2014 Sport model, having a hard time figuring out what is going on. About 4-5 years ago I got a P0302. It was an ignition coil, bought one at autozone and it ran golden. 2 years after that same code, bought a oreilleys one, ran perfect. I am now here with what started as P0302. I also replaced all spark plugs the first time.

Bought a new coil, put it on but it drives rough.
Bought another coil thinking it was faulty, rough. Swapped an old coil to the 2nd cylinder and it was slightly better but rough.
New code is P0304 even with new and old coils. This took multiple swaps, it didnt change to P0304 right away, and even with the original that was fine still has that error even with reset.

the weird thing is it drives fine with light acceleration. Hills will have the car shaking minimally, flooring it puts it into limp mode. At one point the check engine light was off but it still shook when using too much gas. It doesn’t do this in park, i can floor it with no problems. Unplugging each coil with the engine running provides the same amount of engine shaking. I was going to look at spark plugs but theyre newer and the code actually moved for the first time.

if anybody at all has insight, I will highly appreciate it. Thanks!

 

STOP swapping and replacing parts before you FIRST confirm that they are faulty. What you have now effectively done is mixed things up so bad I cant figure out if you returned everything back to it original place and actually install everything correctly? Just because YOU THINK the coils and positioned properly and that the spark plug to you seems to be connected to the coil properly is not what I am reading.
Reading what you posted tells me that you have a coil, connector or spark plug issue either a part that is not to specification or not making proper connections.
As for the codes DTC.... START OVER!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Note the DTC/codes in the active file of the ECU. Go to pending and not the DTCs. Then go to your monitors and not which are NOT in the state of readiness.
Clear the DTC and reset the monitors. Then after the engine has cooled overnight start the engine and as soon as the check engine light appears STOP the MAZDA and get the newest DTC. Note it and continue your drive for at least 15-30 minutes. Then recheck for any new DTCs. Also check the monitors again and see which are not in state of readiness.
Now compare your information . Or post up the new information ?

 

Welcome to the forum

 

To all DIY
The basic steps in any OBDII or CANbus system is NEVER replace part randomly without first confirming that they are or have failed. Almost always doing so creates additional problem that now need to be addressed on top of the original problem making to solution harder and more costly to resolve

 

I put everything back in its original spot. It was in need of a new coil though, this is the 3rd time it popped up and the car was drivable with only replacing the 2nd cylinder. It was confirmed failed and the replacement of that coil put the engine check light away. The light was gone for 2 days before I purposely floored it up a hill to see if it went into limp mode. The only issue this time is even though its drivable, it shakes when accelerating too much. If I lightly apply gas I can get around perfectly fine with no issue. Didnt know if this could be a newer issue or not.

 

This means you were only running on 3 cylinders. At least how you are explaining it?
How was that confirmed failed. Either your Mazda was on a oscilloscope and there was NO WAVE PATTERN (not liekly) scope a Dignostice scanner useing some of its programing showed low voltage or no output signal trace?

A misconception among DIY is they assume that if a check engine light shuts off the problem was resolved. Thats not necessarily how it works. That why you need to look in the ECU permanent DTC file as well the monitors state of readiness.

The worst procedure is going to WOT (wide open throttle) to try to generate a DTC or problem before properly confirming that you first corrected the problem. Just because you failed to cause a DTC does not mean the problem was corrected. However, by your DIY method you may have simply by way of all the extra steps temporarily solved you problem. I say this because of your posted event information since you first state having the problem.


When replacing a coil pack/plugon coil the boot much be examined cleaned and a small dab of dilelectric grease placed on the edge of the boot to insure proper alignment of the inner sping that attaches to the terminal of the spark plug. If the alignent is not done correctly you can get DTC as well as cause a coil to fail at some point. The coils have a mortality rate that if they work in the first 8 hours of new operation, they WILL go their engineered lifespan with no issues.


The shaking from acceleration irregularities may still and I am going out on the limb which I normally DONT DO and GUESS that you still have an ignition problem unresolved? I think in the next few days you will see the DTC again(another GUESS)


ASE

 

Both times in the past when the coil failed, the car shook like a rocket ship and I was forced to pull over. The car would move about 2mph and was shot. The only fix was the coil replacement. Same exact thing this time, putting that same old coil in makes the car stop moving at all, except the newer coils aren’t completely fixing it this time. If you're telling me that coil is fine, please tell me what else to try as im stuck. All I know is the new coil lets me go 80 on a highway as apposed to 2mph in my driveway.

 

Time for a correctly done compression test

 

I wish you had gotten a concrete answer on what this misfire was from. I have the same year Mazda with the same problems. All coils have now been replaced as well as spark plugs but car still is accelerating badly up hills and will randomly go in limp mode if pushed too hard. Check engine light comes on occasionally and reads code p0303 misfire in cylinder 3. But if I clear the code it doesn’t come back for a few weeks.

 

Ok, you guys did coils and spark plugs. Hmmm...did you guys check injectors if it's clogged or in working order? Buying Coils from Autozone is a NO,NO! you always want the original.