G
Guest
Unregistered
It just cuts like ur power has been cut and u go into shock and quickly release ur foot that instant and then ur back in action ...
Boost Cut - what causes it?
- Thread starter naughtika
- Start date
naughtika
OzVR4 Stalker
- Thread starter
- #22
err... sorry fellas.. i'm stupid.. when I took of the MBC, I have just gotten up.. and in order for me to take it off.. i had to disconnect of the plugs.. once I had the MBC off.. I forgot to re-plugin the wire plug 
see pic below - plug is circled in yellow..
what does that connector do? cause when I drove it earlier.. engine was running fine.. but once on boost I was getting that engine hesitation..
see pic below - plug is circled in yellow..
what does that connector do? cause when I drove it earlier.. engine was running fine.. but once on boost I was getting that engine hesitation..
Fred
Leaving Skid Marks
it looks to be the throttle position sensor, tells ecu how far the throttle is open....oh and whered u get your hard pipes from....(wants some)
naughtika
OzVR4 Stalker
- Thread starter
- #26
hey fellas.. thought i've liven this up..
I HIT BOOST CUT AGAIN LAST NIGHT.. as far as i remember I've turned down my boost pressure from 14psi to approximately 10-12psi. But last night as i was having my 'spirited driving' just changed gear from 2nd (4700rpm) to 3rd.. throttle was at 60% then suddenly.. F!#ing S@#t! and alot more of swearing.. it definitely didn't feel good..
I HIT BOOST CUT AGAIN LAST NIGHT.. as far as i remember I've turned down my boost pressure from 14psi to approximately 10-12psi. But last night as i was having my 'spirited driving' just changed gear from 2nd (4700rpm) to 3rd.. throttle was at 60% then suddenly.. F!#ing S@#t! and alot more of swearing.. it definitely didn't feel good..
im lucky enough that the only time i got boost cut was when i had my mbc set to run at around 14psi, and i planted it in the early morning lol... turned it straight back down to around 12.
I think i have hit it 5 times in the 12,000kms i have done in my car. When i had a gauge fitted, it would spike to 15-16 psi in 2nd-3rd change but settles down to 10-11 when in gear. I would say get a better boost controller, get rid of the MBC or just put up with it happening every now and then.
G
Guest
Unregistered
or get the car tuned to suit your mods. a piggy back will do...
a wideband EGO and a FCD (fuel cut defencer/defender),
problem solved,
a wideband EGO and a FCD (fuel cut defencer/defender),
problem solved,
G
Guest
Unregistered
I will tell you all about fuel cut hopefully for everyones benefit.
I will try and step through this slow so everybody can understand what is going on.
WHAT IS FUEL CUT?
Fuel cut is actually a removal of the the injector firing signal from the ECU. This is to say that your engine computer doesn't put fuel in the engine, hence the name.
WHAT CAUSES FUEL CUT?
Despite the rumors of fuel cut being caused by too low of fuel pressure, too small of injectors, high flowing exhaust, high flowing intake, or large turbos fuel cut is not directly caused by any of these. Fuel cut is actually caused by the ECU seeing more air entering the engine than it was originally programmed to use. This likely cooresponds with an injector duty cycle which is unsafe or unattainable. So basically fuel cut is caused by the MAF seeing too much air. Don't ask what too much air is....
WHY DO WE GET FUEL CUT?
Since fuel cut is caused by the ECU seeing too much air we get fuel cut by increasing the air flow through the MAF.
WHAT CAUSES TOO MUCH AIR TO BE SEEN BY THE MAF?
Many things can cause this. basically anything you do to the engine to make more power increases the airflow...way to many to list here.
SHOULD I GET RID OF FUEL CUT?
NO NO NO NO NO...Do not use any device to eliminate fuel cut. Fuel cut is there for a reason. If you are hitting fuel cut the ECU believes that you are moving more air than the fuel system can safely deliver. If you are having to eliminate fuel cut with some sort of defender either you have an inadequate fuel system, inadequate tuning tools, or a leak somewhere.
WHY DO LEAKS CAUSE FUEL CUT?
Since fuel cut is caused by air flow and not actual AFR lost air can cause fuel cut.
SO HOW DO I PREVENT FUEL CUT?
This really isn't that hard. You have to SAFELY reduce the air the ECU sees. This means to deliver more fuel to the engine (assuming you are shooting for the right AFR) per air count. To do this you must increase the injector size (fuel flow per air count) and then use an new ECU program or AFC to decrease the air count accordingly. Not going to get into tuning now.
WHAT SHOULD I NOT DO TO PREVENT FUEL CUT?
Do not decrease air counts without adding more fuel per air count. This will cause you to just run lean all the time and cause exactly what fuel cut tries to prevent. So....
DO NOT JUST PUT IN A FUEL CUT DEFENDER.
DO NOT JUST LEAN OUT YOUR AFC TO UNSAFE AFRs.
DO NOT TRY AND PUT IN LARGER INJECTORS WITHOUT FUEL MANAGEMENT.
DO NOT TRY TO UP THE FUEL PRESSURE WITHOUT FUEL MANAGEMENT.
I will try and step through this slow so everybody can understand what is going on.
WHAT IS FUEL CUT?
Fuel cut is actually a removal of the the injector firing signal from the ECU. This is to say that your engine computer doesn't put fuel in the engine, hence the name.
WHAT CAUSES FUEL CUT?
Despite the rumors of fuel cut being caused by too low of fuel pressure, too small of injectors, high flowing exhaust, high flowing intake, or large turbos fuel cut is not directly caused by any of these. Fuel cut is actually caused by the ECU seeing more air entering the engine than it was originally programmed to use. This likely cooresponds with an injector duty cycle which is unsafe or unattainable. So basically fuel cut is caused by the MAF seeing too much air. Don't ask what too much air is....
WHY DO WE GET FUEL CUT?
Since fuel cut is caused by the ECU seeing too much air we get fuel cut by increasing the air flow through the MAF.
WHAT CAUSES TOO MUCH AIR TO BE SEEN BY THE MAF?
Many things can cause this. basically anything you do to the engine to make more power increases the airflow...way to many to list here.
SHOULD I GET RID OF FUEL CUT?
NO NO NO NO NO...Do not use any device to eliminate fuel cut. Fuel cut is there for a reason. If you are hitting fuel cut the ECU believes that you are moving more air than the fuel system can safely deliver. If you are having to eliminate fuel cut with some sort of defender either you have an inadequate fuel system, inadequate tuning tools, or a leak somewhere.
WHY DO LEAKS CAUSE FUEL CUT?
Since fuel cut is caused by air flow and not actual AFR lost air can cause fuel cut.
SO HOW DO I PREVENT FUEL CUT?
This really isn't that hard. You have to SAFELY reduce the air the ECU sees. This means to deliver more fuel to the engine (assuming you are shooting for the right AFR) per air count. To do this you must increase the injector size (fuel flow per air count) and then use an new ECU program or AFC to decrease the air count accordingly. Not going to get into tuning now.
WHAT SHOULD I NOT DO TO PREVENT FUEL CUT?
Do not decrease air counts without adding more fuel per air count. This will cause you to just run lean all the time and cause exactly what fuel cut tries to prevent. So....
DO NOT JUST PUT IN A FUEL CUT DEFENDER.
DO NOT JUST LEAN OUT YOUR AFC TO UNSAFE AFRs.
DO NOT TRY AND PUT IN LARGER INJECTORS WITHOUT FUEL MANAGEMENT.
DO NOT TRY TO UP THE FUEL PRESSURE WITHOUT FUEL MANAGEMENT.
SiliconAngel
1 AYC Bar
Good explanation there Carsten.
So I think a good point to make is, there is no such thing as 'free' or cheap power. Don't expect to pop a $40 boost controller in, dial it up to 15psi and away you go. 10 to 12 may well be fine, but eventually you'll need to upgrade other components in line with your boost increases.
So I think a good point to make is, there is no such thing as 'free' or cheap power. Don't expect to pop a $40 boost controller in, dial it up to 15psi and away you go. 10 to 12 may well be fine, but eventually you'll need to upgrade other components in line with your boost increases.
G
Guest
Unregistered
there is nothing wrong with FCD's, just as long as your tuner has half a brain cell, he will know not to run the injectors at full duty with the fuel pump screaming its ass off trying to supply 3 billion psi.
all a SAFC does is change the airflow registered at the ECU, to allow you to set your desired AFR on the actual amount of air going in, however you cant play with the timing advance, which in my opinion can be more dangerous than a FCD.
all a SAFC does is change the airflow registered at the ECU, to allow you to set your desired AFR on the actual amount of air going in, however you cant play with the timing advance, which in my opinion can be more dangerous than a FCD.
lol i hate that feel... remember when mine popped right off and i had no idea lmao
G
Guest
Unregistered
never said that they were bad,
only for those who put them in and wind up there boost thinking it will be fine....
as long as you have appropriate tuning..
at the very least run a wideband ego so you know whats going on.
