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post #11 of 51 (permalink) Old 10-23-2017, 09:49 PM
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Originally Posted by zzleapy View Post
Dr. Feelgood. Need your help regarding the removing the Cat and bank1 pre cat. Just managed to have the time to work on the car again. I've managed to remove all the bolts to the exhaust (except the headers). I can't get the darn things out from the loop area. Did you have remove anything else? I've jacked the car about 16" off the ground, can't managed to get that (flat cat) out. Any suggestions.

Thanks.
So, you are in it... You can take the top bolt out of the passenger side engine mount and jack the car up a but to get more clearance. I unbolted both front (flat) and rear (flat) cats from the manifold (pre-cat) and had to bend the power steering rack heat shield a bit to get it. The heat shield comes out with two 8mm bolts and that would help a bit. The flex pipe is quite a puzzle. drop the rear rotate counter-clockwise and lean the back part towards the driver side...all at the same time.
I'll send you a link at the end describing what I did (both times, because I only replaced one of the cats and the others were right behind and failed later causing the first one to fail again...)

I have included a bit of info here Help me save Mozzie - Loss of Power

It is a huge pain, as you are discovering. I would recommend replacing all the cats and manifolds. You already did the O2 sensors and I would replace the remaining coils as well. One already failed and if any more go then it will nuke the new cats.

Is the cat pictured the one you are trying to remove? Or are you trying to get the 180 degree bend (at the base of the elbow) out?


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post #12 of 51 (permalink) Old 10-23-2017, 11:50 PM
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If you have a misfire... ESPECIALLY with that mileage, the FIRST thing to do is the plugs and COP coils... ALL of them. If you don't solve the misfire, you'll trash the new pre cats and you'll need yo do that lame job a second time. Please please replace your plugs and coils.
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post #13 of 51 (permalink) Old 10-24-2017, 07:03 PM
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Originally Posted by zzleapy View Post
An Update... Ended up swapping out the Coil drove about 400 miles.. no misfire pop up ... yet. So back to the P0421 code... I hooked up my torque app ODBII reader.. Bank 2x2 is reading at .8v at idle, and it'll mirror 2x1 graph when the RPM is at 2500 which I believe that sensor is bad? Are you guys replacing this precat? Which is Bank 2, the sensor 2x2 is the one below near the radiator. But the code P0421 is near the firewall?? which one is bad?


Just for the record. A P0431 and P0421 are both warm-up catalyst (pre-cat) related. This code will come up if the downstream O2 sensor, the ones after the warm-up catalyst (#1 & #3) fluctuates voltage too quickly

How it works:
The O2 sensor monitors the hydrocarbon level of the exhaust and adjusts the fuel mixture accordingly depending on if it is too rich or lean. This is why that O2 sensor (both upstream B1S1, B2S1) will fluctuate voltage wildly between 0.1 (lean) - 1.0 (rich) Volt. the downstream oxygen sensor (B1S2, B2S2) will measure hydrocarbon after the catalyst to see if it is functioning. This downstream sensor should read a relatively steady voltage. If the voltage fluxuation is looking the same as the upstream sensor (moving widely between near zero and one volt) then the PCM (computer) gives you a P0421 or P0431 code after being logged on two consecutive drive cycles.


1 = Bank 2 warm-up catalyst (pre-cat)
2 = Bank 2 TWC (three-way catalyst) catalytic converter
3 = Bank 1 warm-up catalyst (pre-cat)
4 = Front pipe (flex pipe)
5 = Bank 1 TWC (three-way catalyst) catalytic converter
6 = Presilencer (resonator) - not pictured on OEM exhaust but would bolt directly downstream from bank 1 TWC.

The P0421/P0431 is almost never the fault of a faulty O2 sensor. As sensors age and reach the end of their lifespan (50,000mi for a 2 lead, 70,000mi for a 3-lead, 100,000mi for a 4 lead) or (0.1V-1.0V response > 300 milliseconds) they tend to respond slower. This would reduce your effective regulation of mixture and also slow the response telling you that a cat was bad. this would mean you are less likely to show a P0421/431 code but more likely to destroy your catalyst due to improper fuel mixture regulation.

If your pre-cat/warm-up cat/manifold goes bad it is most likely a result of a long standing misfire (P0300.301,302,303...etc) This cat will disintegrate due to prolonged overheating (what gives you the sulfur smell) and travel downstream to clog the rear catalyst (if it does not also get sucked back into the intake via the EGR).
If you replace the front catalysts only then the increased back pressure from clogging/decaying rear catalysts will destroy the front ones within 20-50K miles (estimate)

The only solution that results in a correct long term fix is to:
1. Eliminate the misfire (usually COP's and Spark Plugs x6 in the Mazda 6 3.0 v6)
2. Replace all 4 catalytic converters. (Bank 1 and Bank 2 warm-up catalysts and TWC)
3. Replace all 4 oxygen sensors

In 2017 the total cost of parts for this job is as follows:

(Rockauto)
MFG / Part # / Desc.
Walker 464 16413 - Manifold/pre-cat
Walker 464 16414 - Manifold/pre-cat
Eastern Catalytic EMI 40627 - Catalytic Converter
Eastern Catalytic EMI 40626 - Catalytic Converter
NTK NGK 22097 - O2 sensor
NTK NGK 22118 - O2 sensor
NTK NGK 22100 - O2 sensor
NTK NGK 22115 - O2 sensor
Beck Arnley 037-8102 - Exhaust Manifold Gasket Set
DENSO 673 6005 - Ignition Coils x6
Mazda AJTT-18-110 - Spark Plugs x6
OEM 9XG01732S - manifold studs (x12)
OEM 9XG0170602 - manifold nuts (x12)


Total Cost : $1379.03 USD (price also included engine air filter, oil filter and replacement rear wiper blade)


Total labor time is about 6-8 hrs (working on the floor)

unless you have a broken manifold stud. Then add 20 hrs +/- (the v6 likes to break off the bank one above the alternator)




In order to remove the section it is usually necessary to unbolt everything except the manifolds (warm-up cats) and starting forward of the presilencer (resonator) and continue forward.
Taking off the two 8mm bolts from the power steering shield and removing it will help with clearance.
If you need more space to access the bank 2 TWC then you can remove the bolt from the passenger engine mount and jack up the motor a small amount.
The difficult part is removing the front pipe/flex-pipe. This needs to be lowered from the rear and pivoted towards the driver-side. While lowered and pivoted it needs to be rotated anti-clockwise (from the perspective of facing forward)
I was able to lay under the car with my feet towards the rear. I would support the back of the flex pipe with my knees while I rotated and worked the 180 degree bend up and over the steering rack.

If this is too difficult then you could remove the 4 bolts and 2 nuts from the cross-member rear support plates and move the entire crossmember/steering rack/engine (use a support) down a few inches.
Lowering the crossmember too much without disconnecting the 3 steering rack bolts will damage the rack (very expensive).

Pay attention to how it finally comes out because it will have to go in the same way.

Good luck.
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post #14 of 51 (permalink) Old 10-25-2017, 02:01 AM
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I so fear the day I have to do this job. Your comment about replacing the O2 sensors to get accurate fuel metering to avoid a failed pre cat makes me want to go do that right now. I'm at 106K and haven't replaced them in my short term of ownership.

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post #15 of 51 (permalink) Old 10-25-2017, 03:08 PM
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Quote:
Originally Posted by waughoo View Post
I so fear the day I have to do this job. Your comment about replacing the O2 sensors to get accurate fuel metering to avoid a failed pre cat makes me want to go do that right now. I'm at 106K and haven't replaced them in my short term of ownership.
I know how you must feel. I am hyper aware about misfires. I have an auto trans and when the torque converter locks and unlocks (even without me changing pedal pressure, such as grade change and load change) it feels like a hesitation. In essence, it is, but not due to a failure to ignite combustion.

I think the variance is small with regard to O2 sensors, other than outright failure. I would imagine a slow O2 sensor may make less of a difference than say changing from mostly highway driving to city driving. There the amount of fuel input and cylinder temps/exhaust hydrocarbon load are a far greater variance.

If you have not replaced your COP's and plugs by 100,000mi I would make this a preventative priority. Take out your crank and cam position sensors and wipe off the accumulated metal buildup. After that, consider replacing the O2 sensors and stay on top of vacuum leaks as the rubber gets old. Make sure your check engine light works or check your code status regularly.

You are aware enough I don't think you will have a problem. There are users on this sight that have exceeded 200,000 mi and never replaced catalysts without issue.

Preventative maintenance is paramount.

That's my 2-cents

Happy Motoring


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post #16 of 51 (permalink) Old 10-25-2017, 03:46 PM
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When I go back to having converters I am going to install 4 new O2's. Mine are unknown and I already have CEL on all the time so. One thing these cars are not is cheap to fix when you work on the front half of the exhaust.

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post #17 of 51 (permalink) Old 10-25-2017, 03:53 PM
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Quote:
Originally Posted by DrFeelGood View Post

If you have not replaced your COP's and plugs by 100,000mi I would make this a preventative priority. Take out your crank and cam position sensors and wipe off the accumulated metal buildup. After that, consider replacing the O2 sensors and stay on top of vacuum leaks as the rubber gets old. Make sure your check engine light works or check your code status regularly.

You are aware enough I don't think you will have a problem. There are users on this sight that have exceeded 200,000 mi and never replaced catalysts without issue.

Preventative maintenance is paramount.

That's my 2-cents

Happy Motoring
The valve cover gaskets and 6 new denso COP coils and iridium plugs + PCV valve and new dealer hose was the first job I did when I purchased the car at 89K miles. I haven't replaced the O2 sensors or cleaned this position sensors yet. Might have to ratchet that up the list a bit.

Alex
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post #18 of 51 (permalink) Old 10-25-2017, 08:02 PM
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... One thing these cars are not is cheap to fix when you work on the front half of the exhaust.
You are not kidding there. The dealer quoted me $4700 USD to do the job, ($3500 vehicle value) and not including COP's and plugs. That estimate was also not including the drilling of the broken manifold stud that had to be done blind (20 hrs) the first time I replaced only the pre-cats.

The car now runs great, even if I am on constant suicide watch with it. I'm determined to make Duratech live up to its name.


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post #19 of 51 (permalink) Old 10-25-2017, 08:17 PM
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Quote:
Originally Posted by DrFeelGood View Post
You are not kidding there. The dealer quoted me $4700 USD to do the job, ($3500 vehicle value) and not including COP's and plugs. That estimate was also not including the drilling of the broken manifold stud that had to be done blind (20 hrs) the first time I replaced only the pre-cats.

The car now runs great, even if I am on constant suicide watch with it. I'm determined to make Duratech live up to its name.
Same here, I have about $900 into my headers and the install. Should be another $300-400 to have a new midpipe made up. Another $300 or so for all new o2 sensors. Never ends, lol.

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post #20 of 51 (permalink) Old 12-04-2017, 05:26 PM Thread Starter
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Quote:
Originally Posted by DrFeelGood View Post
Just for the record. A P0431 and P0421 are both warm-up catalyst (pre-cat) related. This code will come up if the downstream O2 sensor, the ones after the warm-up catalyst (#1 & #3) fluctuates voltage too quickly

How it works:
The O2 sensor monitors the hydrocarbon level of the exhaust and adjusts the fuel mixture accordingly depending on if it is too rich or lean. This is why that O2 sensor (both upstream B1S1, B2S1) will fluctuate voltage wildly between 0.1 (lean) - 1.0 (rich) Volt. the downstream oxygen sensor (B1S2, B2S2) will measure hydrocarbon after the catalyst to see if it is functioning. This downstream sensor should read a relatively steady voltage. If the voltage fluxuation is looking the same as the upstream sensor (moving widely between near zero and one volt) then the PCM (computer) gives you a P0421 or P0431 code after being logged on two consecutive drive cycles.


1 = Bank 2 warm-up catalyst (pre-cat)
2 = Bank 2 TWC (three-way catalyst) catalytic converter
3 = Bank 1 warm-up catalyst (pre-cat)
4 = Front pipe (flex pipe)
5 = Bank 1 TWC (three-way catalyst) catalytic converter
6 = Presilencer (resonator) - not pictured on OEM exhaust but would bolt directly downstream from bank 1 TWC.

The P0421/P0431 is almost never the fault of a faulty O2 sensor. As sensors age and reach the end of their lifespan (50,000mi for a 2 lead, 70,000mi for a 3-lead, 100,000mi for a 4 lead) or (0.1V-1.0V response > 300 milliseconds) they tend to respond slower. This would reduce your effective regulation of mixture and also slow the response telling you that a cat was bad. this would mean you are less likely to show a P0421/431 code but more likely to destroy your catalyst due to improper fuel mixture regulation.

If your pre-cat/warm-up cat/manifold goes bad it is most likely a result of a long standing misfire (P0300.301,302,303...etc) This cat will disintegrate due to prolonged overheating (what gives you the sulfur smell) and travel downstream to clog the rear catalyst (if it does not also get sucked back into the intake via the EGR).
If you replace the front catalysts only then the increased back pressure from clogging/decaying rear catalysts will destroy the front ones within 20-50K miles (estimate)

The only solution that results in a correct long term fix is to:
1. Eliminate the misfire (usually COP's and Spark Plugs x6 in the Mazda 6 3.0 v6)
2. Replace all 4 catalytic converters. (Bank 1 and Bank 2 warm-up catalysts and TWC)
3. Replace all 4 oxygen sensors

In 2017 the total cost of parts for this job is as follows:

(Rockauto)
MFG / Part # / Desc.
Walker 464 16413 - Manifold/pre-cat
Walker 464 16414 - Manifold/pre-cat
Eastern Catalytic EMI 40627 - Catalytic Converter
Eastern Catalytic EMI 40626 - Catalytic Converter
NTK NGK 22097 - O2 sensor
NTK NGK 22118 - O2 sensor
NTK NGK 22100 - O2 sensor
NTK NGK 22115 - O2 sensor
Beck Arnley 037-8102 - Exhaust Manifold Gasket Set
DENSO 673 6005 - Ignition Coils x6
Mazda AJTT-18-110 - Spark Plugs x6
OEM 9XG01732S - manifold studs (x12)
OEM 9XG0170602 - manifold nuts (x12)


Total Cost : $1379.03 USD (price also included engine air filter, oil filter and replacement rear wiper blade)


Total labor time is about 6-8 hrs (working on the floor)

unless you have a broken manifold stud. Then add 20 hrs +/- (the v6 likes to break off the bank one above the alternator)




In order to remove the section it is usually necessary to unbolt everything except the manifolds (warm-up cats) and starting forward of the presilencer (resonator) and continue forward.
Taking off the two 8mm bolts from the power steering shield and removing it will help with clearance.
If you need more space to access the bank 2 TWC then you can remove the bolt from the passenger engine mount and jack up the motor a small amount.
The difficult part is removing the front pipe/flex-pipe. This needs to be lowered from the rear and pivoted towards the driver-side. While lowered and pivoted it needs to be rotated anti-clockwise (from the perspective of facing forward)
I was able to lay under the car with my feet towards the rear. I would support the back of the flex pipe with my knees while I rotated and worked the 180 degree bend up and over the steering rack.

If this is too difficult then you could remove the 4 bolts and 2 nuts from the cross-member rear support plates and move the entire crossmember/steering rack/engine (use a support) down a few inches.
Lowering the crossmember too much without disconnecting the 3 steering rack bolts will damage the rack (very expensive).

Pay attention to how it finally comes out because it will have to go in the same way.

Good luck.
Hey Doc, So I was able to get all 5 bolts/stems off. Two stems came off before the nuts. However, the top right (behind the alternator) was broken already. I was worried how I was going to get that off, without removing the alternator. So, looking this post, you had a picture of your snapped stem bolt, is this the same one (top right stem?) Was yours broken before, or was it broken while your attempt to remove it? I assuming after breaking the stem, you removed the Alternator? I think might have to, seems pretty tight to get a drill in there to set a hole for the reverse thread bit. Suggestion?



Thanks.
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