Sr20det red top issues

[Banzaidrift]

I have a 1990 180sx, was originally a ca18det car, swapped in a red top sr. The car sputtered and spit at first would break up. I re did the timing and reset my cas. Fixed it mainly, now it pulls hard till 5000rpm and from there on it struggles/spits a bit and barely makes it to 7000rpm in 2nd gear so on. I have changed the ecu, coil packs, re did cas/ engine timing, changed/ cleaned maf and changed/ re-gaped my plugs. Cylinder number 4's plug was black when I pulled the plugs. Others were burning normal. Have to check for boost leak still. But according to my boost gauge I'm always at 7psi when under full boost. Motor is stock, freshly rebuilt with 2200km on it. Anybody have an idea what it might be?

[Banzaidrift]

Checked all of my clamps and tightened them. Changed coil pack on cylinder #4, still the same thing happening from 5500rpm on. Also checked ecu and it's not throwing any codes.

[ultimateirving]

Check knock sensor, and make sure its properly installed.

[Banzaidrift]

I will do that for sure.

[Banzaidrift]

It has a light miss under light throttle and higher up. I move the cas it gets worse I move it back it starts to go away. I'm confused. I re timed it, changed ecu, changed cas, and changed igniter. It pulls hard but still breaks up a bit in the top end. And my ecu has no codes.

[Banzaidrift]

Also has a miss at idle, changed coil packs and same thing.

[ultimateirving]

Also has a miss at idle, changed coil packs and same thing.

Miss at idle is a symptom of something sinister. Check your ground set up. Do you have a front mount set up? how is your wiring and is the battery strapped down.

[Banzaidrift]

I do have fmic, I'll check my wiring again, and my battery is in a Taylor battery box in the hatch.

[Banzaidrift]

I have a few extra grounds off the motor. My friend did recently hook up the booster cables backwards. Blew my ecu, cas and igniter.

[Banzaidrift]

Well I fell like an idiot. But found out my intercooler hit my frame awhile back and broke. So I had a boost leak. Also a bad tps, and my maf was really dirty.

[240SilviaX]

What fuel pump do you have? 255? fuel filter new or clogged? Injectors? get them tested?