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Rally Racer
2004 Mazda 6s Wagon ATX
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Discussion Starter · #21 · (Edited)
Wonderful news and great information for the archive here on the board! Thanks for posting it up.

I've always been a bit dissappointed with my fuel economy. I check it regularly and haven't been above 24.6mpg yet. I've seen others report 28 (IIRC) and your post makes me wonder if the cats play a role there. What do you think?
I would agree. Anytime the engine is running more efficiently it makes more power per unit fuel. That means I use less fuel to do the same work. Gas saved.
I never used to have to worry about spinning tires unless I really flogged it. Now it is quite easy making a curb lane turn (right), especially on an incline. I fear I will now be eating tires. (a good problem considering the alternative).

For future reference, please post where you order from and if you don't mind, share how much you paid for all of it.
(Rockauto)
MFG / Part # / Desc.
Walker 464 16413 - Manifold/TWC
Walker 464 16414 - Manifold/TWC
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
Mazda 9XG0-17-32S - Exhaust Manifold Studs x12
Mazda 9XG0-17-0602 - Exhaust Manifold Nuts: x12

Total Cost : $1342.67 USD (price also included engine air filter, oil filter and replacement rear wiper blade)




PICTURED HERE WITH FELPRO GASKET
 

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Rally Racer
2004 Mazda 6s Wagon ATX
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Discussion Starter · #22 ·
Because this is where we started here are my post repair fuel trims. (Current codes P1410 & P0455, VAD and EVAP leak respectively)

{IDLE}
LTFT1 (-7.8)
LTFT2 (-10.2)

{2500 RPM}
LTFT1 (-8.6)
LTFT2 (-3.1)
 

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Hi. I want to do this to my wagon soon. The front Precat and 02 sensors were replaced before at 108k. The rear precat is now cracked at 134k and I want to replace that along with the other 2 oxygen sensors sensors, spark plugs, and COP.

Is there a write up to replace the rear precat? Can't seem to find a write up.
I found the write up on the spark plugs (sticky DIY), but there are no pics, so if you could also point me in the direction of a post with pics that would be wonderful.

I'm trying to bring this wagon back to life :)

Thank you!
 

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Rally Racer
2004 Mazda 6s Wagon ATX
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3,855 Posts
Discussion Starter · #24 · (Edited)
Hi. I want to do this to my wagon soon. The front Precat and 02 sensors were replaced before at 108k. The rear precat is now cracked at 134k and I want to replace that along with the other 2 oxygen sensors sensors, spark plugs, and COP.

Is there a write up to replace the rear precat? Can't seem to find a write up.
I found the write up on the spark plugs (sticky DIY), but there are no pics, so if you could also point me in the direction of a post with pics that would be wonderful.

I'm trying to bring this wagon back to life :)

Thank you!
Hello, it's not fun the first time but the reward is great. Start with a nice spray down with thread lube. I use mostly Blaster but liquid wrench or WD40 or anything will help.
Start forward of the resonator and learn the ratchet/extension/elbow/socket dance one bolt at a time.
I wrote a few steps down here.

A now largely defunct site 6crew, which also happens to be a goldmine of info, has a step-be-step

DIY: Stock Header Removal For The 3.0L V6 Engine How-To

If you check my statistics by clicking on my user name you can flip back a few pages and see all my posts.

Happy to answer questions when I can.
 

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Thank you! I am ordering parts today and will start this work once they come in.

I just read through your instructions and that does seem like a lot of steps. I had no idea you had to remove the alternator and belts. I've done it before on my old Subaru, so I'm not worried; I assume I do this for space issues. Guess I will add the alternator belt to my list of parts since I'll already have I off :)

Did you have any problems removing the alternator? I found a thread on here that says you have to remove suspension pieces to remove the alternator. That sounds ridiculous. http://forum.mazda6club.com/newbie-section/230763-04-alternator-removal-please-help.html


Also, about the bolts: I dont want to break them off. How long did you soak them? And did you get replacement bolts from Mazda? Somewhere else? Will they come off with hand tools? I don't have a torch to heat anything or air tools.

I'm sure I will have more questions, so thank you in advance for offering to answer.
 

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Rally Racer
2004 Mazda 6s Wagon ATX
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Discussion Starter · #26 · (Edited)
Thank you! I am ordering parts today and will start this work once they come in.

I just read through your instructions and that does seem like a lot of steps. I had no idea you had to remove the alternator and belts. I've done it before on my old Subaru, so I'm not worried; I assume I do this for space issues. Guess I will add the alternator belt to my list of parts since I'll already have I off :)

Did you have any problems removing the alternator? I found a thread on here that says you have to remove suspension pieces to remove the alternator. That sounds ridiculous. http://forum.mazda6club.com/newbie-section/230763-04-alternator-removal-please-help.html



I'm sure I will have more questions, so thank you in advance for offering to answer.
No problem

The alternator needs to be removed to take the manifold nut off the #1 cylinder (mine was broken and had to be drilled out). It comes out after the exhaust. (remember to re-install it before you bolt the exhaust back up, I did this, oops) The only sticky points are getting the belt off. I purchased a 1/2" breaker bar with a swivel head to do this (then it was easy), and getting the alternator plug off (lots of grunting and sore fingers).
Squeeze the green plug tab near the base

I did not have to remove any suspension parts. When the belt is off spin the idler pulleys for the serpentine. Mine were bad. Cheap and easy to replace at this point.
I did not have to lower the sub-frame. I did it the first time but soon realized it was not necessary with the right counter-clockwise twisting motion to get the curvy twin flex pipe over the steering rack heat shield. The EGR required an adjustable clamp and 3' breaker bar (before loosening the manifold bolts of course).

I soaked the exhaust bolts the night before (I am west coast on unsalted roads) and used almost all the bolts over again. I have an impact and used it when I could but with the extensions and swivels I mostly ended up hurting myself and used mainly hand tools as a result.
Replace the manifold studs/nuts with Mazda OEM. PLEASE. It is an aluminum head and drilling one out below the mating surface was a nightmare.


The remainder of the exhaust bolts can be replaced with whatever fits well (use anti-seize).

May the Force be with you.:nerd:
 

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Ok thank you for the pics. Before I order anything I'm going to take off the old pieces first before I get myself in debt :)

I'm in no rush to do this, but I'd like to get this fixed before the summer comes around. The car is just sitting now.

I'm on the west coast too (SF), so hopefully the bolts will come out after being soaked over night.

Another questions if you don't mind: you mentioned removing the egr valve and intake manifold. Should I do that first? For example:

Remove IM, egr valve
Remove most of the pre-cat exhaust bolts, then alternator
Finish removing pre-cat

I tried reading the thread about exhaust removal on 6crew but the link says I'm not allowed to read it (I don't understand why both Mazda threads I'm trying to learn from block users from reading information, but thats another story).

Thanks!

I'll post pictures (or start a new thread) when I start , which will be in about two weeks (I'm in holiday starting this weekend).
 

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Rally Racer
2004 Mazda 6s Wagon ATX
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Discussion Starter · #28 ·
Ok thank you for the pics. Before I order anything I'm going to take off the old pieces first before I get myself in debt :)

I'm in no rush to do this, but I'd like to get this fixed before the summer comes around. The car is just sitting now.

I'm on the west coast too (SF), so hopefully the bolts will come out after being soaked over night.

Another questions if you don't mind: you mentioned removing the egr valve and intake manifold. Should I do that first? For example:

Remove IM, egr valve
Remove most of the pre-cat exhaust bolts, then alternator
Finish removing pre-cat

I tried reading the thread about exhaust removal on 6crew but the link says I'm not allowed to read it (I don't understand why both Mazda threads I'm trying to learn from block users from reading information, but thats another story).

Thanks!

I'll post pictures (or start a new thread) when I start , which will be in about two weeks (I'm in holiday starting this weekend).
I understand waiting to see what you have before spending money. I usually have to minimize downtime and sometimes that comes at extra cost (still cheaper than professional garage)

You can do everything from below. Unless you change the coils and plugs there is no need to take off the intake manifold. The EGR tube is unbolted (un-nutted really) from the bottom. It is big and mine was stuck but eventually relented.
The alternator comes off after the flex pipe and before the rear manifold. Start at the collector/resonator where the pipe becomes single, then just work your way forward, unbolting one section at a time. The flex pipe comes out easier if you unbolt the all the brackets holding the cat that is next to the oil pan. Drop the rear of the flex pipe down as you rotate counter-clockwise and wiggle. The heat shield for the power steering rack gets a little bent but it makes putting everything back together easier. The only thing that you really need to do from the top of the engine is torquing the front manifold nuts when you are done.
Working on you back is tough and freeing old exhaust nuts is not fun but otherwise it is a pretty straight forward job. Make sure you have leverage.
 

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So I managed to remove 8 bolts last night. The first pic is what I saw when I first got underneath the car. The second pic has green circles around the bolts I took off. The red circle is the piece I can't understand how to take off. It's a bracket that looks impossible to get to. The precat is free from the bottom, but I feel stuck now. What do I do next? You said you didn't drop the subframe, but it seems impossible to go any further. Also, the steering rod (?) is in the way. What am I missing?

In your directions, you said to remove resenator bolts and then remove the 02 sensor. I can't even see the 02 sensor from here.
 

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Rally Racer
2004 Mazda 6s Wagon ATX
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Discussion Starter · #30 ·
So I managed to remove 8 bolts last night. The first pic is what I saw when I first got underneath the car. The second pic has green circles around the bolts I took off. The red circle is the piece I can't understand how to take off. It's a bracket that looks impossible to get to. The precat is free from the bottom, but I feel stuck now. What do I do next? You said you didn't drop the subframe, but it seems impossible to go any further. Also, the steering rod (?) is in the way. What am I missing?

In your directions, you said to remove resenator bolts and then remove the 02 sensor. I can't even see the 02 sensor from here.
Hey there, did you figure it out? Sorry, I had e-mail notification off for this thread by accident. The upper bracket stays put. Everything forward from the resonator comes off in segments, working forward. That pipe (with the 180 degree turn is what needs to come out to gain access. It is called the flex pipe. that flex pipe needs to be lowered from the rear (where it attaches to the rear catalyst). While you are lowering it you will also leed to move the rearward end towards the drivers side at the same time you are rotating it counter-clockwise. Drop (wiggle) move left (wiggle), rotate (wiggle). There may be some levered prying of the pipe and as long as you are only contacting the power steering rack heat shield it is okay. DO NOT PRY AGAINST FLUID LINES. The heat shield however is not a problem it it gets a bit deformed as long as it does not impede the movement of the tie rods.
 

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Hey there, did you figure it out? Sorry, I had e-mail notification off for this thread by accident. The upper bracket stays put. Everything forward from the resonator comes off in segments, working forward. That pipe (with the 180 degree turn is what needs to come out to gain access. It is called the flex pipe. that flex pipe needs to be lowered from the rear (where it attaches to the rear catalyst). While you are lowering it you will also leed to move the rearward end towards the drivers side at the same time you are rotating it counter-clockwise. Drop (wiggle) move left (wiggle), rotate (wiggle). There may be some levered prying of the pipe and as long as you are only contacting the power steering rack heat shield it is okay. DO NOT PRY AGAINST FLUID LINES. The heat shield however is not a problem it it gets a bit deformed as long as it does not impede the movement of the tie rods.
No problem, thank you. I've been slowly working on this car, so no worries :). It's currently just sitting on jack stands while I wrench a little bit at a time.

This past weekend I managed to take off about 5 more bolts!! These bolts attach the flex pipe. Now the whole flex pipe is loose, and I just have to figure out how to wrestle it out, which is what you said: wiggle, left, down, wiggle, etc.

I think what's confusing is the terms: I'm not familiar with all the terms mean: flex pipe, resonator, etc. I've figure it out along the way, except for the resonator.

In one of the previous posts, you said start from the resonator (the piece where the pipe becomes single) and move forward. Am I correct in assuming it's the long pipe from about the doors to the rear of the car? The diagram I have calls it the presilencer. Everything forward of that comes off (rear cat, flexpipe, cat brackets, alternator, then finally the precat/exhaust manifold. ). I was trying to twist the flex pipe out and couldn't see how to do so without taking the rear cat off because the studs on the flex pipe are getting in the way of turning.

Thank you again! I'm going to work on it again this weekend and will update.
 

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Hi again.

I've managed to take off the center resonator, the twin flex pipe, and the front right passenger side converter! Yay me. It was really difficult to remove the flex pipe and converter, you have to really squeeze the pipes past a shield, but you don't break anything.

Now I can clearly see the exhaust manifold and the 6 bolts that hold the manifold in place. This weekend I plan to take off the EGR pipe, alternator, and the exhaust manifold. I think it's safe to order the part about now
 

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Rally Racer
2004 Mazda 6s Wagon ATX
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Discussion Starter · #33 ·
Hi again.

I've managed to take off the center resonator, the twin flex pipe, and the front right passenger side converter! Yay me. It was really difficult to remove the flex pipe and converter, you have to really squeeze the pipes past a shield, but you don't break anything.

Now I can clearly see the exhaust manifold and the 6 bolts that hold the manifold in place. This weekend I plan to take off the EGR pipe, alternator, and the exhaust manifold. I think it's safe to order the part about now :)
Congratulations! Put some lube on the EGR nut. You are almost there. Don't shortcut the parts. I recommend doing all the cats, OEM exhaust studs and O2 sensors. I would also go with a quality exhaust manifold gaskets (like Beck Arnley for OEM or Felpro) rather than the ones that come with the catalysts.
 

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Project car Finally finished! Replaced the exhaust manifold/cat, 2 oxygen sensors, 6 spark plugs, PCV valve, the egr purge valve and valve solenoid, air filter, oil change, cabin air filter, and all wiper blades. Passed smog today!!

Thanks for your help!! I've attached pictures of the car.
 

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Rally Racer
2004 Mazda 6s Wagon ATX
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Discussion Starter · #35 ·
That is fantastic news! I am glad you got it back together and I bet it feels pretty satisfying. May you have many miles of trouble free motoring. If I could suggest one more thing. If it is an automatic I would recommend doing a 3x trans fluid replacement (I use Mobil 1 multi vehicle in my 2004 5spd auto) as transmissions are no longer made and 2-3 thousand to rebuild. You use special fluid if you are 6 speed Aisin.
 

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Project car Finally finished! Replaced the exhaust manifold/cat, 2 oxygen sensors, 6 spark plugs, PCV valve, the egr purge valve and valve solenoid, air filter, oil change, cabin air filter, and all wiper blades. Passed smog today!!

Thanks for your help!! I've attached pictures of the car.
Congrats man! Another wagon saved. What an accomplishment to get it all done by yourself. Here's to many happy wagon miles ahead.
 

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Nice! Glad to see another saved, these cars are meant to pile on the miles if you can avoid the rust.

I am getting ready to install a set of gently used CP-e headers with a catted mid pipe so I am just gonna cut off the old pipes, dreading those manifold to engine bolts though, lol.
 

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@DrFeelGood The service manual says exhaust leak can cause P0421. See below. We know the service manual can be wrong but I am hoping fixing the exhaust leak makes some difference. The downstream O2 sensor voltage is flat as it should be at low RPMs and only starts oscillating with upstream sensor when I accelerate as seen in the waveforms below. May be this means the catalyst is somewhat working. The long term fuel trim of Bank 1 is 10 so the bank is running lean may be due to a vacuum leak.
 

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Rally Racer
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Discussion Starter · #39 · (Edited)
@DrFeelGood The service manual says exhaust leak can cause P0421. See below. We know the service manual can be wrong but I am hoping fixing the exhaust leak makes some difference. The downstream O2 sensor voltage is flat as it should be at low RPMs and only starts oscillating with upstream sensor when I accelerate as seen in the waveforms below. May be this means the catalyst is somewhat working. The long term fuel trim of Bank 1 is 10 so the bank is running lean may be due to a vacuum leak.
Or it means that when at low RPM there is enough of a leak that it is not sending it downstream to be picked up by the downstream sensor.
I hope it works out for you.(y)
 

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Or it means that when at low RPM there is enough of a leak that it is not sending it downstream to be picked up by the downstream sensor.
I hope it works out for you.(y)
I tested the exhaust for leaks by attaching a leaf blower into one tail pipe and sealing other using a rubber glove and rubber band. There was a leak at the front bank O2 sensor and a huge one at the joint between flexible pipe and downstream main catalytic converter for rear bank i.e. right after downstream O2 sensor bank 1. I will tighten the front 02 sensor and have applied Exhaust seal the leaking joint in exhaust tube. Let's see if this makes a difference to P0421. Theoretically, a leak after the warm-up cat and before the main cat can suck oxygen and if the leak is big enough you can see more oxygen on the downstream O2 sensor than the upstream sensor which leads to false P0421 and a lean condition as the upstream O2 sensor sees more oxygen than it expects. This can eventually destroy the cat as the ECU tries to compensate by increasing positive fuel trim even though the extra oxygen isn't actually there in the cylinder. However I am hoping since the coils are brand new the combustion will be good enough to burn the extra fuel in the cylinder itself.
 

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