Reason's Why...
 

I have gone through 4 catalytic converters in a year? 2 warm-up cats and 2 mid-pipe cats.

Stock 1999 miata, 5speed.

Cheap cats (first 2 were oem)? Engine running rich (but temp gauge reads normal)? Somebody out to get me?

If the engine's running rich you can blow cats. Figure out why you're rich.

My car is covering up for me being poor... Any likely causes I should check into first?

o2 sensors, and coolant sensor would be my first check. I've never owned a stock miata so I'm not an authority on what typically goes wrong, just speaking from general car knowledge. I'll let someone else go in depth.

I wasn't aware that apostrophes showed plurals.

Find out why you're rich, running rich will fuck cats. Solution? Buy an MS :)

Live in a state that doesn't have emissions testing.

It doesn't. I was only talking about 1 engine. Get it: "If THE." Granted my usage in that case was incorrect, but, 's in addition to showing ownership can also imply "is" such as in the word "it's" which actually means, "it is"

As I said, it was a bastardization on my part, but try and keep up. And holy shit, really? On my nuts for apostrophe usage on a car forum? i wUd UnDeRsTanD iF i tAlK'd LiEk tHiZ, but seriously, I use capitalization and punctuation and you get me on a misplaced apostrophe? At least get my intended usage right. Context son!

/rant

Any rough running? 99s have been known to blow the coils and start dumping fuel into the cat.

--Ian

In cold start engine idling in high rpms and it's very rich.If you try to warm your car static it will harm your cat.

I would look at ignition problems first.
Misfires, worn insulation on plug wires, etc..

When you're on a site, any site, that requires the use of communication, specifically through the wirtten word, it is courteous to have some sort of respect for language arts.

To maunder around in such a opprobriuos manner opens you up for raillery.

Maunder?:hustler:

opprobriuos?:hustler:


Someone's been reading the dictionary

No, my car hasn't been running rough, misfiring or showing any other signs I've noticed. It hasn't thrown any engine codes except for the ones related to failing catalytic converters, but I'm aware running rich could damage the cats, I just wish there was some other sign before I have to spend $99 on an engine diagnostic with my repair shop.

ms?

maunder /MON�dur/
v. to talk incoherently; to ramble

opprobrium /uh�PRO�bree�um/
n. disgrace, infamy, or reproach; the cause of shame or infamy

raillery /RAY·luh·ree/
n. good-humored banter or teasing

codrus has it right, weak ignition coils in the 99's are a very common problem. I picked up my car really cheap because it would barely move under it's own power. I told the dealer I'd buy it if they'd let me work on it in the back for an hour. Jacked the thing up, busted the cat out, drove it home and replaced the coils.

Post in the WTB section, enough of us that have converted to coil on plugs that there should be plenty of extra stock 99 coilpacks laying around that someone is willing to sell you.

The funniest part of you over-reacting is that I'm pretty sure he was referring to the misused apostrophe in the OP's thread title, and not the "engine's" in your post.

Way to freak out, though.

Reason is why.

I wasn't going to say anything...

Was talking to OP ;)

Where have you been getting replacement cats from?

My first cat on my 99 has been shot since I bought the car 75,000 miles and 7 years ago.

I'm looking forward to pulling it off the car to replace it with a turbo manifold.

Internet, I believe they were both magnaflow, but I cant find the receipt for this warmup cat. I'd like to go ahead and replace my exhaust from the downpipe and back with a turbo setup in preparation for the turbo...

how do you know there cats are dead?

Hah, okay, long story?

First, the rear cat imploded on itself. Literally, it broke apart, then plugged my exhaust because it wasnt flowing properly. So it overheated, threw a code, and eventually melted itself closed thus killing my engine. Now, the warm-up cat threw a code, p0421, in addition to a MAF code, p0102.

Note, I replaced both cats just under a year ago for nearly the same codes. The rear cat I replaced accidentally, thinking it was bad when it was really the warm-up that needed replacing.

It's always the warm up cat on 99's, isn't it? I mean... Mazda changed that setup in 2001 for a reason. I feel like we're the guinea pigs that got screwed. Should have been a recall.

How frequently do you have to get tested? Why not just run a test pipe?

I'm just going to replace the whole exhaust with a turbo setup. Also, replace the coils.

Another thing I didn't mention was my gas mileage has never touched 30mpg. Which I know I should be able to, however, it hasn't happened.

Emissions testing every 2 years, but it just has to pass OBD2. However, if they smell that exhaust without that cat, they might know something is up.

Yup. Out here in smog land, the cops will smell the exhaust and you get an invitation to go see the state referee. Better have all your ducks in a row when that time comes.

Lmao, FAIL. I even checked over all the posts as I was confused WTF he was talking about. Never thought to check the title. Mine was the only apostrophe I could find. :facepalm:

But who's freaking out? Of course I over-reacted, it's the effing internet. I'm also a pro cage fighter that fucks Rihanna and Shakira after bouts while piping missle's up the Soviet Union's ass (it still exists) from the seat of my F-35.

Dude, you're a bad ass!

that's a pretty subjective test. lol. I'd load my muffler up with crabs and cheese.

Subjective? You know the difference when you smell it, right?

Crabs and cheese... hahaha

I should add that it was one guy I know that the cop did that. I'm not sure if they're all running around smelling exhaust or not.

That's why you shut off your car when the cop pulls you over. If he smells it on the road you better just run.

Anybody have any other ideas as to what is killing my cats?

Yup, that's how I always did it. Turn that motor off immediately, and try to wait for them to leave before restarting the car.

We also have mobile sniffers out here that get setup on freeway on-ramps and stuff. They use infrared or something to sense smog coming from gross polluters. They then snap a pic of your license plate, and you get an invitation to a smog check in the mail. :vash:

Sorry for off topic... I just find this stuff funny when compared to other states. The money wasted on smog checking little cars while the big trucks just keep dumping pollution kills me.

Is your ECU modified in any way, or is your tune still bone stock?

When you put on the new cats, the codes went away for a while?

How's your gas mileage?

My gas mileage hovers at 28 highway, it should be higher, I'm pretty sure. Other than the cats, the car is entirely stock right now.

Because it was free...

http://www.allfunnypictures.com/images/freecat.jpg

Mine gets 28 highway, and always has. Of course that first cat has always been bad.

:/ I've known a stock miata that did better than 30 mpg...but maybe she drove a bit slower...

I'm really hesitant to modify this car if I cant figure this out...

Ditch the stupid pre-cat system...and give California the middle finger for it. Get a 01-05 exhaust manifold for now. You only need a main converter under the car. Swap out the ECU for a Federal one while you're at it.

I plan on ditching it and getting a nice turbo-ready ecu. Til then, I want to make sure my engine isn't doing all this damage of its own accord.

I've been told to stop it from throwing a code, you just need to move the second O2 sensor further back behind the main cat. It doesn't see a change across the pre-cat, so it throws the code.

But I agree that ditching it completely is the way to go. It's not needed to pass a sniffer test once the car is warmed up. (at least every two years when I get mine through, it passes no problem)

I'm not sure it's worth my effort to swap it until I get a turbo on the car.