that the P0420 was set by an improper fuel mix due to bad data from the MAP, or is it more likely that I need to get a new one (again)? The last one was installed by a shop on Hemphill, so it probably wasn't the highest quality piece on the market, but I was hoping for at least a couple of years out of it.

Thanks.

[gabkwong]

My mileage went from around 29.6 to 27.7 for two tanks...

Wow, I would be very happy if I get 27.7! Of the 9 years I have my NB, the best I ever (mostly freeway driving) was 27.

[johnwag]

Check your O2 sensors. http://www.obd-codes.com/p0420

I've only had M1 miatas, and I'm starting to learn NB's. Where is the map sensor located on an NB?

[Walsted]

Check your O2 sensors. http://www.obd-codes.com/p0420

I've only had M1 miatas, and I'm starting to learn NB's. Where is the map sensor located on an NB?

If the P0420 doesn't stay cleared, that is the next step, and then the step after that would be getting a new cat. I'm hoping it stays cleared, though.

The MAP sensor on my NB is passenger side, along the fender about halfway back.

[POS Racing]

Wow, I would be very happy if I get 27.7! Of the 9 years I have my NB, the best I ever (mostly freeway driving) was 27.

+1

I'd be even happier if our '02 that serves as daily driver would even get in the mid 20 MPG range!

Walsted did your car kick a CEL or were those just codes it had stored?

[Walsted]

+1

I'd be even happier if our '02 that serves as daily driver would even get in the mid 20 MPG range!

Walsted did your car kick a CEL or were those just codes it had stored?

Those were stored codes. I wouldn't have noticed any problems if I didn't track gas mileage and scan for codes when I noticed an unexplained decline.

[POS Racing]

Those were stored codes. I wouldn't have noticed any problems if I didn't track gas mileage and scan for codes when I noticed an unexplained decline.

Is the cars normal route consistent enough to be able equate for that massive 1.9 MPG difference??

[Walsted]

Is the cars normal route consistent enough to be able equate for that massive 1.9 MPG difference??

Yes, my life is that boring.

[POS Racing]

Yes, my life is that boring.

Bummer....

[Walsted]

After further testing, I have confirmed that the P0106 and P0420 are independent, the P0106 has been cleared/repaired, my O2 sensors are working, and my cat is dead.

Does anyone know of a place that has a decent cat (installed) for a decent price? As in just cut out the old, dead one and weld in a new that will hopefully last more than a year and let me pass the smog test.

Thanks.

[POS Racing]

Correct me if I am wrong: If you car is not kicking a CEL won't it pass inspection as it sits?

Also no warranty on the 11 month old replacement??

The cat has a little over 11 months and 22K miles on it.

[Walsted]

Correct me if I am wrong: If you car is not kicking a CEL won't it pass inspection as it sits?

Also no warranty on the 11 month old replacement??

Since it stores the P0420, that code will come up when it is connected to the smog station test equipment. I don't know why it isn't triggering the CEL.

The place I got the last cat was one of those hole-in-the-wall places on Hemphill. They don't warranty converters, or maybe only warrateed to 90 days, or something similar.

[POS Racing]

Before I would throw yet another on it I'd want to figure out why it smoked one in less than a year, unless you like buying a every year.

But that's just me!

Ya got one of these deals yet? Looks like it could help ya pinpoint the problem - http://www.scangauge.com/

[Walsted]

I've got the Harbor Freight CAN/OBDII code reader. I figured this one may have died due to the bad MAP readings giving a bad fuel/air mix, and it being a pretty cheap cat to begin with, but don't know if that is it for sure.

[POS Racing]

The Scangauge will give ya the ability to measure the O2 sensors on an NB - http://forum.miata.net/vb/showthread...=scangauge+cat

Have you checked the O2 sensors? How many miles on your scooter?

Unless your Hemphill special was junk I still have trouble getting my head around a 11 month lifespan on a .

[POS Racing]

I think trickyrix is our latest buyer, he should know of a TCB source for a !

[Walsted]

I checked the O2 sensors with a voltmeter. The rear and front voltages matched, (varying from .2 to .7,) so I figure that there are no changes in O2 levels occurring between the sensors, hence the cat isn't doing anything.

[sammm]

trouble getting my head around a 11 month lifespan on a .

Unless the coil pack is bad/going bad. That will fry a cat in no time.

[jrj512]

I think trickyrix is our latest buyer, he should know of a TCB source for a !

I'm no trickyrix, but I just bought a cat from Flying Miata (or was it Moss?) about three weeks ago. Since I recently decided to move to STS2 next season where I can use a high-flow cat, I would be willing to sell my almost brand new OEM-style cat. It is on a '93. Does anyone know if they are the same for '93 and '99? If so, Walsted, feel free to PM me about a possible deal.

[Walsted]

jrj512 -
Since mine has been replaced in the past by a universal cat, the OEM style won't bolt right up.

According to the Magnaflow web site, I need a Magnaflow 99204HM. (just ordered one.) I think my curent cat is a Catco. Catcos didn't have a real good reputation among the smog testers in California, but I usually got a few years out of them.

Thanks.