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Miss Rb20det

Mase

By Mase,
in Engines & Forced Induction

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Al Grand Master

Al

Posted
Posted

Boost cut?

Just a theory: When you are at a constant 5000rpm the turbo is well on boost, then the jab of the throttle causes the turbo to spike, engaging the ecu to activate the boost cut. Not sure if i am just spinning shit :lol:, but i have also felt that if i keep the revs at 4000rpm, in 2nd, then poke the throttle, the response is so much greater and the arse end steps out harder. I do not have any problems though, but my car is not exactly standard :(.

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limpus Mentor

limpus

Posted
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Isn't the proper term fuel cut?...and as to why the car might be missing...there could be several reasons...the plugs could be F##ked or the gap might be too big...when running higher boost...its always a good idea to have the plugs regapped to 0.8mm...i'd reckon this should be the first thing to check...good luck...

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Turbine Collaborator

Turbine

Posted
Posted

You may be hitting the fuel cut circuit in the ecu, just wtch your boost gauge and see whats happening without crashing :angry:

We had an R32RB20DET on dyno last week which kind of had the same problem. Ended up being ignition coils on 2 cylinders. They looked cooked around the sealed solid resin area. Check it out

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Turbine Collaborator

Turbine

Posted
Posted
Hey Turbine do you know where you can get your coils tested for free ???

You could do this yourself. Check the manual it should tell you how to test them. I dont run the standard nissan coils in my 20 so I cant help much their.

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Mase Mentor

Mase

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Sorry guys should have gave more info. I'm running bcpr6es NGK's which are gapped at 0.8 (be lucky to have done 1000klms on them) and i'm running F.E.T high capacity coil packs...

I'm thinking boost/fuel cut.... Just never came to my mind until someone mentioned it up there /\....

Gonna remove the boost T, and also going for a run with my mates air/fuel wideban meter to check the mixture this evening..

Only thing is, my wastegate runs 13psi stock, i installed the boost T wound all the way out to try and bring on boost sooner but keep the 13psi boost. I did think that it would prob creep to 14psi etc. I'll let you all know how i go anyway, many thanks for the ideas!!!

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Al Grand Master

Al

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Well i would think that it is not called fuel cut either, as the last thing a manufacturer would do is lean the fuel mixtures at high rpm.

ECU detects high boost level and cuts the ignition, so technically it is an ignition cut :lol: :)

Read the first post carefully:

When going through the gears normally my car boosts fine with no hiccups. But tonight i tried staying in high revs in 2nd at a constant rpm (lets say 5000rpm) then flooring it and the car started missing. It only does it when i do this?

Any ideas or suggestions?

Cheers

Jayson

Fault does not occur until he keeps the revs at a certain rpm, then pokes the throttle. If it was plugs or coils, the spark would break down when he is driving the car hard, not only when using this techneque.

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boot_it Enthusiast

boot_it

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Well i would think that it is not called fuel cut either, as the last thing a manufacturer would do is lean the fuel mixtures at high rpm. 

ECU detects high boost level and cuts the ignition, so technically it is an ignition cut :lol: :)

Read the first post carefully:

Fault does not occur until he keeps the revs at a certain rpm, then pokes the throttle.  If it was plugs or coils, the spark would break down when he is driving the car hard, not only when using this techneque.

they dont lean the engine fuel mixtures out at hi rpm the ecu cuts the power to the injectors so there is no fuel to burn that why its called fuel cut

are u sure its not pre ignition

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Mase Mentor

Mase

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Posted (edited)

like someone above mentioned, it only happens when holding the car in high revs then stepping on it.. This causes a massive surge of boost/fuel as the turbo is in it's prime ready to boost and it was casuing boost/fuel/ignition cut or whatever it is.

Basically... removed the bleed valve, problem sorted now.. WHich is farken awesome as now i can drift it at Sunday's drift day!!! yey

But with a bit less power ;)

Thanks for all your info and advice

Edited by Mase
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