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Discussion Starter #1
Have an 2003 3.0L MTX that just started having hard starts and a bad knock around 1000-1500 RPMs. Also has a weird ping when under acceleration, sounds like a little diesel rabbit from the 80's. Lastly, she is drinking about a quart of oil between oil changes. The first thing that comes to mind is pre cat failure and start pricing out a new block. Anything else come to mind with those symptoms? Is there anything I can do to stall doing a engine replacement? Will cleaning out the pre cats do anything to help or am I already up the creek.

The car has 90K on it and is my daily commuter, she only sees about 15 miles a day and we use my wifes car for everything else, so the longer I can stall this or bandaid the problem the better.

-Svence
 

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Have an 2003 3.0L MTX that just started having hard starts and a bad knock around 1000-1500 RPMs. Also has a weird ping when under acceleration, sounds like a little diesel rabbit from the 80's. Lastly, she is drinking about a quart of oil between oil changes. The first thing that comes to mind is pre cat failure and start pricing out a new block. Anything else come to mind with those symptoms? Is there anything I can do to stall doing a engine replacement? Will cleaning out the pre cats do anything to help or am I already up the creek.

The car has 90K on it and is my daily commuter, she only sees about 15 miles a day and we use my wifes car for everything else, so the longer I can stall this or bandaid the problem the better.

-Svence
I would clean the pre cats.. sounds like what most people are having around your milage... the thing is that I won't put a bandaid on it... it's your engine bro... 4000 for a new one.... not including install... Check your PVC valves...

Alot of people have had good results cleaning out the precats.. you might want to get new headers and to get rid of the precats..
MSDS Headers. This would be a better solution then cleaning them out...

Mazda6 precat and engine failure poll.
Pre Cat Failure Situation
Engine Replaced - 72500mi Due to CAT failure.


 

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I would clean the pre cats.. sounds like what most people are having around your milage... the thing is that I won't put a bandaid on it... it's your engine bro... 4000 for a new one.... not including install... Check your PVC valves...

Alot of people have had good results cleaning out the precats.. you might want to get new headers and to get rid of the precats..
MSDS Headers. This would be a better solution then cleaning them out...

Mazda6 precat and engine failure poll.
Pre Cat Failure Situation
Engine Replaced - 72500mi Due to CAT failure.


Nice post, but neither will solve his problem. If he's already having hard knocking I'd lay down $5 that he's gonna spin a rod bearing before Christmas.

As for a new motor. I got a used motor with 60k on it for $3.8k but it came with a 3 year unlimited mile parts and labor warranty.
 

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Nice post, but neither will solve his problem. If he's already having hard knocking I'd lay down $5 that he's gonna spin a rod bearing before Christmas.

As for a new motor. I got a used motor with 60k on it for $3.8k but it came with a 3 year unlimited mile parts and labor warranty.

your half right on that.. He will eventually still need an engine. Totally agree with that... but instead of buying new cats which he will run into the problem again he needs headers... MSDS are the cheaper one and a lot of people recommend them...

For now he needs to get those precat out and change the oil is what some people say has helped them till they can replace the engine.
 

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your half right on that.. He will eventually still need an engine. Totally agree with that... but instead of buying new cats which he will run into the problem again he needs headers... MSDS are the cheaper one and a lot of people recommend them...

For now he needs to get those precat out and change the oil is what some people say has helped them till they can replace the engine.
Oh I wasn't even talking about replacing the cats. I was just saying his motor is going to be toast one way or another by the sound of it. I wouldn't even bother with the headers if he's positive it's his rod bearing getting ready to seize up. I'd save the $700 and put it towards a new engine.
 

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Discussion Starter #7
I know headers sound like a good idea if I plan on doing more upgrades but what about just gutting the precats? I would rather not drop another couple hundred bucks on headers on top of a x thousand dollars for a new engine. If I could just gut the precats and fix the problem (for future a future engine, i know the damage is probably already done here) would I get the same results?

-Svence
 

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Discussion Starter #8
And forgot to mention, I have had a metallic rattle, sounds like a loose bolt on metal for a while now. Could that be the ceramic in the precat?

I feel like I am check every box on the path to precat failure = engine replacement :(

-Svence
 

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And forgot to mention, I have had a metallic rattle, sounds like a loose bolt on metal for a while now. Could that be the ceramic in the precat?

I feel like I am check every box on the path to precat failure = engine replacement :(

-Svence

Sounds like metal shavings from the precats.. I would take a look at them and see if they are gone..

Read this post...
http://forum.mazda6club.com/3-0l-v6/238975-pre-cat-failure-situation.html

i would do this soon before the engine gets worst....
 

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Discussion Starter #10
Sounds like metal shavings from the precats.. I would take a look at them and see if they are gone..

Read this post...
http://forum.mazda6club.com/3-0l-v6/238975-pre-cat-failure-situation.html

i would do this soon before the engine gets worst....

Yup, read that this afternoon, seems like I may be able to salvage what I have now. Going to be pulling the precats off this week (hopefully Wednesday), any how-to's on here? I know its a simple jack, unbolt the exhaust, chip away, and hope for the best, but I am a pictures kind of guy :D

Anyone with a sweet write up?

-Svence
 

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Have an 2003 3.0L MTX that just started having hard starts and a bad knock around 1000-1500 RPMs. Also has a weird ping when under acceleration, sounds like a little diesel rabbit from the 80's. Lastly, she is drinking about a quart of oil between oil changes. The first thing that comes to mind is pre cat failure and start pricing out a new block. Anything else come to mind with those symptoms? Is there anything I can do to stall doing a engine replacement? Will cleaning out the pre cats do anything to help or am I already up the creek.

The car has 90K on it and is my daily commuter, she only sees about 15 miles a day and we use my wifes car for everything else, so the longer I can stall this or bandaid the problem the better.

-Svence
I guess you have already figured out that it may very well be the precats.
In the best interests of the mazda6 community can you provide us the following information?

1. Type of oil & filter used
2. Oil change intervals
3. Type of Gas used
4. Last time when you changed the spark plugs
5. Last time when you changed the coil(s)
6. Mostly highway or mostly city driving?
7. Ever had any rocks or pebbles hit the undercarriage?
8. Any misfire history? How long did that last before you got it resolved?
9. mpg
10. Any loss of power experienced in the last 6 months or so?


Thanks!
 

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Discussion Starter #14
I guess you have already figured out that it may very well be the precats.
In the best interests of the mazda6 community can you provide us the following information?

1. Type of oil & filter used
2. Oil change intervals
3. Type of Gas used
4. Last time when you changed the spark plugs
5. Last time when you changed the coil(s)
6. Mostly highway or mostly city driving?
7. Ever had any rocks or pebbles hit the undercarriage?
8. Any misfire history? How long did that last before you got it resolved?
9. mpg
10. Any loss of power experienced in the last 6 months or so?


Thanks!
1. Full Synthetic - Mostly Pennzoil Platinum
2. 3500-5000 Miles
3. Cheap Stuff
4. 75K
5. Coils are original
6. Combined, I have had 1 hour commutes and 10 minute commutes, move around a lot.
7. Nothing out of the norm
8. Misfired for about a week, ended up being a loose spark plug
9. 24-27 mpg
10. Nope

-Svence
 

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Discussion Starter #15
And another symptom (trying to be as analytical as possible here)...

The Hard Start issue is only once the car has warmed up, this morning from a cold start she turned over like nothing. Got to work, turned it off and tried a restart, that's when I get the slow turn over (like a weak battery) and she takes a bit to get going and fire up.

Also had the CEL come on last night, will run the code this afternoon on my way home. 5 bucks to whoever can guess the error code ;)

-Svence
 

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I'm guess a cylinder misfire... P030N, N = the cylinder #

This would lead to new spark plugs and wires.. highly recommended...

I would say it is P0304 to be specific but It does sound like a P030N.

Let us know when you find out..
 

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I guess you have already figured out that it may very well be the precats.
In the best interests of the mazda6 community can you provide us the following information?

1. Type of oil & filter used Mobil 1 synthetic and oem filter
2. Oil change intervals - 5000 - I drive on the rough side but if it looks dark.. change sooner
3. Type of Gas used no mods so I use 87
4. Last time when you changed the spark plugs not yet only 50K
5. Last time when you changed the coil(s)not yet
6. Mostly highway or mostly city driving? about half and half
7. Ever had any rocks or pebbles hit the undercarriage? no...
8. Any misfire history? How long did that last before you got it resolved? not that i know of...
9. mpg unknows
10. Any loss of power experienced in the last 6 months or so? yea my clutch went... lol.. replacing with a stage 2 and 8lbs flywheel...


Thanks!
...
 

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Discussion Starter #19
Forgot to get the code number but it was Cam Position Overly Retarded or something along those lines.

Changed the oil today (was due regardless of the issues), no real change in what's going on under the hood.

-Svence
 

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