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

 

[carsaval]

hi guys i need help/advice
I have a be316g 560cc, safc2 and I am getting fuel cur after about 4k rpm and it gets worse in higer gears. I am going to run a boost leak test soon and fix that, because I know I have one because my car will sometimes throw a check engine light becasue of idle speed because it is about 1k. Is this all boost leak related or do i need to get a biggger fuel pump.

 

[jking29]

Fuel cut is not actually running out of fuel, that would just cause it to go lean. Fuel cut is caused by overrun of the mas. How much boost are you running? Do you have a logger? What does your mas read when it does it? What are your idc's? I would do a boost leak test as I would pretty much guarantee you have a big one.

 

[zilo900]

boost leaks are always bad, so fix that first, then see what problems you have left

 

[appleyard777]

Fuel cut is not actually running out of fuel, that would just cause it to go lean. Fuel cut is caused by overrun of the mas. How much boost are you running? Do you have a logger? What does your mas read when it does it? What are your idc's? I would do a boost leak test as I would pretty much guarantee you have a big one.

not typically man, its usually a case of running overly rich! i too was hitting fuel cut with my e316g setup, found out i had a pretty bad boost leak and my car was trying overcompensate for it, causing you to run rich as shit, i was shooting out black smoke like a mofo , and i had also tryed to overcompensate for it with my safc by leaning it out, anyway fixed the leak, got my safc set adding a little more fuel because i had it leaned out from the boost leak, anyway no more fuel cut, no more smoke, just pulling like a raped ape till redline

 

[carsaval]

ok thanks for your responses guys. Oh and as for how much boost I'm running Its around 14 psi, because I have my boost controller disconnected. I had too because I just went with a 3 inch downpipe and it made a difference.But I am guessing that just made things worse . I will boost leak check it as soon as I can and post what I find out I am going to PULL-A-Part today. and going to look for a 1g throttle body, and a 6 bolt block, because I'm popping out of first sometimes, so I am pretty sure my block is about to walk out the door. Any input on this would be awesome.

 

[JayRolla]

because I'm popping out of first sometimes, so I am pretty sure my block is about to walk out the door. Any input on this would be awesome.

Ok popping out of first would be a tranny issue. Also even if you blow your motor your block will still be good.

 

[carsaval]

ok so the popping out is a tranny problem. I dont think I blew my block, its a 7-bolt and as everyone should know mitsu engeeners slept on the job during the production. go It doesnt happen when im driving though just when I first put into gear.

 

[DSM-Talon-John]

WEll what does it feel like when your hitting it. That might not be what it is. the extra flow clould be causing you to boost higher but i doubt thats it.

 

[TurkF26]

Yes if you have a big enough boost leak, and it feels like you just hit a brick wall, a big enough boost leak can cause that. When i had my 1g AWD talon, I had just replaced the LICP and it somehow came a little loose. Anytime i would go over 8 lbs of boost, the car would all of a sudden jerk me forward and feel like i slammed into a brick wall. If you have a totally stock setup (minus the exhaust) then 99% chance you have a boost leak.

 

[Batman™]

yeah that's fuel cut.

 

[DSM-Talon-John]

Ya thats fuel cut, just do a boost leak test. Dont you have a boost gauge.

 

[95blackGsTurbo]

You get fuel cut from boost leaks. So if you hit fuel cut, it's because you have a boost leak and the car is having to pull in over 2400Hz to maintain boost.

 

[nyk4life]

i was at wot today in second gear and it held at 14 psi until about 5500 rpms and when i switched to third, i spiked to about 18 psi held for a couple of seconds and i hit fuel cut for the first time in my car. ive got no boost controller? im not really sure what caused this, boost creep?

 

[DSM-Talon-John]

IM thinking exhaust is the main factor there, are even sure its fuel cut? Did it feel like it just turned off and then turned back on(power wise)

 

[oldman]

Boost Leak Test.

 

[nyk4life]

well it felt like i hit a wall i suppose, like a quick jolt, i am going to go make a boost leak tester today to see ### happens, if i do find a leak, it can cause fuel cut?

 

[oldman]

Boost leak is the number one cause for hitting fuel cut.

 

[nyk4life]

thank you, ill do the test a.s.a.p.

 

[oldman]

You're welcome. While I'm flattered that you're taking my word for it, I think you should search the topic "fuel cut" and try to understand what causes fuel cut, this is probably one of the most discussed items on the plate due to the fact that the name implies running out of fuel when it actually has very little to do with fuel. If you have more questions after search you can post it up here along with your boost leak test results.

 

[MrBoxx]

search the topic "fuel cut" and try to understand what causes fuel cut,

This FAQ by crankbender is where I would start. It's pretty informative and gives a great overall view of fuel cut, along with what to do and not to do to prevent fuel cut.

 

[nyk4life]

i knew a little bit about it before, i understand fully ### can cause fuel cut and how it happens.

 

[mhuffman]

I was getting a fuel cut around 5k rpm's, but it was not a boost leak. If anything, a boost leak means you need less fuel because less air is getting into the engine.

I replaced my old fuel filter (a big restriction) and the fuel cut went away immediately.

 

[gob4sho89]

once in a while i feel the same thing at 3k rpm but only sometimes, like pulling out of my sub early in the morning when it is around freezing outside. it only happens when accelrating 60-100%. i never feel it in 1st, bearly in 2nd, but 3k in third and slam into the invisable wall i go, before i can react its over. Never hapens in 4th or 5th. I cannot figure it out...

 

[DSMunknown]

Just for reference:




http://www.dsmtuners.com/forums/showpost.php?p=151091608&postcount=7

 

[mhuffman]

Just for reference:

http://www.dsmtuners.com/forums/showpost.php?p=151091608&postcount=7

I have already read this statement from the FAQ. Is it from the eclipse FSM? Given that it is a true statement, it still doesn't contradict my statement about fuel delivery.

I think that under certain conditions such as fuel starvation or inadequate fuel pressure, the ECU will cut ignition to prevent a potentially disasterous lean condition. I bought my DSM used and i bet the fuel filter was old and clogged, so once i did my first exhaust mod the fuel demand was greater, and the filter couldn't keep up with the flow. I got 'fuel cut'. The ECU detects low fuel pressure or a lean condition and cuts igniton to prevent dangerous engine conditions. So, it seems that the ECU might trigger 'fuel cut' in the case of inadequte fuel delivery.

-I do my first exhaust mod, make more power, and get fuel cut.
-I replace fuel filter and change nothing else.
-Fuel cut goes away.

This doesn't seem like coincidence, and supports my theory on 'fuel cut'.