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Discussion Starter · #1 ·
I'm having some problems with the codes:

P0421- Warm-up catalyst system (RH) efficiency below threshold ON 2 Catalyst

P0302-P0306- Misfire detected.

The P0421 I have no idea what would cause that, I've read; faulty cat, faulty O2's, but is there any way to check which one?

For the misfires, I get various cylinders "misfiring" (I don't really think it is), and it only happens when I really push the car. I know if you push it too hard when its cold it will throw the dummy code, but the car is completely warmed up. Perhaps something to do with the plugs? (I just changed them 10k ago).

I'm almost thinking about getting my car reflashed with the latest update (Its an '03 and I don't know when the last update was performed, at least before May '05), but am out of warranty so I'm not sure on how much it would cost to have it done. Does anyone know?
 

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I'm having some problems with the codes:

P0421- Warm-up catalyst system (RH) efficiency below threshold ON 2 Catalyst

P0302-P0306- Misfire detected.

The P0421 I have no idea what would cause that, I've read; faulty cat, faulty O2's, but is there any way to check which one?

For the misfires, I get various cylinders "misfiring" (I don't really think it is), and it only happens when I really push the car. I know if you push it too hard when its cold it will throw the dummy code, but the car is completely warmed up. Perhaps something to do with the plugs? (I just changed them 10k ago).

I'm almost thinking about getting my car reflashed with the latest update (Its an '03 and I don't know when the last update was performed, at least before May '05), but am out of warranty so I'm not sure on how much it would cost to have it done. Does anyone know?
[/b]

Just specuations here:
I get the 0421 code, but I have headers and a Hi-flow cat, so I figure the car is confused that it breathes so well.

I got a 0300 code too, but I was really low on gas the day before. Perhaps the air to fuel ratio was thrown off, as there wasn't much fuel and the CP-E intake brings in alot of air...
 

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Discussion Starter · #3 ·
I never even thought about the low gas thing. I think everytime I've had it come up is when I'm low on gas and push the car past 5.5-6k. I'll try keeping it above a quarter of a tank when I push it from now on and see what happens with it. Thanks.

As for the P0421, I just realized there is a lot of black soot on the tail pipes. Would this be indicative of a bad cat, or a fouled O2 sensor?
 

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Mike, I don't think a reflash would hurt. I needed a reflash to rid mine of a recurring "Very small emmissions leak" CEL. I can't imagine that a reflash would be expensive, takes a couple minutes max. I'd call up Mazda Direct and ask them, they're pretty good there, or of course call Park if you felt like taking a drive. If you go with the latter, let us know and we'll meet up somewhere.

I'd start with the reflash though for sure. You've never had one?
 

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Discussion Starter · #5 ·
Mike, I don't think a reflash would hurt. I needed a reflash to rid mine of a recurring "Very small emmissions leak" CEL. I can't imagine that a reflash would be expensive, takes a couple minutes max. I'd call up Mazda Direct and ask them, they're pretty good there, or of course call Park if you felt like taking a drive. If you go with the latter, let us know and we'll meet up somewhere.

I'd start with the reflash though for sure. You've never had one?
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Nope, never had one since I've owned the car. I'll give that a shot, and see what I can get. The car is acting really funky now. Very erratic idle, stalling constantly, and a weird knock when I accelerate. I'm up in Ashland right now to see my girlfriend(I saw you on 71 yesterday at around 2pm btw), so I'm going to bump up the octane a bit to see if that helps the knock at all, and when (and if) I get home I'll probably take everything back to stock until summer comes when I have time to take care of it.
 

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Oh yeah? That was me, on my way down to C-bus to watch the Bluejackets play last night. Fucking game went to a 12-round shootout, and the Jackets won it. Amazing, plus that area of town is great.
 

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Oh yeah? That was me, on my way down to C-bus to watch the Bluejackets play last night. Fucking game went to a 12-round shootout, and the Jackets won it. Amazing, plus that area of town is great.
[/b]
And I didn't get a call? :huh: :sarc: :D j/k, I saw the highlights on ESPN this morning, looked like a hell of a game.
 

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Discussion Starter · #8 ·
Ok, somewhat of an update:

Today, I checked my oil level and filled it up by half of a quart to the max fill line. I put in chevron with techron, and drove the 100 miles back home with no issues besides the ticking (stalling issue is gone). I get home, and have my dad listen to it, and narrows it down to coming from the intake manifold. The car also reeks of fuel when running, but there is no CEL displayed for running too rich. So I'm at a loss as to what this could be.

Is there a butterfly valve in the manifold that acts the way the stock airbox does? Could the ticking noise be that valve not operating properly, and would this cause a change in my a/f ratio with no CEL being thrown because its after the MAF? Would this also explain an "inefficient cat" CEL to be thrown, and has this likely fouled my O2 sensor?
 

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I'm having some problems with the codes:

P0421- Warm-up catalyst system (RH) efficiency below threshold ON 2 Catalyst

P0302-P0306- Misfire detected.

The P0421 I have no idea what would cause that, I've read; faulty cat, faulty O2's, but is there any way to check which one?

For the misfires, I get various cylinders "misfiring" (I don't really think it is), and it only happens when I really push the car. I know if you push it too hard when its cold it will throw the dummy code, but the car is completely warmed up. Perhaps something to do with the plugs? (I just changed them 10k ago).

I'm almost thinking about getting my car reflashed with the latest update (Its an '03 and I don't know when the last update was performed, at least before May '05), but am out of warranty so I'm not sure on how much it would cost to have it done. Does anyone know? [/b]
The two codes do sorta relate. If the motor is having a misfire issue it will cause the mixture to be excessively rich which the cat may not be able to correct and thats what the catalyst efficency code is all about. You comment that the motor smells of running excessively rich could be caused by a misfire problem. those would cause the catalyst code.
 

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That misfire code happens to alot of 6's when they are pushed hard. It is supposed to be an error, and probably a new flash would fix it. As far as the cats you might have a bad cat, or a bad sensor. Get the sensor tested and go from there.
 

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Discussion Starter · #11 ·
Well after reading this: http://www.obd-codes.com/trouble_codes/gen...re-detected.php

Coupled with my P0421 code, a faulty O2 sensor does seem to the be the most logical cause of the problem, thanks to DennisW for pointing me in the right direction with this. So what the site says for symptoms of a misfire are:

Symptoms may include:
* the engine may be harder to start
* the engine may stumble / stumble, and/or hesitate
* other symptoms may also be present
[/b]
I have a hard time starting my car, and the idle is erratic. For causes it says:
* Faulty spark plugs or wires
* Faulty coil (pack)
* Faulty oxygen sensor(s)
* Faulty fuel injector(s)
* Burned exhaust valve
* Faulty catalytic converter(s)
* Stuck/blocked EGR valve / passages
* Faulty camshaft position sensor
* Defective computer
[/b]
I just changed my plugs 10k miles ago, so I don't think its that. However, the others are all possibilities I suppose, would any of these cause a weird ticking/clicking noise at idle and during acceleration?

Also, what is the best way to test the O2 sensor, check for a change in voltage between the one pre-cat and after the cat?
 

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yeah, throw a multimeter on them and see if the voltages are responding. if your not having a specific o2 sensor code however, its probably fine...


make sure all the wires connecting your plugs and all are tight, and tighten up the ecu harness.

i might even suggest pulling the plugs to see which cyl's are fouled.
 

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Discussion Starter · #13 ·
yeah, throw a multimeter on them and see if the voltages are responding. if your not having a specific o2 sensor code however, its probably fine...
make sure all the wires connecting your plugs and all are tight, and tighten up the ecu harness.

i might even suggest pulling the plugs to see which cyl's are fouled.
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Will do. I'm probably just going to go through the whole intake portion of the engine up until the spark plugs to look for faults. I'm almost wanting to put it back to stock and sell it, its just too much of a money pit for me after all the mods, and the clutch change at 63k really sealed the deal on it. :tear: Good news is that might mean some quality mods for sale...just need to find out what kind of car I want.
 

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Almost all the cars tick... Actually alot of modern cars tick. Everyone fights over why... But they do.

You can not count mods as a money pit. Only repairs.
 

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Discussion Starter · #15 ·
Almost all the cars tick... Actually alot of modern cars tick. Everyone fights over why... But they do.

You can not count mods as a money pit. Only repairs.
[/b]
But the tick is noticeably louder than normal. Like it had a faint tick to it, but now its just obnoxiously loud, and when idling it feels/sounds like the car is going to blow up. But when driving it drives normal (no timing being pulled), just the ticking during acceleration and idle at a stop sign/light.
 

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Discussion Starter · #16 ·
Anyone think the crankshaft position sensor, or knock sensor could be to blame for this? I've had both codes come up in the past, but never caused any problems. Just let the car sit and it was fine.
 

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Discussion Starter · #17 ·
Ok, finally I have actually evidence as to what is going on now that I'm back from school for the weekend. I have a pending code: P0138- O2 Sensor Circuit High Voltage (Bank 1 Sensor 2).

The noise that I previously described as a tick, is now a rattle, and I have tons of smoke pouring out of my exhaust. The car idles 100% smooth, but sounds like a tractor and the engine has a lot of vibration in it. (I've never been around to hear or see a bad cat, but does this seem like it?) I have a screenshot of the onboard testing autoenginuity does:


And a .xml file of my logging is attached (opens in internet explorer): https://carmen.osu.edu/pages/personal/93513/o2voltage.xml (right click save as please!)

Is this just a bad cat? I believe by the EPA law I'm supposed to be covered up to 80,000 or 120,000 miles under warranty on OEM catalytic converters, right?

Edit: Just took it for a drive. There is a brutally obvious loss of power, and it smelled like something was burning when I got in the garage. I opened the hood and the front cat was glowing red. Whats going on? Perhaps the cat is in pieces in my exhaust blocking flow which in turn equals power loss??? I've also seen this could be symptoms of a bad coil. Any takes any of this?
 

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Discussion Starter · #18 ·
Anybody???, I'm only home for the weekend so I really want to get a head start on this problem if at all possible.
 

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Discussion Starter · #20 ·
Mike I think that's a bad cat for sure. It's probably clogged like hell, same thing happened on my Dodge Ram.
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Sweet, now just to take it to the dealer to try to get it covered under that EPA law, now to just find the root of the cat going bad.
 
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