Fuel Cut: What is it? How do I fix it? [merged]

[Slanted J]

All fuel cut threads are combined here.

I've tried doing a search but to no avail.

I was just wondering what Fuel Cut is. I've heard it tossed around alot, but do not actually know the details behind it. And, naturally, I can gather that its when the fuel is cut off, but when and why.


Thanx,
Jon

 

[iowaboostin]

Are you 100% it's fuel cut in the first place? Experiencing fuel cut is like hitting a brick wall... if it's just stuttering, check your plugs/wires. With the 255lph you're going to want an AFPR, then of course some management (S-AFC), re-wire it while you're at it too.

 

[Defiant]

Fuel cut is a matter of air volume intake, not fuel supply. You could put a turbine pump off a Saturn 5 on there, and the ECU is still going to choke you when it sees more air coming in than it wants the engine to get.

 

[o0_pyro_0o]

I just got my new Big 16G installed and I'm now experiencing fuel cut even with my boost turned low (I'm assuming it's due to the COLD air at night) and so I'm shopping for the solution. Right now I'm planning on getting the Apex'i Super AFC, injectors, high flow fuel pump, and fuel pressure regulator. Is that everything I need to eliminate fuel cut? Also, what size injectors should I get? I was thinking 550's but from the shearching I've done it looks like I may want to go bigger.

 

[DaOnE51T]

At what boost does fuel cut usually occur at? I was wondering if my car was hitting fuel cut. Right now my car is creeping to 20 psi and it doesn't stutter under WOT. THANKS, PEACE 1

 

[Generation1JeY]

as another member put it rather humorously, "you will be picking your teeth out of the steering wheel."

If ur hitting fuel cut, u'll now it, the engine just completely shuts off for a second and u dont accelerate at all. On my car it happens only at WOT sometimes when its cold out and my engine is cold, but if u hit it u will know it cause it will jerk u forward, it feels kinda like giving it full gas in first gear and then at 4k rpm just dropping the gas and not putting the clutch in, .

 

[David15151]

yep totally sucks.. happened to me when i was WOT .. its just started raining hard out of no where.. bam fuel cut as it sucked in that cold air.. its like hitting a brick wall .

 

[DaOnE51T]

whats your knock count?

I wouldn't know because I don't have any tool to determine it. All I know it doesn't ping if that matters. I guess I didn't hit fuel cut yet. THANKS, PEACE 1

 

[steve]

Still pops and studders at 4rpm on... dont get it?

Pops and stutters isn't fuel cut. Fuel cut is pretty violent switching from full power to no power to full power as the engine crosses the airflow trigger threshold.

Steve

 

[tom1995tsi]

I was pulling onto the highway last night and I floored it, the car felt fast as hell because of how cold it was, All of a sudden the car jolted a little bit and made a weird choking noise. Its happened before but it happened 2 times last night and for some reason I was creeping i guess because of how cold it was i dunno though. What do you guys think it could be?

 

[oddrob]

How much boost were you running? Fuel cut usually feels more like hitting a wall than a little jolt.

 

[tom1995tsi]

I wasnt paying attention to what it was at, but it was creeping really bad last night. Prolly 15-18.

 

[HotSauce GS N/T]

ok to set the stage ill give the background specs on my car

1g tsi awd, dejon tool intake and all the free mods, -30-0-30 autometer boost gauge

i just got done installing the johnnyracecar fmic, my welder buddy and i made custom hard ic piping from turbo outlet to tb and welding on a bov flange

ok no for the problem:

everything was running great untill tonight, here in upstate ny we are running about 25 degree weather at night so im thinking its a fuel cut problem
i would accelerate at wot and at 11 psi the car would suddenly jerk hard but keep accelerating till it would do it again about the same time.

is this fuel cut or something else i have to worry about

thanks alot
-kyle

 

[Parsalian05]

just thought id add that im having the exact same problem. im done with all stage 1 mods (evo16g) and now i cant boost past 10psi without it jerking . before i did exhaust (which i did last) i was able to boost 17-18 with no probs... so i dunno what happend.

-nate

 

[BoostJunky4G63]

Does it pop and blow a cloud of smoke out when it does it?? It most likely sounds like fuel cut. I have the problem of boost creep and hitting my fuel cut right now...damn stock fuel

 

[HotSauce GS N/T]

it kinda jerks hard and stop accelerating till i let off the gas or shift i havent noticed any smoke since i figured it was bad for the car/engine and only did it 3 times by accident :thumbdown im hoping its only fuel cut and not something more serious

 

[99gst_racer]

Yeah, sounds like fuel cut. Fuel cut feels like hitting a pot hole at WOT.

 

[saw22]

Sounds like fuel cut, but you may be explaining it mildly. Im having a boost creep issue right now and have hit fuel cut the past couple times I drove the car. If it happens again, see if a big cloud of (brownish) smoke blows out of your exhaust. I have seen that everytime. Im sure people behind me love it.. :thumbdown

Good luck!

 

[TurboSam]

It doesnt seem like my car has any problems until it reaches boost. When my boost gauge reads 0 psi I hit like a fuel cut(it bogs out and feels jerky like many boost cuts)? My a/f gauge reads lean most of the time and sometimes it completely reads nothing. I rewired my walbro 255, all my hoses to and from the fuel regulator are good. I'm thinking its the fuel pressure solonoid or the bcs, not reading right. I don't understand how the whole system works so I can't figure it out myself. Some one please help, i've been fighting this for a while now. Thanks

 

[dalepmay]

Sounds to me like you need to tune your SAFC, make it richer. If you do not have a SAFC, you really need to get one, especially since you have modified your fuel system.

 

[Lazer RS]

Alright free mods done, 2.5 all the way to the flex, no cat, stock 14b, mbc
normally i would get fuel cut at 17 psi, now ever since i got harmonic dampener pulley done things have been messed up. i never adjusted my mbc; it was at 15 psi, but now i only boost to 13. and get fuell cut at 13 psi @ 5500 rpm. what is up! the dampener wouldnt have made any difference. help

 

[TurboSam]

I thought that but this problem just showed up one day. I first put in my 3 inch exhaust, then bolt up a big 16g, then pit in my act 2600 and flywheel and then 50 miles later bam this starts happening. My safc should come in tomorrow, Im going to hook that up. I'm brand spanking new to safc and have no clue where to start is it easy to do or what? I aslo do not have a datlogger is that a must or can I tune with out it and get one later? Do I have to get bigger injectors? what injectors should i get?

 

[Endz0r]

sounds like a boost leak if you ask me. i had fuel cut a few days ago (messed with the MAFT wrongly), and it wouldn't hit fuel cut until i had at least 10psi.

 

[DSM90AWD]

Fuel Cut is a function of total airflow read by the ECU.. of which boost is but one of three factors. Barometric Pressure and Air Temp are the other two.

Also check for boost leaks as the your MAS may be reading more air than is actually getting to your Engine.

 

[HotSauce GS N/T]

what could be the cause of this fuel cut, im only running stock boost and im almost positive all the new ic lines are air tight because we welded them perfectly. Is there anything else to look for when determining how to fix this?

 

[99evo3gsx]

The colder air at 25 degrees may play a part in it. The colder air will be more dense, so you will have more air mass entering the engine. Also, what kind of fuel are you using? Low octane fuel and cold weather can contribute to fuel cut. I used to run 89 octane and hit fuel cut all the time...that's why i turned the boost down to 12 psi. I switched to 92 octane and i now run 16+ psi easily.