Jump to content
SAU Community

Boost Cut?

G-reddy

By G-reddy,
in Engines & Forced Induction

 Share

Recommended Posts

G-reddy Enthusiast

G-reddy

Posted
Posted

so on my 2am trip home from work i was wondering why at around 5k rpm the car starts to lose power and why 'pop's are coming from the exhaust..

pondering away trying to keep myself awake at the wheel i came to the (guessed) conclusion that the reason may come down to the factory boost cut..

my reason for thinking this is happening at around that rpm is because of the larger volume of air needing to be pushed through due to fmic and the fact that my exhaust is 3 1/2" or 4.. not 100% sure, but shes a big bugger from the turbo-back..

how off the mark am i?

if it is this, how can it be rectified?

ps, S1 R33 gtst if it helps..

cheers, mac

Link to comment
Share on other sites
PsYLoR Collaborator

PsYLoR

Posted
Posted

Could be your Coils, If stuffed they could cause missfire around the 4500-5000 rpm mark.

If there still stock one's, over time they develop hairline cracks which divert the spark from reaching the spark plugs.

Just a thought. >_<

Link to comment
Share on other sites
TiTAN Grand Master

TiTAN

Posted
Posted
so on my 2am trip home from work i was wondering why at around 5k rpm the car starts to lose power and why 'pop's are coming from the exhaust..

car stops accelerating suddenly followed by a few loud pops and bangs from the exhaust and then continues accelerating normaly from ~5500-7000?

Link to comment
Share on other sites
G-reddy Enthusiast

G-reddy

Posted
  • Author
Posted
car stops accelerating suddenly followed by a few loud pops and bangs from the exhaust and then continues accelerating normaly from ~5500-7000?

neg. no big bangs or anything, just a heap of little pops and no power.. thus why i asked if it was boost cut because its like engine is being starved of air.. i was told by a somewhat informative source that it was boost cut and that it can only really be fixed with an a/m ecu+tune.. will avcr or equivellent be sufficient or should i be looking into a haltec or similar?

Link to comment
Share on other sites
SXC-R34 Collaborator

SXC-R34

Posted
Posted
neg. no big bangs or anything, just a heap of little pops and no power.. thus why i asked if it was boost cut because its like engine is being starved of air.. i was told by a somewhat informative source that it was boost cut and that it can only really be fixed with an a/m ecu+tune.. will avcr or equivellent be sufficient or should i be looking into a haltec or similar?

I had a similar problem, it's all gone now though after installing a couple of mods and tuning it on Apexi's Power FC

Link to comment
Share on other sites
35NIK Enthusiast

35NIK

Posted
Posted

I got the same problem at 5000rpm my car pops & stops gainning power then 6000rpm it jumps back in to power till redline. I assumed it was my coilpacks, But I just dont have the spare $600 at the momment, incase thats not my problem. I have been doing some research of bikirom daughter ecu board for the R34 which is $550 fitted with the same capabilitys as a power fc. So im going to try that first then replace the coils.

Link to comment
Share on other sites
JonnoHR31 Grand Master

JonnoHR31

Posted
Posted
neg. no big bangs or anything, just a heap of little pops and no power.. thus why i asked if it was boost cut because its like engine is being starved of air.. i was told by a somewhat informative source that it was boost cut and that it can only really be fixed with an a/m ecu+tune.. will avcr or equivellent be sufficient or should i be looking into a haltec or similar?

spark breaking down, tape up or silicone your coils and buy some new plugs and gap them down

Link to comment
Share on other sites
TiTAN Grand Master

TiTAN

Posted
Posted
I got the same problem at 5000rpm my car pops & stops gainning power then 6000rpm it jumps back in to power till redline. I assumed it was my coilpacks, But I just dont have the spare $600 at the momment, incase thats not my problem. I have been doing some research of bikirom daughter ecu board for the R34 which is $550 fitted with the same capabilitys as a power fc. So im going to try that first then replace the coils.

Turn the boost down, mine used to do that on the stock ECU at anything over 12psi but never did it at 11psi or less.

Link to comment
Share on other sites
35NIK Enthusiast

35NIK

Posted
Posted
Turn the boost down, mine used to do that on the stock ECU at anything over 12psi but never did it at 11psi or less.

im only running 10psi, or sometimes it creeps to 12-13psi

Link to comment
Share on other sites
SiR_RB Grand Master

SiR_RB

Posted
Posted

i got the same problem, and it just started few nights ago out of no where

i put silicone on the coilpacks (hi temp Loctite one) but its still there - between 4500 and 5500 after that its fine

my NGk iridiums r about 60,000kms old so im putting new copper ones in tomorow gapped to 0.8mm and giv it ago, hopefuly its just my plugs that need replacing and not the coil packs

Link to comment
Share on other sites
R34GTFOUR Mentor

R34GTFOUR

Posted
Posted

Its impossible to tell over the net, theres a few common things that can cause the exact thing you're talking about. But from personal experience, my bro had a r33 gtst (basically stock) and it behaved like what you are talking about.

We started with the basics. new plugs, regapped then to .7mm, new fuel filter, new fuel pump, new coil pack harness (had a spare) etc...

Still had the problem, it would splutter and pop from about 4800rpm through to redline.

Bought a powerfc, BANG fixed. Never had another problem. Instant impovement.

Best mod on the car from date was the FC.

My 2 cents

Link to comment
Share on other sites
Driftin~Davo Enthusiast

Driftin~Davo

Posted
Posted
Its impossible to tell over the net, theres a few common things that can cause the exact thing you're talking about. But from personal experience, my bro had a r33 gtst (basically stock) and it behaved like what you are talking about.

We started with the basics. new plugs, regapped then to .7mm, new fuel filter, new fuel pump, new coil pack harness (had a spare) etc...

Still had the problem, it would splutter and pop from about 4800rpm through to redline.

Bought a powerfc, BANG fixed. Never had another problem. Instant impovement.

Best mod on the car from date was the FC.

My 2 cents

Power FC's FTW. But if u dont have 1k laying in ya wallet its good to get ya standard ecu running 100%.

I have the exact same problem wif a series 2 25 in a cef. I've regaped plugs to .8mm, taped up all coil packs, made sure i had fuel. And it still breaks down at 4-5k making no power and wont rev any further. I'm using a RB20 actuator and not seeing more then 7psi. The only freakn thing i can think off is maybe my AFM is dieing slowly so i'm gonna try n borrow a mates 2moz and hopfully that helps. btw do RB25 afms fail often?

Link to comment
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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • GTSBoy
      Fake ARP bolts?

      By GTSBoy · Posted

      Meh. I "see" a typo above, that should have been "sell".
    • joshuaho96
      Nismo copper mix twin “pull” pedal height engagement

      By joshuaho96 · Posted

      The clutch pedal has a procedure for adjustment. This can only be done after you are 100% sure the system is absolutely free of air bubbles. You must bleed the clutch master cylinder first, then the "separation pipe" which is the clutch damper line, then the operating cylinder as detailed in the service manual. Also, you must fully depress the clutch pedal between shifts. Just because you can't feel it grabbing does not mean the input shaft is truly decoupled from the crank. At high RPM clutch plates are vibrating and moving around, you need to give it the best possible chance of success. On the BCNR33 Nissan revises these adjustment procedures slightly but not by much: I would be careful with trying to play games with these adjustments. As for the Nismo operating cylinder they say a lot of things. In practice the twin plate clutch needs less movement on the clutch fork to disengage because the whole stackup of the flywheel + friction plates + pressure plate is much taller. Personally if you find that the clutch still disengages too high at the top of the travel I would try the Nismo operating cylinder. Make sure to follow the air bleed procedures. 
    • 25RBGT
      Got this r31 silhouette flood car to rebuild.

      By 25RBGT · Posted

      Thank you for the links. I’m going to go with the 6pin plug you used. next step is rust treating re painting dash support bar and steering column then the 6pin cradle plug when it arrives in the mail.
    • soviet_merlin
      Nismo copper mix twin “pull” pedal height engagement

      By soviet_merlin · Posted

      I don't how much the car makes a difference or whether it is just a question of gearbox and clutch. On mine it's fine. Pull type Nismo coppermix twin (standard, not competition) on the 5 speed in my Stagea. OEM slave cylinder. Bite point is a few cm off the very bottom of the pedal. Clutch pedal all the way down to put in gear, and when heading off at the lights, there's a tiny bit of nothing and then it starts biting. And fully engaged before the pedal is all the way released. There's a bit of play at the top where the pedal does nothing anymore. Are you in Australia @ck_chino? If you are set on using a Nismo slave cylinder I have one new-in-box at home. Ordered it together with the clutch but didn't get it fitted. We can work something out if you want it
    • Butters
      Nismo copper mix twin “pull” pedal height engagement

      By Butters · Posted

      I am using a pull nismo coppermix twin in an r34 getrag box, had both the standard slave and  then the nismo one. Adjusted pedal to get bite point how I wanted , it is on the higher side, but would fully disengage past half way down.  I also read that the nismo slave won't work but I had no issues with the stroke, might become one later as clutch wears but 2+ years of happy motoring so far.  Take the above as one input only, specially as my setup is a bit unique in that I am using an S15 clutch master , cefiro clutch pedal, custom braided clutch line. Lots of variables at play. 
×
×
  • Create New...