Mazda 6 Forums banner
261 - 280 of 304 Posts

·
Registered
Joined
·
382 Posts
Adding to this, I'm not getting the typical knock when a coil is really bad. So, I probalby don't have a coil issue, but I figured it was about 120k miles of lots of close range driving, so swapping out the plugs at least wouldn't be a bad idea. Just figured if the guy is in there, he can test the coils too.
 

·
Registered
Joined
·
382 Posts
^^ PS - a healthy engine should never knock. That doesn't sound good for its longevity.
Knock was probably a bad word to use. Just when the Coil is really bad and you get the misfire "bucking" or "shudder".

Update on me, I just had the throttle body serviced again and it seems to have all gone away. I wasn't getting the real tell tale signs of a bad coil like I have before.

Also, one of my lead's were bad, so that's what was messing up my headlight.

So far, I think I've replaced almost every single hose and seal in this sucker, so hope I get some more time out of it.
 

·
Registered
Joined
·
1 Posts
check engine light

I have a 2004 mazda 6 wagon 3.0l with a check engine light issue. I have no active codes yet after resetting the light and going for a 50 to 60 km drive in the city the check engine light comes on. The hard part is that living in Ontario we have manditory emission testing and this just started but go figure it just before I have to take mine in for the test. :mad: Any ideas ????? the o2 sensors have all been change and so have the coils. this is really frustrating. I anyone has had this issue I would like some help.
 

·
Registered
Joined
·
1,079 Posts
I have a 2004 mazda 6 wagon 3.0l with a check engine light issue. I have no active codes yet after resetting the light and going for a 50 to 60 km drive in the city the check engine light comes on. The hard part is that living in Ontario we have manditory emission testing and this just started but go figure it just before I have to take mine in for the test. :mad: Any ideas ????? the o2 sensors have all been change and so have the coils. this is really frustrating. I anyone has had this issue I would like some help.
Check your vac lines(esp pcv hose and tb hose).... How many miles on the car?

Sent from AutoGuide.com Free App
 

·
Registered
Joined
·
382 Posts
I have a 2004 mazda 6 wagon 3.0l with a check engine light issue. I have no active codes yet after resetting the light and going for a 50 to 60 km drive in the city the check engine light comes on. The hard part is that living in Ontario we have manditory emission testing and this just started but go figure it just before I have to take mine in for the test. :mad: Any ideas ????? the o2 sensors have all been change and so have the coils. this is really frustrating. I anyone has had this issue I would like some help.
with out checking what engine code you got before you reset it, no one here can help you. It could be anything.
 

·
Registered
Joined
·
148 Posts
^ Agrees.

I live in Ontario as well. You can goto any Partsource and they will read the code for you for free.
 

·
Registered
Joined
·
1 Posts
Same problem over here... got a 04 6s sportswagon 96000k on it. just got done replacing my trans by one of my buddies and it ran beautiful. about two weeks after my CEL came on so i went to autozone got the code read and was told that cylinder #1 had a missfire so i picked up 6pk of ngk platinum plugs. same day i replaced them only to run into this notorious problem of hesitation and stuttering 5th gear(low RPM) and in D stopped at a light etc. next day i started thinking of what could of been wrong soo i figured one of my vac hoeses were not put on right or maybe the gap was set wrong so i did a full inspection took out all the plugs cleaned everything properly, put it back together and ran it for about ten min. satisfied with the results i thought why not go for a lil test drive only to find the same problem again! It also throws NO code out !!!which is driving me nuts. I know that my wishbone trans mount is in a pretty bad shape so i'm currently waiting on that to come in hoping it will help me somewhat, but from what i read i'll just end up over here lookin for more answers/solutions. So from what i'm seeing the last and only thing left for me to do is to replace the coils. could anyone confirm that that's actually is the fix? i've noticed that it has helped a few but was it just for the time being.... Thanks,
Thanks for the details. Same kind of deal: 2004 Mazda6 Sport Wagon, 100K miles.
Here is a bit more information and results that may help others.

Bottom line: after replacing the spark plugs, the low rpm surging began. One CEL code thrown: no connection with downstream oxygen sensor.
-----------------
RPM surges at idle, between 350 and 900 rpm. Runs smoothly above 2K rpm under load without hesitation.
My problem began immediately after replacing the spark plugs.

What I did . . .
Replaced spark plugs with OEM Motorcraft. Gapped each to 44 (the plugs out of the box were gapped a bit wider, maximum 50). Put thread sealer on the threads and dielectric grease on the terminal.
Batter was disconnected.

After startup . . .
The rpm surging began immediately. Scary -- so much that after a few heart-pounding seconds, I killed the ignition.
Started and ran the engine a few more times.
No engine light.

Checks . . .
Vacuum lines were fine. Intake sensors clean. Throttle body firmly torqued down via a star pattern, starting with the inner 4 bolts. (I did 4 rounds of slowly torquing the bolts).
Electrical connections firm and clean.
EGR firmly connected. PCV valve is new and securely connected.

So Next . . .
Re-install the throttle body:
Cleaned out the red high temperature sealant (long story but it worked just fine alongside the Fel-Pros). Did NOT replace the Fel-Pro gaskets.

Performed a test drive for 1 hour. Ran smoothly over 1,200 rpm, even under hard acceleration. Used 93 octane fuel with Techron fuel system flush. Steady engine light appeared after 50 minutes of the test drive. No improvement in engine performance -- still surging at idle.

Findings so far . . .
Computer threw one code: a bad oxygen sensor (downstream). Thank you AutoZone.

Now what . . .
Replace the allegedly bad oxygen sensor. Carefully. That particular sensor costs about $55 at AutoZone.

Will update with results. My back is killing me.
 

·
Registered
Joined
·
10 Posts
hello there... although i dont own my mazda6 anymore i infact fixed the problem (rough idle stoped and hesitetion while crusing in 5th gear with low rpm) prior to lossing it(got totaled, t boned, not my fault :'( ) i had the car running flawlessly for over 15k the problem was the coils, once i replaced them, the car ran great! i replaced them all. if u guy have any question feel free to ask. good luck! Pic of my old car =
the interior =
pic of current car =
i have to say i miss my mazda
 

·
Registered
Joined
·
1 Posts
Hey guys. I registered here just to update this thread. I found it very useful and appreciate it. I have an 04 6 sport-wagon auto. Has had the issue for several thousand miles now. For a while i couldn't decide if it was the trans or an ignition issue. I would expect the car to set a MIL if it was an ignition failure. So i kept driving it to see what it would do. It FINALLY set a MIL this past Monday. P0303 miss-fire cylinder 3. I ordered a Denso coil pack from RockAuto.com for $32 along with 6 NGK plugs. Put them in last night and so far it seems the issue is resolved. For reference, number 3 is under the throttle body/egr valve area(Ford cylinder numbering) which receives the most heat. I would think this could be the issue on most of the cars. In my experience, when you have issues like this that are common, it ends up being the same position that is affected. It was about a 30 minute job to do the coil pack and plugs. Ford did a good job making it easy to work with.
 

·
Registered
Joined
·
4 Posts
Hesitation

I have a 2004 Mazda 6 that we have owned since new. It has 94 K miles. We let the car sit for a month and the hesitation started. I added a can of Seafoam and the hesitation stopped. It started again shortly after a fill up of gas. I added another can of Seafoam and the hesitation stopped. My guess is that the injectors are clogged. Any thoughts would be greatly appreciated. Thanks :confused:
 

·
Registered
Joined
·
13 Posts
It's the COIL

Last week driving 70 mph in the left lane-the car stumbled. Hard. Then it stumbled a couple of more times. Engine light flashed. My Ultragauge flashed up a P0302 cyl 2 misfire. The check engine light eventually went out but the stumble remained. Pretty much at all light load low rpm operation the car stumbled.

I read this entire thread. I replaced the rear bank coils and plugs because of time constraints, I will replace the front bank today.

Everything is good. I don't even have the minor stumble that I had attributed to the aging auto tranny.

It's the COIL.
 

·
Registered
Joined
·
29 Posts
List of repair items when replacing coils?

OK I've read this whole thread and I plan to replace the coils on my 04 wagon, 88K miles. I think it also has an oil leak from the rear valve cover gasket (I'm getting the burnt smell, it's starting to use oil, and I noticed staining below the rear valve cover while replacing the broken wishbone mount). While I'm doing it I might as well knock out a few other repairs / maintenance.

I'd appreciate any advice on this list (what to add or leave off):

- coils (I'm going to replace all 6)
- valve cover gaskets
- spark plugs
- PVC valve
- clean MAF sensor (I have an AEN dry filter CAI)
- check all vacuum lines, replace as needed
- oil control valve seal (?)
- gas cap (?)
- intake gasket (?)
- camshaft position sensors (?)
- O2 sensors (how to check if they are OK or not?)

Thanks for alll your advice, this is a GREAT asssociation!
 

·
Registered
Joined
·
1,079 Posts
OK I've read this whole thread and I plan to replace the coils on my 04 wagon, 88K miles. I think it also has an oil leak from the rear valve cover gasket (I'm getting the burnt smell, it's starting to use oil, and I noticed staining below the rear valve cover while replacing the broken wishbone mount). While I'm doing it I might as well knock out a few other repairs / maintenance.

I'd appreciate any advice on this list (what to add or leave off):

- coils (I'm going to replace all 6)
- valve cover gaskets
- spark plugs
- PVC valve
- clean MAF sensor (I have an AEN dry filter CAI)
- check all vacuum lines, replace as needed
- oil control valve seal (?)
- gas cap (?)
- intake gasket (?)
- camshaft position sensors (?)
- O2 sensors (how to check if they are OK or not?)

Thanks for alll your advice, this is a GREAT asssociation!
I would do all EXCEPT:

cam position sensors

Gas cap

Front 3 coils(the rear 3 coils take longer to change since the intake manifold has to be removed so you could save $ and time by only changing the back 3 coils)

Downstream O2 sensors(upstream control fuel, downstream are there to make sure precats are working)

I'm at 167k miles on 4 of my original ignition coils..misfire killed the other 2 coils when I waited soo long to change my plugs. I changed my upstream O2 sensors at 100k miles as preventive maintenance. I also need valve cover gaskets, my rear is leaking as well...

Oh yea, don't forget about ALL your fluids.



sent from my Galaxy S4
 

·
Registered
Joined
·
20 Posts
Wow, this thread has been going on for a while. I guess it's my turn to join the party..

My 2004 Mazda 6S Auto (145K miles) has been having this hesitation problem for a few months now. It intermittently hesitates (stutters) at idle and it doesn't matter if cold/warm/hot, does it in gear, rpm drops and you can feel the "thump". I think it does it in park/neutral, but can't feel it nor does the rpm drop, I only noticed it through the sound of the exhaust. And it hestitates when under load, around 40mph. Problem started before I did anything to the car. Also, no CEL, no pending codes.

So far I have:

Replaced all 6 spark plugs with OEM Motorcraft (factory gapped to .054).
Replaced all 6 coils (denso).
Replaced Upper Intake Manifold gaskets (used Magnum's, and seemed a little too big, but i figured the rubber would compress)
Replaced PCV valve
Replaced Intake Hose (cracked in two places)
Cleaned MAF
Checked PCV and other VAC hoses.

The problem persisted so I put in a bottle of Techron at fill up and made it all the way home, 20 miles without any hesitation, which seemed odd because I didn't think the techron would work that fast. And I didn't think much about it (thoughout the entire tank of gas/techron), until my next fill up (without Techron) and the hesitation returned. About 5 minutes after I pulled out of the gas station. Only thing I did to the car was change the AEM filter with the new red one (about 50 miles before fill up), other than that I open and close the gas cap.

I'm at a dead end here. I'm going to try cleaning the EGR valve next, not sure how it comes apart. Maybe perform a smoke test, but if it's a VAC leak, wouldn't the problem be more consistant? Also going to try another bottle of Techron. I may put the other AEM filter back on and it doesn't make much sense to me, but I guess I can try a new gas cap.

Any advice is greatly appreciated. Been following this site for years now and I've been able to fix most problems by just reading, but not this one.
 

·
Registered
Joined
·
1,079 Posts
Wow, this thread has been going on for a while. I guess it's my turn to join the party..

My 2004 Mazda 6S Auto (145K miles) has been having this hesitation problem for a few months now. It intermittently hesitates (stutters) at idle and it doesn't matter if cold/warm/hot, does it in gear, rpm drops and you can feel the "thump". I think it does it in park/neutral, but can't feel it nor does the rpm drop, I only noticed it through the sound of the exhaust. And it hestitates when under load, around 40mph. Problem started before I did anything to the car. Also, no CEL, no pending codes.

So far I have:

Replaced all 6 spark plugs with OEM Motorcraft (factory gapped to .054).
Replaced all 6 coils (denso).
Replaced Upper Intake Manifold gaskets (used Magnum's, and seemed a little too big, but i figured the rubber would compress)
Replaced PCV valve
Replaced Intake Hose (cracked in two places)
Cleaned MAF
Checked PCV and other VAC hoses.

The problem persisted so I put in a bottle of Techron at fill up and made it all the way home, 20 miles without any hesitation, which seemed odd because I didn't think the techron would work that fast. And I didn't think much about it (thoughout the entire tank of gas/techron), until my next fill up (without Techron) and the hesitation returned. About 5 minutes after I pulled out of the gas station. Only thing I did to the car was change the AEM filter with the new red one (about 50 miles before fill up), other than that I open and close the gas cap.

I'm at a dead end here. I'm going to try cleaning the EGR valve next, not sure how it comes apart. Maybe perform a smoke test, but if it's a VAC leak, wouldn't the problem be more consistant? Also going to try another bottle of Techron. I may put the other AEM filter back on and it doesn't make much sense to me, but I guess I can try a new gas cap.

Any advice is greatly appreciated. Been following this site for years now and I've been able to fix most problems by just reading, but not this one.
Wow all that and still hesitation...
Are the red AEM filters oiled? Might not be be a prob since k&n filters are used by many Mazda 6's, that are oiled too with no issues (that I know of).

Sent from AutoGuide.com Free App
 

·
Registered
Joined
·
29 Posts
OK got er dun - boy that 3.0l was shoe-horned in there, I think they had to lube the engine bay to slide it in. I'm happy to say that the hesitation is gone. there was oil in all the plug wells, indicating to me that the engine was under pressure, almost all the top-engine gaskets were seeping. The plugs were fouled, especially the rear bank, but engine was very clean, so I'm hoping there was no damage. I believe this whole mess was due to NOT CHANGING THE PVC VALVE ON SCHEDULE. There is no longer any "burning oil" smell at idle - therefore I think it was blowing oil vapor before due to an inoperable PVC valve. CHANGE THAT VALVE, IT'S CHEAP! Here's what I did, with a little note on issues I encountered:
- R&R intake manifold (note: no need to disconnect the throttle body and most of the fittings on it - just unbolt the intake heat riser, and leave the throttle body on the manifold.) BEWARE THE COOLANT BYPASS T-FITTING! I broke it, trip to dealer, $47, tore the CRAP out of my hands trying to replace the heater hose, COULDN'T DO IT! DAM this engine is squished into this car!
- R&R valve cover gaskets: BEWARE THE VARIABLE VALVE TIMING ACTUATOR GASKET - HIT IT WITH SOME WD40 BEFORE YOU TRY AND REMOVE THE COVERS OR YOU MAY DAMAGE THE GASKET! I did, and stuck an o-ring in the broken space, seems to work fine.
- replaced all 6 coils
- new valve cover gaskets (note: cleaned off and replaced a little dab of gasket sealer on the corners)
- spark plugs (note: get the plug threads started by holding and screwing them in with a "thin claw grabber" https://encrypted-tbn3.gstatic.com/...DfMAEfK0Zc36vymF71Zj2CgUiSQF7lml_8he6fg46sMAw
- PVC valve
- clean MAF sensor
- clean AEN dry air filter
- check all vacuum lines - no problem

I was lucky. If you smell oil burning, TAKE ACTION IMMEDIATELY! change that PCV valve!
 

·
Registered
Joined
·
443 Posts
Wow, this thread has been going on for a while. I guess it's my turn to join the party..

My 2004 Mazda 6S Auto (145K miles) has been having this hesitation problem for a few months now. It intermittently hesitates (stutters) at idle and it doesn't matter if cold/warm/hot, does it in gear, rpm drops and you can feel the "thump". I think it does it in park/neutral, but can't feel it nor does the rpm drop, I only noticed it through the sound of the exhaust. And it hestitates when under load, around 40mph. Problem started before I did anything to the car. Also, no CEL, no pending codes.

So far I have:

Replaced all 6 spark plugs with OEM Motorcraft (factory gapped to .054).
Replaced all 6 coils (denso).
Replaced Upper Intake Manifold gaskets (used Magnum's, and seemed a little too big, but i figured the rubber would compress)
Replaced PCV valve
Replaced Intake Hose (cracked in two places)
Cleaned MAF
Checked PCV and other VAC hoses.

The problem persisted so I put in a bottle of Techron at fill up and made it all the way home, 20 miles without any hesitation, which seemed odd because I didn't think the techron would work that fast. And I didn't think much about it (thoughout the entire tank of gas/techron), until my next fill up (without Techron) and the hesitation returned. About 5 minutes after I pulled out of the gas station. Only thing I did to the car was change the AEM filter with the new red one (about 50 miles before fill up), other than that I open and close the gas cap.

I'm at a dead end here. I'm going to try cleaning the EGR valve next, not sure how it comes apart. Maybe perform a smoke test, but if it's a VAC leak, wouldn't the problem be more consistant? Also going to try another bottle of Techron. I may put the other AEM filter back on and it doesn't make much sense to me, but I guess I can try a new gas cap.

Any advice is greatly appreciated. Been following this site for years now and I've been able to fix most problems by just reading, but not this one.
I would spray some stuff around the intake manifold gaskets since they don't seem "correct". Also do you have the "BB" throttle body?
 

·
Registered
Joined
·
20 Posts
Wow, quick replies... Thanks everyone for your help. I think the hesitation is getting worse. It's now noticeable in park and neutral. I temporary "fixed" the hesitation on my way home by driving the car "hard" and at stop lights, I held the revs at just above 750 rpm. Is there some way to "up" the idle?

Wow all that and still hesitation...
Are the red AEM filters oiled? Might not be be a prob since k&n filters are used by many Mazda 6's, that are oiled too with no issues (that I know of).

No, it's dryflow. Bought it to replace the filter that came with the Mazdaspeed CAI. AEM 21-202DK. One thing I forgot to mention is an tiny oil leak near the front of the engine (front as in "towards the front of the car", near bank 6). I'm not exactly sure where is coming from, but it's been leaking for over 20k miles. The hesitation started about 4k miles ago.

I would spray some stuff around the intake manifold gaskets since they don't seem "correct". Also do you have the "BB" throttle body?
You mean as a vacuum test? That might be a bit difficult, the 6 gaskets are pretty much in the center of the intake manifold. I don't think I could get any fluid near the gaskets. I may just suck it up and go get the gaskets from the dealer. I have the "AA" throttle body. I was think about that as well, but I didn't the get the related CEL. Aren't they pretty expensive? I'll probably keep that option on the back burner.
 
261 - 280 of 304 Posts
Top