2014 Mazda 6 GT -108K miles - Had a P0300 $07e8 Multi Cylinder Misfire Detected. I changed the spark plugs, and put some Heet Dry gas in tank. Also checked wires for cracks etc. Erased the code and it came back a week later. There are absolutely no symptoms at idle, or when accelerating. The car starts and runs great. I am not sure of the next troubleshooting step. Maybe purchase 4 ignition coils from Rockauto. Maybe see if the dealer has a more precise way to diagnose the problem.

I would appreciate any help on this.

Thanks

 

A PO300 is a generic DTC that could relate to almost anything that runs the engine. When you "cleared" the code all your really likely did was to turn off the check engine light. Had you look at your monitors you would have seen that they were NOT in state of ready and that your problem was still there.

 

The dealers factory scan tool can read a miss-fire counter of individual cylinders.

 

Callisto, Grim_Reaper, Thanks for the replies. It appears my problem is gone. The check engine light has been off for a bout a week now, fingers crossed. I'm assuming the original P0300 was corrected by the spark plugs. Not 100% sure.

To summarize;
1. Replaced spark plugs with NGKs.
2. Heet Dry Gas.
3. Gumout fuel injector cleaner.

Thanks Again

 

The P0300 code came back yesterday, on 5/21, it was off for almost 2 weeks. Is the next step, go to the dealer for a diagnostic, or to change ignition coils? I'm open to any other options. Thanks

 

You do not start changing random p[arts unless you tested each part and verified, they failed. Rep[lacing untested parts could add more problems to the insisting unresolved one.
As i posted that DTC is generic and could be caused by almost anything. Theree is no guessing unless you are going to replace about couple dozen parts and hope you get the right part. Your DTC returned because it was in the ECU pending file and after several engine cycles the problem reported unresolved and the engine check light and DTC returned. That is also why many misunderstand that when you clear a DTC/CODE that simply removes the check engine light but does not remove it from the pending area of the ECU. Re setting the Monitors will do the same result but sometimes will indicate the DTC .engine check light quicker if the problem was not corrected. Speaking of monitors, they will give a good clue where to start the tree of elimination parts checking knowing what Emission area are not in state of ready.

Bottom line if you are r4eading this and going WT*(f) then you need to have a experienced Dianostic technician look at your Mazda.

 

Still working on P0300. Using a MOTOPOWER scanner. Have an output for Freeze Frame for the P0300.

If anyone sees anything significant in this data, that would indicate a cause for the P0300, please respond. Thanks

DTCFRZF P0300
Fuelsys1 CL
Fuelsys2 N/A
Load_PCT(%) 82.0
ETC(C) 21
SHRFT1 (%) -3.9
LONGFT1 (%) 2.3
MAP (kPa) 78
RPM (/min) 1407
VSS (km/h) 0
SPARKADV (*) -20
LAT (C) 17
MAF (g/s) 22.88
TP(%) 25.1
RUNTM(sec) 14
EVAP_PCI (%) 0.0
FLI (%) 73.3
WARM_UPS 23
CLR_DIST (km) 1093
EVAP_VP (Pa) 20
BAR0 (kPa) 97
CATEMP11 (C) 167.70
VPWR (V) 13.970
LOAD_ABS (%) 69
EQ_RAT 1.003
TP_R (%) 15.7
AAT (C) 17
TP_B (%) 25.1
APP_D (%) 15.3
APP_E (%) 7.8
TAC_PCI (%) 19.2

 

Where are you Ho2 voltages and also CAT/F
Those others all look ok

 

My cheap scanner doesn't appear to have those metrics. I think I need to call a Mazda shop to get a diagnostic run.

 

Just checked trouble codes, I have a P0301, cylinder 1 misfire. Would you recommend swapping coils between cylinder 1 and 2 with this new information, or is there a better way to troubleshoot this code?