P0421 code

[Fummins]

I'll check back at page 30.

[littlemoule]

Okay so I can provide some updates. Yes I replaced the spark plugs already, with these ones to be exact:
NGK 96355 Ruthenium HX High Ignitability; Pre-Set Gap: 0.044"
I also want to mention that for last several days, the CEL has not come ON.
I have not thrown any parts yet on the car, except purchased the catalytic converter (and it is still under return period).
I will know some answers by Friday, taking it to a different shop to get some assessment done on how easy/hard it will be to install the magnaflow universal cat converter and if it will keep the computer happy or not. Regarding the fuel mileage, I am going by the trip meter, but for next 2 days, I will fill to the top, drive and then refill to get a more accurate mileage measure.
Will get to the bottom of this.

[littlemoule]

I'll check back at page 30.

Might get resolved by 29 lol

[Fummins]

Okay so I can provide some updates. Yes I replaced the spark plugs already, with these ones to be exact:
NGK 96355 Ruthenium HX High Ignitability; Pre-Set Gap: 0.044"
I also want to mention that for last several days, the CEL has not come ON.
I have not thrown any parts yet on the car, except purchased the catalytic converter (and it is still under return period).
I will know some answers by Friday, taking it to a different shop to get some assessment done on how easy/hard it will be to install the magnaflow universal cat converter and if it will keep the computer happy or not. Regarding the fuel mileage, I am going by the trip meter, but for next 2 days, I will fill to the top, drive and then refill to get a more accurate mileage measure.
Will get to the bottom of this.

Time will tell. It can take a while before the codes come back. I drove mine 2 days around 500kms before a light came on because I disconnected the charcoal canister. I cleared it 2 days ago and it still hasn't come back on. The code is there but it's not turning the cel on.

Hopefully plugs were your fix. I haven't tried Ruthenium plugs, I just replace with the same oem style ngk iridium.

[klroger]

taking it to a different shop to get some assessment done on how easy/hard it will be to install the magnaflow universal cat converter and if it will keep the computer happy or not.

It may be interesting to see how this will work, as the link you posted earlier states it's for a "pre OBDII" systems. I don't know what the difference is tho, so you may be OK...
(complying with legal standards for pre-OBDII Federally registered vehicles.)
Just thoughts...

[Fummins]

LOL. This makes no sense. A sensor cannot destroy anything other than itself.

I wish I noticed this post earlier. That's a funny way of saying thanks for the advice. Good luck with your car.

[littlemoule]

It may be interesting to see how this will work, as the link you posted earlier states it's for a "pre OBDII" systems. I don't know what the difference is tho, so you may be OK...
(complying with legal standards for pre-OBDII Federally registered vehicles.)
Just thoughts...

This is an excellent catch. Actually I sent that one back and ordered this one instead.
https://www.magnaflow.com/products/5...onverter-54306
Stay tuned, will report back with pictures and new assessment.

[7milesout]

It looks too long and skinny to fit where the first cat goes. I don't know, but I think you'd need one more fat n stubby.

[littlemoule]

We haven't tackled the challenge yet but here are the pictures of stock.

[littlemoule]

We haven't tackled the challenge yet but here are the pictures of stock.

One more thing that I think Mitz is missing is this:
https://mirageforum.com/forum/showth...158#post152158

My very first Post, I drove the car like that for 1 month before I finally found that thread and fixed the wires. Could have killed the cat in the process. So it's not just Krown it's two things 1) Misfire Run for 1 month AND 2) Krown. The timing could have been purely coincidental but that's what I am trying to figure out in this thread. It's either one of the two, CAT or O2, I am leaning more towards CAT and not the O2 and the reason for that is Mohammad's post, if Krown completely clogged the O2, the computer would trigger a different code not catalytic converter WARM UP efficiency code. This let me to believe that catalytic converter got damaged in the process due to misfire runs and Krown became a placebo cause. As for the links provided, I am not sold on them because their problem is not the same as mine. Critical thinking is required here.