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

 

[No_Skillz]

You might be spiking because the source of boost is so far away from the control unit. I don't know much about these fancy pantsy controllers, so I can't offer much to help you there.

 

[SpoolinTalon2]

well my friend has a 99 gst with some mods. but he gets crappy ass gas mielage(sp). what can be done to tune the gas mielage(sp) or fix it? he says he finishes around tank a weekend. or is this just normal depending on the mods? thanks.

 

[tallywacker]

You need to be more specific with what you are asking if you want an answer.

 

[SpoolinTalon2]

ok what im asking is, can he be able to get more miles to the gallon by doing some kind of tunning or changing/fixing something? or beacause of the mods he has (i can list them if you want) he will be getting this mileage? maybe this is a little more clear. thanks.

 

[toecutter]

Yea, list his mods. But this doesnt have anything to do with fuel cut does it?

 

[DSMcamaro]

Well gas mileage is not really related to your title "fuel cut" but go ahead and list the mods he has.

 

[SpoolinTalon2]

alright, here they are:
t-28 turbo
intake pipe
fuel pump (dont know if 225 or 190)
intake filter
stock exhaust with no cat
upgraded rods and pistons (dont remember what brand)
upgraded side mount (dont know the exact measurements)
safc II
palm pilot pocket logger
engine rebuild about 21,000 ago

i believe thats it.
but doesnt fuel cut reward you with crappy mileage?

 

[DSMcamaro]

http://www.dsmtuners.com/forums/showthread.php?t=186971

I would do a boost leak test and a tune up. How crappy of a gas milage are we talking here?

 

[SpoolinTalon2]

i will try to do a good average on it this weekend. yeah i suspect a boost leak, but the tune up doesnt seem like it needs to be done yet. thanks for the link. would gettin slightly bigger injectors and tunning it with safc II help? thanks.

 

[TerminalTalon]

Yeah this is about fuel cutoff at 4000rpm. The car will go to a shop wednesday so they might figure it out. It feels like I advanced my timing a shit load at 4 grand. My safc reads like a 2 yo with a crayon. I also know I am running really rich. The exhaust and engine bay smell like fuel. I think I might have a leak by the injectors. It is weird. I have been putting fuel treatment 108 hasnt done anything yet. But it really is a octane booster so hmmmm. Oh well if you can help me out it would be much appreciated

 

[Turbo Talon 111]

man that is the worst description of a problem. it sounds more like a rant than asking for help.

 

[TerminalTalon]

Ok then. I have a t3/t4. I start to make boost around 3 grand. At 4 grand it seems to be "fuel cut". I have read others stories, but want some help myself. I am a "newbie" so I have not yet figured out how everything works. The only thing I hate is that I cant even top my fairly new car out because I can only go 80mph before this happens. Please help Sorry about the other ?. I was trying to be funny.

 

[ez1286]

How much are you boosting? Do you have any fuel upgrades? T3/T4 is pretty nonspecific.

 

[TerminalTalon]

I currently have 660cc injectors, SFP turbo header, tial wastegate, t3/t4 hybrid, thermal exhaust, greddy type s BOV, Dejon intake, custom 2.5-3" intercooler piping, massive fmic "dont know dimensions", Mustang tb, Bj's intake manifold, Ported and polished head with bronze coating and titanium retainers. I think I got it all. I turned the boost down but I have a profec b and it is giving me problems. I think it worked a bit. I think I was running about 18psi with this happening. Turned it down and I think on the profec b you can only go as low as 14psi. The profec seems to switch between low and high boost without me doing anything. The button doesnt work either so if anybody has any suggestions that would be much appreciated. Thanks

 

[stickshift69]

Hi everyone, this is my first post here and still catching on to the whole dsm thing. Today I put on my manual boost controller and never felt anything like the fuel cut that our cars are supposed to have. I searched for a while and could only find that it is supposed to happen at anything over 16psi when the fuel system cannot support anymore. When I was dialing in my boost controller I was very cautious as to how high my car boosted to and a couple of times it went to 20+ psi! But no fuel cut. After that I got it set comfortably to 16psi. My car is stock except for my list of mods in my profile. I am also aware of the dangers and trouble spots associated with these cars as I have done alot of research here before I began modding it. Any experiences would be appreciated.
thanks

 

[keymaster]

Well, since you have a fuel pump rewire, that probably stopped it. Yes, it does exist, I hit it once on my T25 when I spiked it to 22+psi. I'd be very careful about how high you boost on a mostly stock fuel system.

 

[allgripnoslip]

If you are at 20+psi for a millisecond it shouldnt happen. Fuel cut is based purely on airflow that the MAF measures and nothing else. My car has a huge boost leak that I am fixing this weekend that gives me fuel cut at only 15psi. Because there is a leak in the intake system after the turbo, the boost is being leaked out so the turbo has to be boosted more to stay at 15psi when really its flowing alot more air than it would be at 15psi, in which case the turbo is inducting more air causing the MAF to measure more air flow and cause fuel cut. Fuel Cut is a result of the MAF reading a preset level at which the ECU determines is unsafe and cuts fuel and spark. This is why the AFC can raise the limit at which fuel cut occurs. Seems like you know what to do and what not to do on a stock fuel system, just stay where you are at. This is a great guide also.



RRE's Injector Chooser Assistant
T-25 14B 14B@18 psi, Upgrade Turbo 20-21 psi Upgrade Turbo 24-26psi
~16 psi ~16psi Upgrade Turbo 17-18 psi

91 Octane stock FP upgrade 550cc 660cc nope!

93-94 Octane stock FP upgrade FP upgrade 550cc 660's or 550's with addl. Pressure

Race Gas stock FP upgrade FP upgrade FP upgrade 660's or 550's with addl. Pressure





go here about halfway down http://www.roadraceengineering.com/eclfuel.htm

 

[TwoLiterLaser]

... When I was dialing in my boost controller I was very cautious as to how high my car boosted to and a couple of times it went to 20+ psi! But no fuel cut. ...

How were you dialing the boost pressure? I can dial in 16psi and never hit 20 psi. Did you start with the mbc tightened all the way down, then backed it off, or did you start with the mbc off then tightened it down? Guess which one is the right way, .

 

[stickshift69]

Yeh, I got confused with my crappy ebay boost controller! I had it set in the middle for the first run and started screwing it in from there. Turns out that it has to be screwed back for lower boost(like I read here) For $15.00 my boost controller works bretty good, no spike, leaks, or anything like that!

 

[TerminalTalon]

I think the problem is done. I got a little boost happy I guess. I turned it down and it hasnt done it since. I still dont know exactly what psi but it doesnt matter. I am going to get the FFWD high flow kit to get more boost and a wideband so I should get 400+ after some dyno tuning. Wish me good luck

 

[yukondoit]

Ok, at first i thought it was bad gas so i reset my ecu but it feels like my car is fuel cut around 4-5000 rpm, usually when im cruising and then step on it to pass. i've done a boost leak test and found two leaks, one is the idle adjustment screw, the other is base of my 1g bov. I think there is cracks in the casting and i plan j/b welding it later today.

is it possible that i may be spiking so bad that its fuel cuting? my profile is up to date.

Mike

 

[Xplicit93AWD]

To start how much is your boost set at? And also fix any leaks you have and try it if continues let us know with more info so we could help you out.

 

[crzyplace1335]

I had the same problem on with my talon turned out to be a vacuum leak. i would do like xplicit said and fix all your leaks first

 

[reNgrOets19]

My car started doing what sounds like the same thing when i got it out this year it cuts out between 5-6k and then it stopped doing it for like 2 weeks and started doing it again if u fixed yours please let me know what u did thank you.....

 

[Rex2342]

It sounds like your just breaking up and not getting fuel cut. My 90 would fuel cut like a SOB when it was colder outside. Fuel cut is best described as hitting a brick wall! You'll know when it happens! The problem your having could be caused by improper tuning or maybe even MAF over run. Is the MAF hacked at all? Try backing down the boost to 14-15 lbs and see if it still does it.