Help with rfi misfire?

Single cell dip is back. I can't find any info anywhere that helps. High rpm (above 4500) it misfires. Shows hpfp pressure drops just one cell in the data log. Justin at freaktune says misfire . 2nd set of new plugs gapped to .027. Car runs fine otherwise.. maybe a pin hole in a intercooler boot? Need to find a 3.5" plug for new intake to boost leak test.
 
from like 1700 to 7 or 800 and it breaks up and backfires. new plugs , new hpfp new autotech internals look good cleaned .. new in tank pump. ive had this intermitenty for like a year. i get it cleared up then a few months later its back.
 
Justin made it seem like its actually a misfire causing my fuel pressure sensor to show a dip in fuel pressure but its actually a misfire. RFI
 
everything has been tested or gone through fuel wise. so im stuck thinking either a coil pack breaking down or a boost leak possibly? but it only happens at wot high boost.
 
a friend of mine is a mechanic. he put all the info into a program and it came up with upstream O2 sensor, intake valves need cleaned and or faulty injector. anyone had same issue ? id think it would have messed up stft and or messy idol if it were injector or intake valves.. idles fine and drives fine. 26mpg ish.
 
Not real sure how a failed spark event would result in 1000 PSI drop at the rail, esp since the injector should be closed before the spark happens. In fact I'm nearly certain the ECU is set up so it WON'T spark during fuel spray events.
 
they way i took what justin said, the pressure isnt really dipping? or the computer is cutting fuel because of the misfire? idk. does anyone have any experience with this happening with a faulty injector or gummed valves? it idles great. and gets good mpg. runs and drives great under normal conditions.
 
Plug gap, plug temp, etc usually resolves misfire issues.
Usually, the misfiring of a plug doesn't cause the ECU to dump fuel pressure, in my experience. Maybe second gens are different though.

Under load, I have seen where the HPFP internals not cycling properly can cause similar issues (experienced it myself where it will just drop pressure for no reason, but this usually happens whenever, not only at WOT).
 
i had a hotspot on my old internals and they were recently warrantied. had this issue before and after. idk what else to do. in my mind i feel like it has to be coil packs. lol ive never changed them. and when i stretched the spring a few weeks ago the issue went away. tightened a couple clamps a little more, and put a ferrite choke on my coilpacks and rail sensor. and it didnt miss anymore.
 
He said that a 1 cell dip can't be something mechanical it has to be electrical. Rfi last time it was a plug. I cnt buy plugs every 1000 miles.. and that didn't solve the issue. Lol
 
Guess ill dig into this and see what info I can find on the ckts.. and where they land in the pcm. I remember I bought a sensor so.e1 kn here gave me the part number but it was only a 90bar sensor and wouldn't read over like 1200psi. I have to order a 140 bar sensor from finjector
 
No, you need an OEM Mazda one. MUST be the same part; lots of places sell "OEM" parts that don't work properly, like o2 sensors as a good example. Sounds weird, but maybe a junkyard has one.
 
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