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Discussion Starter #1 (Edited)
I have been having this issue for several months now. I've brought my vehicle into the dealership several times as well. The first time I brought it in they ran some tests and 2 of my cylinders were misfiring anywhere from 40-60 times. The other 2 cylinders were misfiring around 1-5 times.

They switched the coil packs and the cylinders the coil packs were in were misfiring once again. So, they replaced the 2 coil packs leaving 2 new, 2 old. Unfortunately, the car was still "bogging (staggering when you are trying to accelerate)" when your trying to accelerate quickly. They told me it was the spark plugs because right before I brought it, the day before I bought Auto-Lite plugs to see if that would fix the issue and installed them; well it made it worse and the technician said to def. not use Auto-Lites in my engine. So, I took the car home and installed the OEM spark plugs. The car wasn't bogging as bad, but it was still doing it. I brought it back in the next day and they said "they couldn't re-produce the issue".

So, 1 month later, it's starting to do it on a daily basis yet again! and my car is backfiring ever so often. I brought it in again, and we took it for a test drive and we found my car was misfiring (again) not as bad but 1-4 misfires per trip. Here comes the fun part...

The technician (really cool guy) tried the following:

  1. Running and carbon something or other (put fluid in the vacuum system; im newb..)
  2. Tried driving the car without the O2 sensor so it ran lean and to see if the issue was still happening.
  3. Switched out the old OEM spark plugs with new OEM ones (They said this fixed it and had no issues after a 9 mile test drive).

Well, after only driving a day, I'm still noticing this issue mainly when I am trying to accelerate quickly in 3rd gear and fourth gear. The technician said it might be my injectors, or my other 2 coil packs.

I'm hoping some of you on here can help assess my situation as my warranty is ended but my dealership is still covering me because it was an issue that has been ongoing before my warranty ended. Also, the technician made the assumption that the injectors may need to be replaced, any thoughts on that?

Thanks ahead of time!
 

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Could be related to faulty crank position sensor or cam
position sensor?
 

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Discussion Starter #3 (Edited)
Could be related to faulty crank position sensor or cam
position sensor?
Not sure, but I can run it by them as an option. It's weird, because if I put on my after market intake/BOV, it seems to do it more (studdering), not much but still noticeable. When I have the stock BOV and Intake it does it less.

When the Auto-Lites were in, it was doing is EXTREMELY bad (felt like I was getting boost cuts).

Do you think it is the injectors? The technician said this might be the issue before they replaced the spark plugs and it supposedly "Ran fine for 9 miles".

Mind you, this doesn't happen all the time! but it does happen at least 2 times within a 20 minute trip.
 

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Any chance it could be your MAF sensor as well? I would think they would have checked this already.This may explain why it gets worse when you change your intake and bov, however I don't think this would cause all that misfiring. Is the bov set to recirc or vta? What kind of intake did you have on there? I wonder if your ECU shit the bed...
 

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Discussion Starter #5
Any chance it could be your MAF sensor as well? I would think they would have checked this already.This may explain why it gets worse when you change your intake and bov, however I don't think this would cause all that misfiring. Is the bov set to recirc or vta? What kind of intake did you have on there? I wonder if your ECU shit the bed...
What is the MAF? (Please be aware, I am a huge computer guy and have a small amount of knowledge of vehicles).

For my blow off valve, I purchased the following:
TurboSmart BOV Kit: MS3, MS6 & CX7

For my intake, I purchased the following:
StreetUnit/COBB Short Ram Intake: MAZDASPEED6

Mind you, it is almost equal when I have the aftermarket parts on when talking about the misfiring/bogging and backfiring.
 

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MAF is your Mass Air Flow sensor. It is that small square plasic thing that sits on top of your intake with a bunch of wires going to it. It measures the amount of air coming in (in grams/sec) so your car knows how much fuel to add. I don't think it's this though.

When your car is misfiring, your ECU (car's computer) will pull timing and dump fuel to combat it. When you are running very rich, you can backfire. So, if your car is misfiring, that would explain the ECU dumping excess fuel in there, thus you running rich and backfiring.

Something is definitely wrong here... I don't know why your car is misfiring so much unless it's related to timing, what Groceries said, or your ECU is fried somehow. Did you add any electrical components to the car, such as an aftermarket stereo, etc? A bad short is the only thing I can think of that would fry your ECU, but they can just die on their own. It's more likely what Groceries said, but I don't know anything about those sensors.
 

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Discussion Starter #7
MAF is your Mass Air Flow sensor. It is that small square plasic thing that sits on top of your intake with a bunch of wires going to it. It measures the amount of air coming in (in grams/sec) so your car knows how much fuel to add. I don't think it's this though.

When your car is misfiring, your ECU (car's computer) will pull timing and dump fuel to combat it. When you are running very rich, you can backfire. So, if your car is misfiring, that would explain the ECU dumping excess fuel in there, thus you running rich and backfiring.

Something is definitely wrong here... I don't know why your car is misfiring so much unless it's related to timing, what Groceries said, or your ECU is fried somehow. Did you add any electrical components to the car, such as an aftermarket stereo, etc? A bad short is the only thing I can think of that would fry your ECU, but they can just die on their own. It's more likely what Groceries said, but I don't know anything about those sensors.
They tried running the car without the MAF and they said that the vehicle was still having the issue. The only thing I have installed after market to anything electrical is a Prosport Boost Gauge and an Ipod/Aux adapter unit.

So, you may think it's the ECU? hmm, I will run that by them now.
 

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Do you have any way to monitor spark advance or fuel parameters, OP?

Your jumping to a totally seperate circuit from spark to fuel. I don't think it'd be injectors. Misfire would be from a physical timing issue, sensor or plug/coil problem. Backfires could be from unignited charge mixture?
 

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They tried running the car without the MAF and they said that the vehicle was still having the issue. The only thing I have installed after market to anything electrical is a Prosport Boost Gauge and an Ipod/Aux adapter unit.

So, you may think it's the ECU? hmm, I will run that by them now.
Oops, I forgot they ran it without the MAF. The boost gauge shouldn't have caused a huge short. I would think they would have tested the ECU, but who knows. They're gonna say "if the ECU was bad it wouldn't start" or something like that, which is crap. It could be corrupted somehow, partially fried, or I could be dead wrong. I've seen that before with other cars though. The ECU is $$$, so I'd make certain that it is not that. I would ask them a few times, and make them test it. And make them check the sensors Groceries suggested.
 

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Any chance it could be your MAF sensor as well? I would think they would have checked this already.This may explain why it gets worse when you change your intake and bov, however I don't think this would cause all that misfiring. Is the bov set to recirc or vta? What kind of intake did you have on there? I wonder if your ECU shit the bed...

that was my first thought too


coil packs are like spark plugs, you should always do them all, if one failed the others cant be far behind.

crank angle usualy works or it doesnt


with my nightmare of missing and 7mpg i ended up replaceing the coil packs,plugs,injectors,hpfp,lpfp and the ecu all in one day............the mileage was better but the missfire stayed untill i replaced the battery, my though was that the alt. wasnt suplying enuff voltage alone and a failing battery was to much drain on the system for the ignition to work properly......... or it was just something else to do with magic or something, at any rate my missing has been gone for over a year.
 

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Discussion Starter #11
Do you have any way to monitor spark advance or fuel parameters, OP?

Your jumping to a totally seperate circuit from spark to fuel. I don't think it'd be injectors. Misfire would be from a physical timing issue, sensor or plug/coil problem. Backfires could be from unignited charge mixture?
I unfortunately do not. If you are referring to a Dash-hawk or something of the sort, I do not have any of that. The only monitoring device I own is my boost gauge. The car doesn't backfire every time it does this, the backfiring is very rare, but I do hear a "popping type" of sound coming from the exhaust every once in a great while.
 

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I disagree about the position sensors. I mean, yeah they usually can leave you stranded. But, they can cause misfires on their way out. I just swapped a cam sensor out in a friends 2.5 Altima. He ran the car for two weeks with it working intermittently.
I didnt think the MAF was used in spark/ignition calculation. I thought it's openloop only for use in making fuel trim calculations...
Anyway, a way to monitor engine function would help.
 

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but the missfire stayed untill i replaced the battery, my though was that the alt. wasnt suplying enuff voltage alone and a failing battery was to much drain on the system for the ignition to work properly.........
Now that I read that, I just remembered that I've read that in at least two other threads on different forums. Forzda was saying something almost identical to what you said above. Their alternator was fine, but it was just a dying/dead battery I think. Good call!! OP definitely have the battery and alternator checked.

EDIT: Groceries, ignition timing is dictated by both load values and rpms. Fueling is also dictated by load and rpms for both CL, and OL/Part throttle. OL/WOT goes by rpms only.
 
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Mmm...I guess could be the batt. Can't believe there'd be the CCA to fire a cold motor, then not run it. But, it's a major part of the elec circuit, so it's of course worth checking...
 

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The FSM has quite a bit of detail on how to troubleshoot the Missfire codes WITHOUT swapping lots of parts. Sounds like your dealer tech may be a really cool guy, but not so smart on fixing your car....

Go back and ask to see the Factory Service Manual section on missfire diagnostics and see for yourself what he's supposed to be doing.
 

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The FSM has quite a bit of detail on how to troubleshoot the Missfire codes WITHOUT swapping lots of parts. Sounds like your dealer tech may be a really cool guy, but not so smart on fixing your car....

Go back and ask to see the Factory Service Manual section on missfire diagnostics and see for yourself what he's supposed to be doing.
Kinda what I was thinking...

Enlighten us!! Especially those of us who aren't blessed with a WSM. Lol!
 

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The FSM has quite a bit of detail on how to troubleshoot the Missfire codes WITHOUT swapping lots of parts. Sounds like your dealer tech may be a really cool guy, but not so smart on fixing your car....

Go back and ask to see the Factory Service Manual section on missfire diagnostics and see for yourself what he's supposed to be doing.
Pops-I'm glad you finally made an appearance! lol And bump for the only thing shaking on the forums today.
 

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Discussion Starter #19
The FSM has quite a bit of detail on how to troubleshoot the Missfire codes WITHOUT swapping lots of parts. Sounds like your dealer tech may be a really cool guy, but not so smart on fixing your car....

Go back and ask to see the Factory Service Manual section on missfire diagnostics and see for yourself what he's supposed to be doing.
I don't think it's so much him as it's the hotline. If it was his choice he would replace everything he wants to, but since it is going through warranty, he has to call up a hotline and go through their steps. Otherwise, I will be paying through my ass for parts that weren't approved by the hotline/warranty service.

What exactly should I ask them for?
 

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Discussion Starter #20
that was my first thought too


coil packs are like spark plugs, you should always do them all, if one failed the others cant be far behind.

crank angle usualy works or it doesnt


with my nightmare of missing and 7mpg i ended up replaceing the coil packs,plugs,injectors,hpfp,lpfp and the ecu all in one day............the mileage was better but the missfire stayed untill i replaced the battery, my though was that the alt. wasnt suplying enuff voltage alone and a failing battery was to much drain on the system for the ignition to work properly......... or it was just something else to do with magic or something, at any rate my missing has been gone for over a year.
Would you suggest replacing the Battery?
 
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