I just installed my hallman mbc (in-cockpit version) and she runs great, but when I push the fine line between spiking at 20 and spiking at 20.5 I ...think I get fuel cut. I've never had this happen to me in any other car though, so I dont even know if that is what it is. The feeling was like I hit an invisible brick wall, like everything just stopped for just an instant and then kept going again, like the car instantly was off then on again. If that is what it is... since I will only be able to use 93 here, can I get new plugs/ gap them differently in order to run higher boost? One more question bout fuel cut. Is it triggered solely by the amt of boost or is it from the knock reading? if it is from the knock, I dont wanna mess around with trying to raise boost unless I can figure a way to cool my spark, or something to dampen knock. When my friend in his sti comes down I wanna run 22psi, so how can I do this? If its knock causing fuel cut, I can just add some tolulene then right?

 

That is fuel cut. I would get a fuel pump then some type of fuel management (flash) then you will be good to go. Not sure about the knock question sorry.

 

Fuel cut happens when the ECU sees x amount of airflow. To eliminate fuel cut, you need to alter the airflow signal that the ECU sees to trick it into thinking there is less air than there really is (AFC, flash, ETC). Changing a fuel pump or injectors does nothing to combat fuel cut.

 

No I was saying to get a fuel pump since he is running more boost and then get the flash to get rid of fuel cut. The pump is for safety only.

 

Fuel cut at 20.5psi? I've personally ran 23psi with a mbc with no fuel cut..

 

that is not necessarily something to be proud of.... even if you're not getting fuel cut... on pump gas you'd be pulling a lot of timing making much less power.

by what you are describing are you sure you're not in that area where the rev limiter comes in... cuz right before it bounces there is this kind of lull where no power is being made...

 

yea, Ive never even taken my car to the limit... I think I may possibly have hit 7k once... maybe... but not this time.

 

so how did he get 23 psi since all of our cars are programmed the same, shouldnt it read the same airflow on his as it does mine therefore cutting him off at the same? you sure knock/gas quality has nothing to do with it?

 

what rpm do you shift at. that will cause fuel cut.

 

It happens at 1700 Hz Karman value at 20°C and 1000 mbar athmospheric pressure approx. That is roughly 1.2 bars relative boost. Fuel cut is a saftey feature that protects your engine and turbo. Ensure you have the proper supporting mods before removing or fooling fuel cut. DO NOT install an aftermarket "Fuel Cut Defender" as they are scary.

 

advice noted. So number one: it is totally due to boost pressure/air intake?
(meaning I can't just up the octane?)
and number two: I will need some sort of flash/ piggy to fix?

 

It is the combination of boost pressure (relative to atmospheric), outside air temperature and the amount of air you are sucking. When all three values exceed their setpoints, you get fuel cut. That is why we have and will see more reports of fuel cut as the temperatures lowers in the north with the onset of winter.

The recommended path is to add proper supporting mods (as other stated above) then an ECU reflash, piggy back or aftermarket ECU.

Speedlimit..

 

Boost pressure and intake air mass are not equivalent. If fuel cut is truly triggered by reaching a specific level of air mass, a better flowing setup (i.e. more power potential) will experience fuel cut at a lower boost pressure. Boost pressure is simply a measure of how much air is backlogged in the intake tract.

A decent means of recalibration/retuning will alleviate this problem and will allow one to make more power from even a bone stock car.

 

I am experiencing exactly the same thing as described by honki24. Just installed the Blitz SBC id-III EBC and experienced "invisible brick wall" just like the speed cut. the At first i thot it was the boost cut, but after what you guys have been saying... I think its the fuel cut too.

 

yes but boost pressure is proportionally connected to air flow, since it is understood that pressure is not being built without also being consumed (since the turbo never makes boost without the tb being open. I didn't mean that they were the exact same thing, but I was questioning whether it (fuel cut) is affected directly/solely by airflow (and/or) boost.