? about the nature of Fuel Cut.

[SnowBird]

Im a newb to fuel cut. I never had it before. This is my question.

Pertaining to a boost leak, is air leaking out of the system and then in return pulling more air through the filter and the MAS -or- is air leaking into the the system by means of being pulled in from the atmosphere? I tried to explain it the best I could, I thought air was leaking out and pulling more through the MAS and thats why it cuts, but then I started thinking about it too much so thats where this question came from. Thanks, flames welcome.

 

[Bud92gsx]

fuel cut, is actually determined by the ECU...

 

[360glitch]

I have no experience with fuel cut but when you have a boost leak (or a vented blow off valve) you are allowing air to be released to atmosphere that has already been measured by the MAF. The ECU is expecting you to get every bit of air the MAF measured and is spraying fuel accordingly. Of course, this would cause you to have too much fuel being sprayed, not for it to cut? Right..?

 

[JFatch1890]

You running a stock fuel pump??And what turbo you running?And did you try to up your boost with a boost controler haha need to know info to point out problem,Your ecu is cutting off cause your not getting enough fuel..

 

[Bud92gsx]

You running a stock fuel pump??And what turbo you running?And did you try to up your boost with a boost controler haha need to know info to point out problem,Your ecu is cutting off cause your not getting enough fuel..

But if you upgrade your pump to a 255, you need a FPR.. A 190 pump I don't think you need a FPR. Get some kind of boost controller, and set at 14 PSI, so you don't get fuel cut...



Bolt-on Modifications
Ported 14B, O2 Dump, 2G manifold, 2.5" downpipe to 3" with cut-out and Megan racing muffler, ported from exhaust manifold back to O2 manifold, Gutted as far as I can take it without taking out windows. Emissions removed. Running Mobil 1 10W30.
Engine Management
MBC with Gauge. Not seein over 15psi yet.


He shouldn't see fuel cut at all!!

 

[steve]

Your ecu is cutting off cause your not getting enough fuel..

No the ECU cuts off the fuel because it's seeing more air flow that it ever should and thinks the wastegate has malfunctioned.

A boost leak will cause the turbo to draw in more air and work harder trying to keep the pressure up. That air has to come by the MAF and is measured. Once the airflow per rev reaches the limit programmed in the ECU it starts cutting fuel and if your not wearing your belt you get close and personal with the dashboard and steering wheel.

A boost leak test is the first step when you get fuel cut.

 

[Bud92gsx]

Steve...A boost leak will determin when and if you get cut, before the ECU says it's time??

 

[steve]

Steve...A boost leak will determin when and if you get cut, before the ECU says it's time??

What?

A boost leak test will help you identify where the leaks are and help you fix them all.
People can still get fuel cut without any leaks until you modify the ECU software to remove the checks but you have to be pushing quite a bit of air to cause it normally.

 

[Bud92gsx]

I know this is what you do all day long five days a week, which is awsome cause your freakin smart... You know that's really all I have to say about that..I'm going to let Steve school all of us on this Issue...

 

[SnowBird]

Bolt-on Modifications
Ported 14B, O2 Dump, 2G manifold, 2.5" downpipe to 3" with cut-out and Megan racing muffler, ported from exhaust manifold back to O2 manifold, Gutted as far as I can take it without taking out windows. Emissions removed. Running Mobil 1 10W30.
Engine Management
MBC with Gauge. Not seein over 15psi yet.


He shouldn't see fuel cut at all!!

I dont think you understand fuel cut that well. The MAS or ECU sees too much air coming in and cuts fuel. It has nothing to do with me needing more fuel, it has to do with my boost leaks.

 

[JFatch1890]

haha my bad!!Never had a boost leak cause fuel cut on me before,Its basically saying the ecu is programmed to receive a certain ratio of fuel and certain ratio of air,And if it receives to much air the ecu cuts the fuel?? Or am i way off??haha id like to know for future reference cause i aint trying to eat my steering wheel haha

 

[Bud92gsx]

I dont think you understand fuel cut that well. The MAS or ECU sees too much air coming in and cuts fuel. It has nothing to do with me needing more fuel, it has to do with my boost leaks.

You are correct I don't understand allot of things, like I have a PHD. But you are correct agin, the ECU is seeing unmetered air and is cutting, or trying to compensate.. IC Pipe Tester

 

[steve]

But you are correct agin, the ECU is seeing unmetered air and is cutting, or trying to compensate.

No it's seeing metered air and saying "Dude, somethings really wrong here, this shouldn't be happening".

 

[SnowBird]

You are correct I don't understand allot of things, like I have a PHD. But you are correct agin, the ECU is seeing unmetered air and is cutting, or trying to compensate.. IC Pipe Tester

The ECU doesnt see unmetered air. Unmetered air is air the ECU doesnt see, like if you would run the recirculation tube off of your BOV and it would suck in from the atmosphere. Hence the name unmetered. The ony way the ECU sees air is through the MAS, so if it doesnt draw in through the air filter the MAS doesnt know its there and is termed as unmetered.

You are kind of on the right track, kinda. Instead the ECU sees TOO MUCH air cuts the fuel before you can run super lean. It cant compensate, thats what a standalone or an expensive fuel controller does I think.

 

[JFatch1890]

Yeh that's what i meant,Just didn't know how to word it,My bad but thanks for the info guys