View Full Version : RB motors.. why do they hit fuel cut?
kurbn
07-08-2009, 10:48 AM
Was wondering what triggers a RB to hit fuel cut, my car has been hitting fuel cut alot recently and its only running 14psi - more in the morning when its cold, I have dropped the pressure down slightly and it seemed to stop but wont be sure til tomorrow morning.
just strange pressure would trigger it (especially only 14psi) as my last 32 ran 18psi no problem :S
is it pressure? cold air? mixtures?
Alt_F4
07-08-2009, 10:50 AM
Cold air = more hp = stock ecu shitting its pants and hitting boost cut
MikeS14
07-08-2009, 10:53 AM
Fuel cut is caused by the ECU seeing more air entering the engine than it was originally programmed to use. This likely corresponds with an injector duty cycle which is unsafe or unattainable. So basically fuel cut is caused by the AFM seeing too much air.
It probably happens more in the cold because cold air is more dense so even more air is getting into the engine.
Scradly
07-08-2009, 11:16 AM
Im pretty sure Rb20s dont have a fuel /boost cut.
Might have another problem ie: spark issue/ dead coil pack.
Silencio
07-08-2009, 11:18 AM
check spark plug gap, and move on from there
180SXTCY
07-08-2009, 11:19 AM
if u want a cheap way around it, get ya self a fuel cut defender. u just solder it into a few wires and removes the cut.
Easily removerd by moving the crankangle sensor a few mill with a chissel
yeahlow34
07-08-2009, 11:59 AM
Easily removerd by moving the crankangle sensor a few mill with a chissel
LOL!
kurbn
07-08-2009, 01:04 PM
sory but dont get it^
plugs are .7, were .8 but still did it then, so basically to fix it i need to get a nistune, is weird tho because my last 2 R32s never had this issue.
its definatly fuel cut, my ribs hurt, you get thrown forward, pump the pedal again and it keeps going until the next gear and blaa... even more of a sore chest
its not ur plugs bro, lower the boost. I had the same problem b4 i got my power fc, ur other rbs mite of been freaks.
d1_drifter
07-08-2009, 02:20 PM
Easily removerd by moving the crankangle sensor a few mill with a chissel
Ahh, the ol' CAS bash... Haha
kurbn
07-08-2009, 03:19 PM
its not ur plugs bro, lower the boost. I had the same problem b4 i got my power fc, ur other rbs mite of been freaks.
they were man, the motor on paper had 250rwhp but yet stayed hard on the bumper of a VL turbo that ran 12s... seeing you say its more the fact its because the AFM detects too much airflow perhaps the AFM I have is a clean one and reads correctly and my last AFM was not as good as I thought, as I have replaced the AFM as well last week and does it more now.
Pretty simple problem anyhow, tune her and she'l run like a dream.. wouldnt trade the 20 in my 32 for anything.
Im pretty sure Rb20s dont have a fuel /boost cut.
Might have another problem ie: spark issue/ dead coil pack.
x2
faulty afm maybe
R31 POWER
07-08-2009, 07:02 PM
Definitely a problem, no fuel cut with a 20.
Midnight
07-08-2009, 08:06 PM
Try Coilpacks, my 25 felt like it was fuel cutting but solved the problem by installing splitfire coils.
+1 to faulty afm.. had same problem only it got x20 worse
take it out and spray it with some MASSAIRFLOW cleaner $10 at supercheap..
if its still going get a new afm,
SimonR32
07-08-2009, 09:42 PM
dead coil packs...
which i have also posted in the last 5 topics you have made
kurbn
08-08-2009, 07:14 AM
if it was a coilpack wouldnt a cyl drop and just make it splutter?
Ahh, the ol' CAS bash... Haha
can someone explain this?
i take it it would in theory change the timing?
SimonR32
08-08-2009, 02:57 PM
if it was a coilpack wouldnt a cyl drop and just make it splutter?
if they are all fvcked... which they will be after you gave them a good watering the will all not have enough power to spark under boost
upgarage
08-08-2009, 03:06 PM
pretty sure they have backfire to cause arguil and break people up with their girlfriend
Brockas
08-08-2009, 03:08 PM
can someone explain this?
i take it it would in theory change the timing?
A method practiced by "Perths best tuner" to adjust base timing.
31-EVO
08-08-2009, 05:45 PM
if they are all fvcked... which they will be after you gave them a good watering the will all not have enough power to spark under boost
have you had this problem before Cerbera? you seem really convinced
Since turning the boost down a minor amount the problem has stopped
edit: my bad this is Bangn lol
DTM-031
20-08-2009, 10:56 AM
Definitely a problem, no fuel cut with a 20.
Got any cuts? Boost/fuel etc? I have the same issue on my RB20, lowering the boost fixes it, is worse on cold nights, violent cut etc. Only recently had the issue since the bigger turbo, but unsure whether it would be AFM has gotten dirtier or just the bigger turbo is maxxing out the AFM
Got any cuts? Boost/fuel etc? I have the same issue on my RB20, lowering the boost fixes it, is worse on cold nights, violent cut etc. Only recently had the issue since the bigger turbo, but unsure whether it would be AFM has gotten dirtier or just the bigger turbo is maxxing out the AFM
Its not the afm.. the bigger turbo is pushing more air and the engine management doesn't like it.
Coils and engine management...
DTM-031
21-08-2009, 09:03 AM
safc get around it or need to go full management?
Why do people insist on piggy backing SAFC's and FCD's, go full management, will save you a fortune in the long run when your motor doesnt go BANG.
Get a powerf FC for all of 1500 bucks, plug and play tuned for 300 and you'll never have to worry again...
DISTRBD
21-08-2009, 09:33 AM
Get a powerf FC for all of 1500 bucks, plug and play tuned for 300 and you'll never have to worry again...
Fuck 20 off and go 25 NEO :boink:
Skitzo
21-08-2009, 09:34 AM
haha, because full management is coin. People don't like seperating their pockets and coin.
then costs them a shit load more coin, they get emo slash wrists and stop playing with cars cause theyre broker than before...
cactus
21-08-2009, 11:54 AM
SAFC2 is awesome... whats the point of running a full management system on a cheap ass rb20 with minor turbo upgrade? I had SAFC2 running my rb20 with big turbo for a year, never missed a beat (and I thrashed this thing every second I drove it, because I'm tough), had an awesome tune, and ran ten times better than it did with stock ecu/turbo. Its simple, cheap and works a treat!
Alt_F4
21-08-2009, 12:22 PM
Retune the stock ecu for best (and cheapest) results.
Nistune it if you have the extra coin (cheaper in the long run)
kurbn
21-08-2009, 12:26 PM
I have used the SAFCII (with Azura?) and no complaints here, was a large difference in power delivery compared to stock management, imo its excellent bang for buck, however Andrew at hyperdrive allways told me to go for a nistune as its a safer unit to use.
il be going nistune this time for the extra power and less shit sitting up on my dash
Skitzo
21-08-2009, 12:36 PM
im in the process of downgrading from wolf to nistune. Hopefully nets good results.
kurbn
21-08-2009, 12:40 PM
im in the process of upgrading from wolf to nistune. Hopefully nets good results.
fixed.
lysdexia
21-08-2009, 12:42 PM
RB20s definitely do have a fuel cut, some people refer to it as a boost cut. with more boost obviously this put the load points into a different section of the map. if it goes off the map, it cuts. on a cold night, the air is obviously more dense, so it puts the point further up the map.
cefiro ECU does it much worse than R32 ecu too, has a smaller map (16x16 rather than 32x32 if memory serves).
nistune can sort it out.
rucker_
19-09-2009, 12:42 PM
At about what amount of boost would fuel cut usually occur with an rb20?
I know in my FC as soon as i went over 8-9 PSI it wanted to shit itself.
Car im looking at has Greddy FMIC and 3inch Catback (Suspect maybe 2.5 dump but havnt taken a closer look).
Would these mods boost it up enough to hit fuel cut?
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