sr20 misfire

[sr vegas 240]

Car is 89 with s14 sr20 European spec
Mods
Fmic
Intake
Turbo back exhaust
Boost at 15
walbro fuel pump
check engine light is flashing but when I check for fault it gives me code 55 which means no faults.

It has slight misfire on wide open throttle in 1st and 2nd gear more in 1st than 2nd at around 5k rpm.
I had boost leaks before that I fixed and it ran perfect untl now
I put a new fuel filter new oem plugs gaped to oem spec.
I put a new o2 sensor that kind of made it better for a week or so than back to misfiring. I drive the car one a week sometime once a month. I have a drift event coming up soon need to get it fixed.

[Kingtal0n]

could be breaking up lean, melting your piston. What does the wideband say.

You DO have a wideband, yes?

[sr vegas 240]

I don't have a wideband. It only does it for a split second and boosts fine to redline. Why would it be burning a hole in my piston?

[daryl337]

overboost on a stock tune.


Turbo-back exhaust without a proper boost controller can result in boost creep.

[sr vegas 240]

My fault I should of mentioned it does it on any boost stock to 15psi

[sr vegas 240]

Went trough the entire event without any issues 12 psi I will be getting a wide band soon

[sr vegas 240]

I should of wrote the from beginning but forgot the misfire was way worse I'd be on the throttle flooring it and if would fall flat on its face and go again. Than I replaced the spark plugs and fixed it completely than few months later not even 500 on the plugs and it's the way I described in 1st post