I have a 2017 Mazda 2.5 that keeps throwing a flashing CEL and the codes keep coming back as a random misfire. I have already changed the spark plugs, ign coils, map sensor and checked the intake ports for carbon build up, and did a trans filter service (not sure if relevant or not). It mostly happens when the engine is warm, it revs up to 40 mph and will start to misfire and flashes the CEL and the puts the engine in limp mode. I've noticed that it starts doing this around 2500 RPM also. it happens mostly shifting in and out of 4th gear. Not sure what else to do or check.
did a trans filter service (not sure if relevant or not)
not even a little bit.
You need to stop guessing and start looking at data. Start with a cylinder misfire count and fuel trims.
Since it happens at higher RPM, I would also suspect restricted exhaust.
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@imperator Cant look at data, I don't have that kind of tool. I'm just some guy who has taken it two different mechanics and they both said ign coils. I replaced the ign coils after the first mechanic recommendation, and had the second one say the same thing and Im not trying to throw any more money at diag fees for someone who pops the hood and says you need coils
well the diag fees will pay off if the mechanic actually uses data to make a diagnosis, and not just guess which parts to throw at it next. Replacing random parts is definitely flushing money down the toilet.
I have already changed the spark plugs, ign coils, map sensor
Did those test bad or was this just guessing?
did a trans filter service (not sure if relevant or not).
Not relevant to misfires but good maintenance to change transmission fluid and filter regularly unless neglected for a long time.
Not sure what else to do or check.
Any codes other than P030x? What are the actual codes? Any big vacuum leaks? Anything off kilter in live or freeze-frame data?
@chucktobias So I have gotten P0301,2,3,4 at some points in time, as of now its just P0300, not sure to to get live or freeze frame data
not sure to to get live or freeze frame data
Check your scan tool manual. These days even most inexpensive scan tools can access the data, however there are still a few around that can only read codes.
Cant look at data, I don't have that kind of tool.
You can get that kind of tool for $50 or less, for example:
https://www.amazon.com/CGSULIT-SC301-Diagnostic-Vehicles-Emission/dp/B095WMX6B8
A Project Farm test of inexpensive scan tools can be found here:
https://www.youtube.com/watch?v=UR9RLgfV-qM
You need to have access to data to effectively troubleshoot modern cars.
Out of curiosity, did you change the plugs before or after the problem started and did you use OEM plugs? A very good mechanic that I know told me the other day that using plugs other than the exact type that came from the factory often causes the computer to get confused and all kinds of codes start tripping, even if the replacement plugs are supposedly suitable for the vehicle.
Good luck.
