Boost Cut?

[G-reddy]

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

[PsYLoR]

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.

[G-reddy]

i was led to believe that coil failure was apparent at around 6-7k rpm all the way to redline?

[bubba]

I had issues about 4-5000rpm due to degraded coil loom.

[TiTAN]

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?

[G-reddy]

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?

[SXC-R34]

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

[35NIK]

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.

[JonnoHR31]

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

[TiTAN]

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.

[35NIK]

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

[SiR_RB]

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

[R34GTFOUR]

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

[Driftin~Davo]

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?