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Old 06-08-2016, 08:39 AM   #1
AlaxyGalaxy
 
Drives: 2004 Echo HB 5-door
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Aftermaket exhaust, PO420 code?

I swapped my Toyota midpipe (2004 Echo HB) for a used aftermarket OEM-style pipe (muffler connection was rusted), and within 50km, the car threw a PO420 code. I cleared the pending and the actual codes, but after my 15km drive to work this morning, I have another pending PO420.

I'm not sure of the brand of the exhaust (the muffler was a Walker), but it was said to have 3000km. I believe it since I removed it myself and the spring bolts on the manifold were easy as butter to remove.

I kept my original O2 sensors, but I didn't disconnect the downstream sensor and the wires *did* get pretty twisted when I was unscrewing it, despite my being very careful.

I put a lot of anti-seize compound on the threads of the O2 sensors, but I was careful not to put any on the sensors themselves.

I installed a Borla center-exit muffler at the same time. It sounds great! at least 20 extra HP! Maybe even 50! LOL



What are your thoughts? Are aftermarket cats as efficient as Toyota cats? I still have my original midpipe and I guess I could chop it up and replace the resonator with a Walker 54657. What about O2 sensors?

Thank you.
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Old 06-08-2016, 09:39 AM   #2
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The cat on your midpipe could be toast and/or the wires could be damaged.

Swap in your original one and if the code doesn't come back then you know it's not your wires. The oem cat is a large diameter straight through design and is not restrictive. If you want to do anything then you can just remove the cat that has no sensor behind it. I did that and I have no cel's and no bad exhaust smell. The 2 cats are only for cold start emissions.

Edit*. I have a yaris so not sure if the Echo had 2 cats or not
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Old 06-08-2016, 09:51 AM   #3
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Quote:
Originally Posted by AlaxyGalaxy View Post
I swapped my Toyota midpipe (2004 Echo HB) for a used aftermarket OEM-style pipe (muffler connection was rusted), and within 50km, the car threw a PO420 code. I cleared the pending and the actual codes, but after my 15km drive to work this morning, I have another pending PO420.

I'm not sure of the brand of the exhaust (the muffler was a Walker), but it was said to have 3000km. I believe it since I removed it myself and the spring bolts on the manifold were easy as butter to remove.

I kept my original O2 sensors, but I didn't disconnect the downstream sensor and the wires *did* get pretty twisted when I was unscrewing it, despite my being very careful.

I put a lot of anti-seize compound on the threads of the O2 sensors, but I was careful not to put any on the sensors themselves.

I installed a Borla center-exit muffler at the same time. It sounds great! at least 20 extra HP! Maybe even 50! LOL



What are your thoughts? Are aftermarket cats as efficient as Toyota cats? I still have my original midpipe and I guess I could chop it up and replace the resonator with a Walker 54657. What about O2 sensors?

Thank you.
Correction 1hp more... lol
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Old 06-08-2016, 09:54 AM   #4
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Thank you for your response.

It would be hard to put the original midpipe back since I had to cut it at the muffler end to get it out. I can't attach a muffler anymore. I just now moved my car two blocks (Montreal parking...) and there are no pending codes.

Since it isn't instantaneous, I can't i myself driving around for 50 kms without a muffler.

That Walker resonator is only 38$ canadian, though. So I might just go with that.

FYI, the Echo hatches do not have two cats.
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Old 06-08-2016, 09:59 AM   #5
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A Po420 is either the cat or the sensor nearest to the engine is faulty. Can also be due to an exhaust leat in that same area.
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Old 06-08-2016, 12:53 PM   #6
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Could it be that I didn't tighten the spring bolts enough and that oxygen is seeping un at the downpipe gasket?

What about the anti seize compound fumes?
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Old 06-08-2016, 01:07 PM   #7
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Originally Posted by AlaxyGalaxy View Post
Could it be that I didn't tighten the spring bolts enough and that oxygen is seeping un at the downpipe gasket?

What about the anti seize compound fumes?
A leak can cause it but usually OB2 systems are too slow to detect that. Not like German VAG-COM that detects anything in a fraction of a second. Anti seize depending how much you put and how far in maybe but it would burn off quick. Temps are 500celcius plus. Maybe CT Scott will show up or someone else.

I replaced my exhaust system from header to tail pipe myself over 2 years ago, Magnaflow Cat and mid resonator freeflow. Welded my own bugs for 02 sensors no issues.
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Old 06-08-2016, 01:20 PM   #8
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I see your in Montreal.......we should meet one evening. I could drive over by the Orange Julip!!!
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Old 06-08-2016, 03:11 PM   #9
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Drives: 2004 Echo HB 5-door
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Yeah, I saw that too!

What is the "schedule" for the Julep these days?

Are there any evenings that are Toyota friendly ?
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Old 06-09-2016, 08:45 AM   #10
Rigaud
 
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Originally Posted by AlaxyGalaxy View Post
Yeah, I saw that too!

What is the "schedule" for the Julep these days?

Are there any evenings that are Toyota friendly ?
No clue on schedule and not really anything on Toyota specific I was told. I show up a few times in the summer either with my Yaris or Audi, only to meet up with some people and chat. Cops are always on the prowl there so I hesitate to go with my Yaris, but I do very quietly sometimes. lol
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Old 06-15-2016, 05:54 PM   #11
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Alright, so I borrowed a bluetooth OBD-II dongle from a coworker and managed to watch the two O2 sensors in real time.

Since I use a free version of an app, I can't log what I graph, but here is the gist of it:

B1S1 varies from 0 to 0.9 (volts, I'm assuming) continuously, and is affected by throttle input.

-When the cat is up to temperature, at idle and very little throttle, B1S2 is stable at around 0.8; that seems a little high to me.
-On compression or during a shift, B1S2 drops to zero, mimicking B1S1.
-At middle throttle, B1S2 mimicks B1S1 almost exactly
-I have not tried WOT.

Sometimes, with very little throttle, B1S2 will jerk up or down, then get back to being stable.

This behaviour seems quite odd to me: I was assuming that at temperature, B1S2 was supposed to stay stable at around 0.5-0.6V and not vary much at all. Mine is stable (albeit a tad higher), but only at low throttle input.

I have to admit I have absolutely no reference point. I think I'll plug the dongle in the Sienna and monitor one bank of sensors, just to see what a system that doesn't throw a CEL is supposed to look like.
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Old 06-16-2016, 12:21 AM   #12
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B1S1 will bounce up and down and is in control of the AFR of the engine. B1S2 is only there to measure the output of the Cat. O2 sensors are slow compared to the newer AFR sensors used on new cars, so it bounces back and forth trying to maintain 14.7 AFR.

The B1S2 should NOT read the same as B1S1. That indicated that the Cat is not working. It should bounce up and down, but much slower and not hold a higher reading for to long.

I had trouble after building my Turbo system with P0420. I built all my own exhaust and used the stock Cat in the system. I knew it just wasn't getting hot enough, fast enough, so I just recently built and installed a restrictor plate just behind B1S2 to slow down flow and keep the Cat hot and I haven't had a code since.
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Old 06-16-2016, 12:34 AM   #13
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Quote:
Originally Posted by AlaxyGalaxy View Post
Alright, so I borrowed a bluetooth OBD-II dongle from a coworker and managed to watch the two O2 sensors in real time.

Since I use a free version of an app, I can't log what I graph, but here is the gist of it:

B1S1 varies from 0 to 0.9 (volts, I'm assuming) continuously, and is affected by throttle input.

-When the cat is up to temperature, at idle and very little throttle, B1S2 is stable at around 0.8; that seems a little high to me.
-On compression or during a shift, B1S2 drops to zero, mimicking B1S1.
-At middle throttle, B1S2 mimicks B1S1 almost exactly
-I have not tried WOT.

Sometimes, with very little throttle, B1S2 will jerk up or down, then get back to being stable.

This behaviour seems quite odd to me: I was assuming that at temperature, B1S2 was supposed to stay stable at around 0.5-0.6V and not vary much at all. Mine is stable (albeit a tad higher), but only at low throttle input.

I have to admit I have absolutely no reference point. I think I'll plug the dongle in the Sienna and monitor one bank of sensors, just to see what a system that doesn't throw a CEL is supposed to look like.

It looks like your cat is operating as it should at idle and minimal throttle but is not doing it's job at middle throttle. Since most of time when you're driving you're using more than minimal throttle the ecu is recognizing the cat is not working right and hence the P0420 code.

O2 sensors produce output between 0.1V and 0.9V, with the presence of oxygen inhibiting or lowering the output voltage. A cat is used as a big hot (emissions fighting) furnace to burn off all the unburnt hydrocarbons exiting the engine and in the process using up the available oxygen to make C02 and H20. In a properly working system the B1S1 02 sensor will fluctuate up and down like a sine wave as the engine constantly switches between running too lean and too rich, and the B1S2 02 sensor will output a more stable mid to high voltage as the cat is using up most of the oxygen in the exhaust. So my suggestion would be go back to your stock cat and get that Walker mid pipe.

There's a bunch of good videos on youtube explaining the P0420 code and cat inefficiency.

https://www.youtube.com/watch?v=vKLFO8MF7SY

https://www.youtube.com/watch?v=vKLFO8MF7SY
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Old 07-07-2016, 10:50 AM   #14
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Drives: 2004 Echo HB 5-door
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Originally Posted by Bluevitz-rs View Post
I had trouble after building my Turbo system with P0420. I built all my own exhaust and used the stock Cat in the system. I knew it just wasn't getting hot enough, fast enough, so I just recently built and installed a restrictor plate just behind B1S2 to slow down flow and keep the Cat hot and I haven't had a code since.
Yeah, I'm wondering if that Borla high-flow muffler has anything to do with it. I tried a different B1S2 sensor (from a 99k Km 2001 Echo) and the result is the same. I also have a B1S1 sensor from a 2003, but that car had over 200k Km.

I'll give it a shot anyway (it's pretty easy to swap out a sensor), but if that doesn't work, I'm going to pick up a Walker cat-back pipe for 35$ and hope for the best, I guess.
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