high rpm breaking up

[truepinoy]

hi. ive searched quite a bit but haven't really found any good answers, and i was wondering if you guys can help. the car is a 1990 240sx ka24e with a t3 turbo at 12psi. i have tried gapping plugs down to .02 and .03 etc.. but it still breaks up..i have changed the wires and the coil is good. my fuel pressure is a little high, 52psi no vaccuum, could that be the problem?? to rich?.....thankyou

[Ter240sx]

maybe leaking valve cover? mine was and after i cleaned the spark plugs from the extra burning oil it no longer cut out when hitting boost

[nifares240]

sounds like you need a tune. you should upgrade your ignition to msd. this will make your spark bigger.

[truepinoy]

my plugs didnt have oil on them, my cover is leaking alittle but its not getting to the sparkplug...thanks though

sounds like you need a tune. you should upgrade your ignition to msd. this will make your spark bigger.

i have the msd blaster 2 coil..

[rioredstang]

I don't know much about ka'ts but what kind of tune do you have in the ECU? I have been trying to learn how to use a wide band to tune with. If you don't have one you can do like we did in the old days. Take it out on a stretch of road where you can run thru the gears till it starts to break up. Push the clutch in and cut the ignition off immediately. If you have a auto then put in neutral and shut ignition off. Pull over and pull the spark plugs out and look at them very carefully. If they are white colored then you are lean. If they are dark grey to black then you are rich. If they are a tan to light gray then I think you are close. It sounds like it is still a little lean on the big end of the rpm band.

[nifares240]

did you upgrade injectors and fuel pump?

[slidestyle69]

Be a little more specific here.

Did you just get the kit on and ran into this or has it been running fine and then randomly started doing this?

What are you tuned with?

injectors?

stock fuel pump?

[truepinoy]

did you upgrade injectors and fuel pump?

the injectors are 440cc or 470, i forgot. the fuel pump is a 255 walbro...stock fpr...

the kit was pieced together..i was running 7psi on an fmu, but then switched to 12psi with an emance tune..rather rich...

oh maxima maf in a blowthru setup on the cold pipe with adequate amounts of piping on both sides of the maf..

the sparkplugs are half white and half black..

[Chris28]

Change your spark plug wires. Sounds like what happened to me.

You also might want to invest in a better tune, or at least a wideband afr gauge. Emance tunes aren't known for their reliability.

[rioredstang]

If they are half white, half black, then you are over fueling in part of the rpm range. I would think it's leaning out and running the plug tips hot. You need to invest in a wide band or get a few friends and go together and buy one. You can then data log and see where your fuel curve is going.

[truepinoy]

wideband is next on the list for things to get...im still saving..