Jump to content
SAU Community

Recommended Posts

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 :(.

Link to comment
https://www.sau.com.au/forums/topic/98357-miss-rb20det/#findComment-1787171
Share on other sites

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...

Link to comment
https://www.sau.com.au/forums/topic/98357-miss-rb20det/#findComment-1787709
Share on other sites

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

Link to comment
https://www.sau.com.au/forums/topic/98357-miss-rb20det/#findComment-1788070
Share on other sites

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.

Link to comment
https://www.sau.com.au/forums/topic/98357-miss-rb20det/#findComment-1788706
Share on other sites

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!!!

Link to comment
https://www.sau.com.au/forums/topic/98357-miss-rb20det/#findComment-1788954
Share on other sites

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.

Link to comment
https://www.sau.com.au/forums/topic/98357-miss-rb20det/#findComment-1790156
Share on other sites

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

Link to comment
https://www.sau.com.au/forums/topic/98357-miss-rb20det/#findComment-1790327
Share on other sites

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
Link to comment
https://www.sau.com.au/forums/topic/98357-miss-rb20det/#findComment-1791445
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • I’ve got one on mine and it’s fine, 
    • No, you don't want to plug the vacuum line, as that will turn that side of the booster into an air spring and probably make it feel worse. I'm not saying that the GTR master itself doesn't need a booster. I haven't paid attention to the GTR one to know what size it is cf the non-GTR ones. But when you think about it - they have to do the same job, which is to move a little slave piston a few mm to do what it is supposed to do, and that final action is the same on all the cars. So, it is very unlikely that the GTR MC is any different than the others, because it has the same pedal stroke and the same output requirement. The booster just makes it feel easier. I'd suggest you probably have an actual hydraulic problem. It's totally common on these old shitboxes.
    • Ye, in terms of bolting up the "Conversion" from a GT to a GTT is effectively "Use GTT parts for everything" Except the subframe itself, because you won't want a HICAS/4WS subframe. Remember your ABS system will be different too, thanks to GT being the S15 3 sensor system, instead of the R34 4 sensor system for wheel speed. I do not know how people get this to work given R34 diffs do not have a provision for an ABS sensor (they are on the tone wheels of the axles). I assume***** people use S15 gear/R34NA forever when they realize this - Or they convert it to a rear diff/axles that are R33 style which I presume has the singular speed sensor on the diff itself, but then you have to wire it all in and...and... and...
    • Foreshadowing was never so easy.
    • The ones in brackets are the first stages of tightening. I usually aim for the middle of the range. They give a range because it's actually not that critical to hit exactly the right bolt tension. Enough is enough, and too much is too much, and the range given is inside that range. Half of the bolts in the suspension are problematic for putting a torque wrench on anyway, so just get done up to mechanic tight  and spanner checked a week later.
×
×
  • Create New...