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

 

[h3o]

haha sorry i was only assuming cause im in hawaii and the coldest we get here is like upper 50's and thats only at night and during the winter.

 

[95blackGsTurbo]

What kind of MBC do you have. At 11 psi you should not be having fuet-cut. I don't have it on stock injectors with a 16g at 15psi. You said you screwed your boost controller screwed all the way in? On my Joe P. all the way in is maximum boost. Might want to try screwing it out a little bit. Do you have an aftermarket boost gauge or not? Also what plugs are you running?

 

[Corpssnare]

That definitely sounds like fuel cut. I hit it once in my old car when I was beating the crap out of it (Saturn SC2) revving up to 7.5k (redlines at 6.5) and it felt like I hit a brick wall. I'm not sure how you'd get fuel cut at 10-11psi since that's stock boost anyway. How high were your rpm's when this happened?

 

[HyperGSX]

i have new plugs on there. The mbc is tightened all the way down, so the car is running stock boost. This usually happens around 4-5k rpms. I have a boost gauge also and it hits cut after 12 psi

 

[out there]

properly gapped plugs? wires? have you checked to make sure the mas is clean? i'm not sure how likely a dirty mas is, i've never run into it, but i would look into everything that might have an impact on how much fuel the ecu sends.
profile says you're running an afc, have you experimented with the settings? might want to get a logger and see what the ecu is reading out when this happens

 

[3134]

I have a 97 eclipse gst with a small 16g turbo, catback, 190 fuel pump and that is about it for performance mods. My dad recently called me to tell me that When he accelerates at higher rpm the car dies and feels as if you "are taking it out of cruise control" and slightly are applying the break. He told me the car stays on but you can not push it or this always happen. It is more prone to happen when you are going up hill and it will happen at lower rpm. I have not touched the boost level on the turbo so it should be at whatever it comes at from slowboy racing. I wonder if the boost is spiking and then the car is fuel cutting due to the increase in boost? anyone know what the problem may be? please help

 

[blackGSX2g]

I believe stock wastegate pressure on those turbos is around 9lbs, so I highly doubt you are pushing too much boost through it ( though you really should have an aftermarket boost guage).

My guess is that you are just getting too much fuel from your 190 pump and its just bogging down. I know when I first put my pump in, I had to dial back a fair amount of fuel especially at WOT.

 

[3134]

I have an safc 1 that i plan on installing along with an autometer boost gauge and autometer air/fuel gauge. If i tune these appropiately will my problem most likely be solved? I have had this turbo and 190 fuel pump (installed at the same time) in the car for about 3-4 months without a problem until right now.

 

[ddavisaf]

It would be a good idea to pull your spark plugs and check to see how bad they are. It's sounding like they're fouled.
Remember to swap in NGK BPR6ES gapped at .028"
Yes, your problem will be fixed with the SAFC install.

 

[90CherryTSI]

Have any pipes popped off and not retightened properly? Sounds like a big leak, same thing my car did with a leak. They'll come up in the worst spots. Test, tighten, listen, test, tighten, listen

 

[3134]

wow, holy shit i totally forgot... Its the upper intercooler pipe! this happened to me awhile ago when the upper intercooler pipe came out. it is probably just the amount of air going into the car

 

[jaredgsx]

sounds like a boost leak, 99% of fuel cut is because there is a leak somewhere so a safc will not correct it totally. There are a lot of things that have to be taken into account. i would do a boost leak test. go to the vfaq and it will show you how to make a boost leak tester. From there check to see what your plugs and wires look like

 

[Evil1gDsm]

sounds like a boost leak, 99% of fuel cut is because there is a leak somewhere so a safc will not correct it totally. There are a lot of things that have to be taken into account. i would do a boost leak test. go to the vfaq and it will show you how to make a boost leak tester. From there check to see what your plugs and wires look like

There are many causes of FUEL-CUT; boost leaks, Running to rich / lean, Over-running your stock maf, over-running your injectors!! Many conditions have to be taking into account like ya said!! I'd say...Boost leak test your car, find someone who has a "Pocket-Logger" and log your car!!!

 

[jaredgsx]

yes logger is a must

 

[3134]

i purchased a logger and and an safc, i just havent had time to put it in since i am not around

 

[Evil1gDsm]

i purchased a logger and and an safc, i just havent had time to put it in since i am not around

When u get your logger, it will make tuning / Diag of your problem soo much easier! Good luck man!!

 

[3134]

thanks, i should kno if it is def the intercooler pipe that is slowing the car up 2morrow. My dad will check it

 

[HyperGSX]

plugs are propely gapped, i think i might have a boost leak at the top of my bov could that be a cause? BTW, i need to update that i have no longer have an safc. MAS is clean as a whistle

 

[out there]

leaky bov doesn't sound like a possible culprit. have you checked to make sure your fuel system is in proper working order (pump, filter, injectors, etc)? i'm really running our of options for what i have experience with as being the cause of something like this.
i don't know of any 2g specific mas problems (ie 1g still having both honeycombs), so i won't go there.
when does this happen? about the same rpm every time? any specific gear? all gears?

 

[3134]

Ok so i checked the intercooler piping and it is all connected so i know it is not that. So far i was told that the problem may be a boost leak, plugs(wires i guess also), or fuel cut. Just to kind of explain the problem again, it happens at higher rpm and it feels as if something is tugging at the car and slowing it down when i try to accelerate. I was under the influence that a fuel cut is when the car shuts down, which mine does not do. I also didnt think plugs and wires could make such a dramatic change in acceleration though my plugs and wires do need to be replaced. I do plan on changing them, but i really want to see if someone had this same problem or knows what it most likely may be because then i can fix that first.

 

[90CherryTSI]

What's your vac at? Plug the boost gauge into the vac line and check it. You don't have to fully install it but check your vacuum. I'm betting you have a leak somewhere. Build a tester and test it. My friend's 91 had an extra vacuum T in the fpr to gauge line and his vac was 5. At higher RPM's he had no pull at all. Put a nipple on the T and back to being good. First indication was crappy vacuum. Plug up the gauge and check it out.

 

[3134]

so how do u correct a boost leak? or better yet, what is the cause of one? I do have a used 1g bov, could that be maybe what is causing it?

 

[Travi2506]

What's your vac at? Plug the boost gauge into the vac line and check it. You don't have to fully install it but check your vacuum. I'm betting you have a leak somewhere. Build a tester and test it. My friend's 91 had an extra vacuum T in the fpr to gauge line and his vac was 5. At higher RPM's he had no pull at all. Put a nipple on the T and back to being good. First indication was crappy vacuum. Plug up the gauge and check it out.

Alrite, i'm not having any accel. problems, but i'm hitting fuel cut and my vacuum is around 20 at idle, so i don't think there's a leak, i'll probably test it when i get a minute, but is there anything else that could be causing the fuel cut?

 

[90CherryTSI]

That all depends on where it's leaking from. If the BOV then maybe it's the gasket, get a new one. If it's a hose clamp, tighten it down a little more. It could be leaking from pretty much any connection. The cause of them? Improperly tightened hoses, 15 year old parts breaking, brittle gaskets finally giving way. No clue if your 1g bov will fix it or not until you know where the leak is coming from. Here's what you really need to do -

Build a boost leak tester and get an air tank and test.


You'll spend alot more money throwing parts at it and it could be as simple as a bad vac line.

 

[90CherryTSI]

a brick wall.

Pretend you're WOT, flying up on someone, and then...BAM, literally, there's nothing, no acceleration at all, like the car just died. You get whiplash, you think you're dead, let off the gas, gently back on, you're ok now. That's fuel cut.

Listen to us

A BOOST LEAK WILL CAUSE THIS SO TEST YOUR CAR BEFORE YOU DO ANYTHING ELSE!


EDIT - You said above -

it feels as if something is tugging at the car and slowing it down when i try to accelerate

and then you said -

i'm not having any accel. problems



Are you slowing down while trying to accelerate, or are you not?