Rb20 Missing At High Revs

[djay]

hey guys i really need some help sourcing this problem becuase i have now run out of ideas.

rb20det

boche 044

standard injectors

kkr430

turbo tech 16 psi

microtech ecu

fmic

3" exhuast

new copper plugs gapped .8

ill start from the begining, when my car first started miss firing i found out that the fuel filter was block full of brown shit and the tank had water in it, i put a new filter in and cleaned out the tank and put injector cleaner with a clean full tank of fuel.

it was still miss firing after i used that tank of fuel.

so i bought some new plugs and i borrowed my mates standard injectors and coilpacks which i new were fine, installed plugs, injectors, coilpacks and cleaned the fuel rail because there was a little bit of brown gunk which was clean up any way it was still miss firing at high revs.

i have noticed if i dont hold the accelerater flat it doesnt play up.

[scotty nm35]

Did you change the fuel filter again? I would be cleaning the lines and tank completely then drying the lines with compressed air.

The injectors have a filter in the rail end, perhaps these are blocked? Don't keep stomping on it to test, its probably running lean.

[Kane_R32]

I'd try lower the boost back to waste gate pressure if possible. The lower the better as combustion pressures will be alot lower. Then see if it continues.

Have you done a compression test?

[djay]

yea i replaced the filter again, ill take the fuel rail out and give it a good clean and look over. is the fliter in the rail in each injecter slot?

cant really lower boost can i ? its tuned to this psi.? but ill also try a compression test.

[FordyR31]

My fuel pump was flowing less than it should causing it to run lean. Maybe have someone look at it on a dyno. Maybe running too lean causing the miss.

Edited July 9, 2012 by FordyR31

[StevenCJR31]

yea i replaced the filter again, ill take the fuel rail out and give it a good clean and look over. is the fliter in the rail in each injecter slot?

cant really lower boost can i ? its tuned to this psi.? but ill also try a compression test.

there is a mesh screen at the tail of each injector, the only way to clean the injector and the screen correctly is to backflush OR you can buy new screens but they can be a bitch to change

[Kane_R32]

Yes you can run lower, just remove the turbotech and place a vacuum line direct from the boost source to wastegate.

+1 with checking fuel pump

[djay]

ok so i found out why there was heaps of water in my tank, the fuel tank breather was facing behind the back wheel so when it was raining the tank filled up with water.

so i pulled the tank out and cleaned it properly and blew the fuel lines out and the fuel rail, and replaced the fuel filter and relocted the fuel tank breather line. after all this done it definatly went better but is still missing up at high rpm,

bought new ngk copper plugs, gapped to .8 and also tried running lower boost still missing up high, is there any way of testing the fuel pump myself or easier to to get it on a dyno?

[FordyR31]

Just hook up a fuel pressure guage to ur lines after the filter and before the rail and take it for a little drive and see what its doing.... Someone here will know what pressure it should be at idle and through the revs etc. Also depending on what pump u can flow test it aswell to see if its up to scratch. Failing that go to a dyno day.... 50 bucks and the tuner will give u an idea of what may b wrong.

Edited July 20, 2012 by FordyR31

[djay]

ok i decided to gap the plugs to .7 from .8 and now it doesnt missfire at high rpm, so happy and suprised that 0.1mm would make such a difference.

thanks for all the help guys

cheers.

[GH05T]

So lucky. I spent ages and lots of $$$ chasing my misfire. Gotta be happy

Edited July 22, 2012 by GH05T

[GTSBoy]

Splitfires are a better option to closing plugs.