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Thread: P0421 code

  1. #81
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    Quote Originally Posted by littlemoule View Post
    Actually I need something, I am looking at Universal fit Magnaflow Cat Converter - what should be the inlet and outlet diameter size of the pipe for easiest fit?
    Again I question: 1) Does the car otherwise run good? 2) Do you have to do emissions testing or inspection where you live? 3) Can you just ignore it?

    I've not been faced with having to replace a catalyst thank goodness. But off hand, if I were in your shoes, I think I would look for one about the same size as the stock one. It has to scrub it enough to come out with no oxygen in the exhaust. I don't know the pipe size. And there's one other thing about catalysts that I'm not skooled on. Seems like there's different "types." I think the latest type of catalyst is called a 3-way maybe. I'm assuming all modern cars are running 3-way catalysts ... but I don't know that. You'd have to get the same type.

    But again, if I had no inspections to pass, and the car was driving good and returning good mpg, I'd find a way to put it out of my mind and drive it. At least for a good long time, or until drivability and/or mpg suffers.


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        click to view fuel log View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)


  2. #82
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    Alright so to answer the question:
    I check the fuel avg consumption. It just shot up from avg 6.6 L/100 to 11.2 L/100
    So I think I should get a new cat converter. Can anyone point me to a MagnaFlow Universal Catalytic Converter that will be the close fit with a little bit of welding?
    I found MagnaFlow converter to be of good value. Direct aftermarket converter are well over $700 CAD. So I will stick to magnaflow.

  3. #83
    You didn't really answer the question of "does it run good?"...

    My average economy on the cluster looks crappy too if it idles too long and first thing in the morning when it's not up to temp.

    21mpg? That's unbelievable. How about those spark plugs?
    6.6(35mpg) is pretty crappy too, especially for a 5 speed.

    If the cat was plugged it'd be almost un-drivably slow. I haven't seen one plug(on these cars) but anything is possible...

    I assume you've already done the obvious and check the air filter and make sure nobody is living in the airbox?
    Last edited by Fummins; 05-31-2023 at 08:13 PM.
    Mirage videos:

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        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


  4. #84
    Quote Originally Posted by 7milesout View Post
    Again I question: 1) Does the car otherwise run good? 2) Do you have to do emissions testing or inspection where you live? 3) Can you just ignore it?

    I've not been faced with having to replace a catalyst thank goodness. But off hand, if I were in your shoes, I think I would look for one about the same size as the stock one. It has to scrub it enough to come out with no oxygen in the exhaust. I don't know the pipe size. And there's one other thing about catalysts that I'm not skooled on. Seems like there's different "types." I think the latest type of catalyst is called a 3-way maybe. I'm assuming all modern cars are running 3-way catalysts ... but I don't know that. You'd have to get the same type.

    But again, if I had no inspections to pass, and the car was driving good and returning good mpg, I'd find a way to put it out of my mind and drive it. At least for a good long time, or until drivability and/or mpg suffers.
    1: who knows...
    2: Doubtful
    3: small piece of electrical tape over the light works great
    Mirage videos:

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


  5. #85
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    Quote Originally Posted by Fummins View Post
    21mpg? That's unbelievable. How about those spark plugs?
    6.6(35mpg) is pretty crappy too, especially for a 5 speed.
    I was going to let it go. I went and did the math and saw 21 mpg too. I have to believe that if it is actually achieving that as a daily driver, it must be a real dog for acceleration. If the mpg is true, I have to believe that cat is plugging. And that would constitute (in my mind), no, it is not driving good. But "who knows" is the case for all but littlemoule.

    However, I can understand if littlemoule has nothing to compare their Mirage driving experience with and can't make a decent judgement as to how it is driving.

        __________________________________________

        click to view fuel log View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)


  6. #86
    Quote Originally Posted by 7milesout View Post
    I was going to let it go. I went and did the math and saw 21 mpg too. I have to believe that if it is actually achieving that as a daily driver, it must be a real dog for acceleration. If the mpg is true, I have to believe that cat is plugging. And that would constitute (in my mind), no, it is not driving good. But "who knows" is the case for all but littlemoule.

    However, I can understand if littlemoule has nothing to compare their Mirage driving experience with and can't make a decent judgement as to how it is driving.
    Yeah, if you've only ever felt 50 of the 74 neck snapping horse power then look out!
    I'm pretty sure I managed 30ish mpg on the trip I took the other week. That's loaded with about 900-1200lbs worth of crap in it, probably 6hrs of idling, just all around worst case scenario except the weather was pretty good for 3/4 days.
    My turd still has the factory cat at 312,000km/193k miles. I often see them start to throw efficiency codes around 300k km. Maybe beating the snot out of it there just cleaned it out and bought me some more time lol They clean diesel particulate filters by putting them in some overpowered oven, so it's basically the same thing...
    Mirage videos:

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


  7. #87
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    Quote Originally Posted by 7milesout View Post
    I was going to let it go. I went and did the math and saw 21 mpg too. I have to believe that if it is actually achieving that as a daily driver, it must be a real dog for acceleration. If the mpg is true, I have to believe that cat is plugging. And that would constitute (in my mind), no, it is not driving good. But "who knows" is the case for all but littlemoule.

    However, I can understand if littlemoule has nothing to compare their Mirage driving experience with and can't make a decent judgement as to how it is driving.
    Honestly it does feel it's running a bit choked. Although I don't have a reference that's correct but from 10kmh to 30kmh in between Second Gear, I do have to nearly floor the gas pedal to pick up momentum. Since we have ruled out the O2 sensor, it really can only be the cat. I just want help to pick a universal magnaflow converter that will fit with the least amount of modification. I do know of a good welder who can do it but I don't want to buy a converter that won't fit the O2 sensors etc without heavy modification. A standard EPA converter will do, doesn't have to be CARB compliant.
    Car isn't running too good.

  8. #88
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    littlemoule - The best advice on choosing a cat is going to come from Fummins. Because a) he knows tons and has probably dealt with cats within his Mirage fleet, and b) he's Canadian. Us southerners don't know the Canadian market so well. But I'm going to take a look in a few minutes and take a stab at it because you never know, I may find myself in this position and a little knowledge couldn't hurt.

    One other suggestion before I go poking around at cats. Might you find someone locally with a Mirage while you're in your Mirage and run them down and see if you can explain your way into letting you take theirs for a quick spin. Might not take more than a half mile to feel a difference. If they see you in a Mirage, they'll likely relate to you and let you do it. THAT will diagnose your driving condition better than anything else, except to take it to a drag strip maybe. Driving someone else's car is free though!

        __________________________________________

        click to view fuel log View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)


  9. #89
    I've replaced one or 2. I just stuffed a used one from a wreck. There are a few cars that keep throwing cat efficiency codes. They still drive fine except for one with over 500k km is a little sluggish.
    I see a lot of magnaflow cats get sold but I've never installed one. If/when I see a cat code in my personal car, I'll either gut it or chop it out and weld in a piece of pipe in it's place. If I didn't want it to stay quiet I'd consider doing it anyways, but that won't solve the cel. I still may experiment with that one year? I still have a hard time with the cat being plugged at under 300k kms unless it's burning oil badly or something is living in it.
    Mirage videos:

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


  10. #90
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    I studied a bit. So, we have 2 cats. But my assumption is that the first cat takes all the beating and is probably 90% likely to be the one with the issue. If it were me, I would consider buying the $371 cat from rock auto. It comes complete to the manifold. However, I'm not really trusting that manifold, I'd have to eyeball the stock manifold to see how similar it is to the one pictured on rockauto.

    If I lived in a location that did not do emissions testing, I would simply pull the stock manifold and bad catalyst off, and replace it with one of the "performance" headers that have been discussed in these forums. Not for the "performance" aspect of it, but as a way to eliminate the catalyst. In littlemoule's case, if that catalyst is plugging, and he put a header on it with no cat (but a bung for 02 sensors), I think he would see rather large performance gains.

    The downside is, I think he'd be getting cat efficiency codes. Which I could live with if I KNEW that the codes were simply telling me that the catalyst that I DON'T HAVE is not working effectively ... and if the car was running good.

    littlemoule - A lot of the Magnaflow cats I saw looked like the 2nd cat in our system. So, you'd have to be sure you're getting the correct cat for fitment reasons. The Magnaflow stuff looked like decent or better quality though. The first cat (on the 2020 which is what I looked at) appears to bolt into place. No need for welding. But gonna need good impact tools to remove those bolts.


        __________________________________________

        click to view fuel log View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)


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