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

 

[steve]

So wait, how can it be my clutch if it's an automatic?

Time for you to read.
http://auto.howstuffworks.com/automatic-transmission.htm
http://www.familycar.com/Transmission.htm

Steve

 

[abaum565]

Ok, I have never owned a turbo'ed car before but I'm familiar with building and maintaining engines. I bought my 1998 GS-T 2 last summer completely stock and it ran great. I have done all of the maintainance on it and recently installed an intake, and put on the apex'i N1 turboback system.

Now when I accelerate hard the engine seems to cut out and it kind of jerks at higher rpm. I have read about fuel cut and that seems to fit, but it is hard to explain what is happening without driving it. The engine clearing cuts out.

Could this also be a bad T25 ### i know that many people have problems with them over 100,000 miles and i just turned over 111,000. If anyone has had this problem could you please give me your two cents. Thanks guys.

 

[DSM-Talon]

I dont think its either of those. I think you have boost leak, you said you recently installed a Intake did you hook up all the hoses going to the intake. I would suggest a boost leak test. I recently had the same problem(today) and fixed it, it was a boost leak, give it a try.
heres a link on how to make a boost leak tester. http://www.vfaq.com/mods/ICtester.html

 

[JLangevin]

And could very well be old spark plugs, improperly gapped, wires, clogged fuel filter, etc... based on your decription, it could just be an entire host of things...

 

[abaum565]

yeah i forgot about a possible boost leak. Thanks guys

 

[andymoraitis]

Typical procedures for stuttering are:

1. New plugs
2. New Wires
3. Boost leak test
4. Check all vacuum lines
5. Replace fuel filter

Let us know what you find out,

Andy

 

[abaum565]

So i ran a boost leak test and it came up negative. I didn't hear any leaks at all. The only air that came back out was through the BOV. So i tightened all of the clamps and took her for a run first nice and easy then boosted it up a little. It still stuttered a little. So tonight i went to get new fuel filter and plugs and i will change them tomorrow.

So now a couple hours after running the test the check engine light comes on. Anyone know why it would possibly come on now?

Thanks guys.

 

[ndsti]

What's the cel or code? Do you have a boost guage, if so whats the reading? I recently had fuel cut because I hit 16psi and it maxed out the fuel system.

 

[mitsu420at]

change your plugs again . a boost leak will cause your plugs to foul out

 

[Turbo Talon 111]

if you get the CEL checked at autozone or something it will help us diagnose. also let us know what boost you are hitting. if you don't have a real boost gauge get one. the one in the dash is not accurate.
an intake and exhaust could very well be giving you enough air through the motor that you could get fuel cut. also the downpipe could be flowing air past your wastegate that would cause creep and this could easily get you into fuel cut. check on the CEL and your boost level and report back. that will help alot.

if you want to check your turbo is ok, pull of the intake and look inside the turbo. check that the fins are not obviously out of shape and that the blades are not hitting the inside wall of the housing. then grab the shaft and pull it in and out. it should have little to no play. side to side play is expected as long as the blades aren't hitting the housing.

 

[abaum565]

I got new plugs and new wires and that seemed to fix the stuttering. The #3 plug looked like it has seen better days along with the rest of the them. Runs like a champ now. Thanks guys.

 

[ryno]

Im not really a noob to DSM's, but really feel like one with this dumb problem. I think im hitting fuel cut? Ive tried researching and cant find exactly my problem. I was making some pulls on my car tonight. In 1st and 2nd my car will pull hard to redline just fine and feels amazing! But as soon as i get into third the car seems to not pull as hard and also as soon as i get to 5kish RPM's it just pops real loud and goes back down in RPM's. the car will then drive just fine. I cant find any major boost leaks at all. Ive tried logging but just cant figure it out. I have pocketlogger but it wont seem to allow me to read the actaul numbers.(Also where does it plug into the computer? I have the cradel but cant find where to plug it in at) I have seen im pulling around 25+ degrees of timing, but the timing is just fine in neutral, right at 7. Also plugs are pretty new along with all new VC gaskets. I was running 16psi. The car has doner this for the past 6 months. Im just fianlly getting into racing at the track and want to figure this out.

Am i hitting fuel cut? And if so what can i try next.
If not, any suggestions for the problem?

 

[donmagicjuan]

Uh, are you sure you mean the ECU is pulling 25 degrees of timing? At around 5000 RPM, that would mean you are not getting a spark until after TDC! I'm not familiar with the pocketloggers, but it would really help us if you could figure it out and post a log. That way we're not just shooting in the dark.

You are getting dangerously close to the limits of the stock fuel injectors at 16 psi on that turbo and stock AFRs, however. Fuel cut certainly isn't outside the realm of possibility.

 

[turbo2g111]

I hit fuel cut when my boost controller fell apart (I found out later I was pushing 24 PSI on a T25...), and it definately gives you a jolt. If it is fuel cut, you can do one of two things. The not so fun fix is that you can turn down the boost to a level where you are sure that your fuel system can handle it. The other option is to upgrade your fuel system with new afr, new injectors, a new pump, fuel management system, etc. If your computer is pulling that much timing, is it because you are experiencing knock? Is your XS intercooler able to cool efficiently enough to reduce knock?

 

[MrBoxx]

http://www.dsmtuners.com/forums/showthread.php?t=186971&highlight=fuel+cut

The not so fun fix is that you can turn down the boost to a level where you are sure that your fuel system can handle it. The other option is to upgrade your fuel system with new afr, new injectors, a new pump, fuel management system, etc.

Fuel cut is not caused by a lacking fuel system or the car running into the limits of the fuel system. Rather, it's an issue of the ECU seeing too much air and cutting the fuel supply off. Boost leaks are probably the most common cause.

As don mentioned, a log would help. I'm also unfamiliar with pocketlogger, so unfortunately I can't help you out there.

 

[donmagicjuan]

Thanks for the link to the information, Eric. I didn't mean to imply that fuel cut is called for when the fuel system is being pushed beyond its limits; however, if turning up the boost on stock injectors and a stock tune, fuel cut can be reached without any boost leaks. If memory serves this will coincidentally occur at some value around 100% IDC, give or take.

 

[MrBoxx]

if turning up the boost on stock injectors and a stock tune, fuel cut can be reached without any boost leaks. If memory serves this will coincidentally occur at some value around 100% IDC, give or take.

I believe that's correct as well. Now that you've brought that up, I'm interested to see what a log will show for IDCs in this case, especially since ryno appears to have an adequate fuel pump and AFPR, but is still running stock injectors.

 

[ryno]

Im purchasing 650's as soon as i can get my hand on some. What i ment by pulling timing was really thats its just reading 25-35 degrees timing at WOT. I just cant figure how to read this damn logger. Cant get it to just show a table or something. I cant find any boostleaks at all. A couple at the welds from the FMIC kit(thanks xs) but thats it. I dont hink thats gonna cause this. So am i experiencing fuel cut or something different. I am on the stock tune. But i didnt think that would matter with the stock injectors. im also looking to buy a 255 and see if that helps. Maybe Im just running lean on the top end? But why is 1st and 2nd gear pulls harder and smoother?

 

[spyderturbo007]

When you say that you can't figure out where to plug in the logger, what exactly do you mean? Are you talking about hooking it up to your computer in order to extract the log? If so, you need a serial port on your PC, or a USB sync cable for your Palm. You can get away with serial to USB adapters, but it's pretty much hit or miss with those things.

As for viewing the log, you need to download PLViewer from the pocketlogger website. I'm feeling frisky today, so I'll see if I can find you a link.

EDIT -> www.pocketlogger.com/viewer/dsm/PlViewer.jar

Beware if you are using Internet Explorer, you will have to make some modification to the file that you are downloading. Internet Explorer, for some reason or another, will think the file is a zip file and you won't be able to run the program. You will have to do the following (Windows XP)

Go to Tools -> Folder Options
Click the view tab and uncheck the "Hide extensions for known file types".

Then find your file and change the extension from .zip to .jar

Oh, and make sure that you have the Java platform installed, or the program won't work.

http://java.sun.com

Damn, I'm tired after doing all that work......I think I'm going to go take a nap, just don't tell my boss.

 

[ryno]

Im downloading those now. Ok so i need the usb to serial adapter. Where can you buy one? Like radio shak?
Thnks for all the help! I still want to figure this dang problem out.

 

[MrBoxx]

If it's a DB9 pin RS232 serial interface, I would recommend the Keyspan adapter, which is what a lot of DSMLink people use, including myself. It's about $40 and works flawlessly.

 

[ryno]

Update, new safc2 and FIC 650's are on the way. They promised they could help, .

 

[jibberishballr]

I am having the same problem and just had an idea. Could it be because i have my lines hooked up the old way where the bov doesnt have its own line. I know its not the correct way but works and i will fix it soon but could this be causing it.


Heres how im set up right now:

Wastegate-MBC-BOV-Intake Manifold

I know the correct way i just was wondering if this could be the solution to my problem?

 

[ryno]

When you say that you can't figure out where to plug in the logger, what exactly do you mean? Are you talking about hooking it up to your computer in order to extract the log? If so, you need a serial port on your PC, or a USB sync cable for your Palm. You can get away with serial to USB adapters, but it's pretty much hit or miss with those things.

As for viewing the log, you need to download PLViewer from the pocketlogger website. I'm feeling frisky today, so I'll see if I can find you a link.

EDIT -> www.pocketlogger.com/viewer/dsm/PlViewer.jar

Beware if you are using Internet Explorer, you will have to make some modification to the file that you are downloading. Internet Explorer, for some reason or another, will think the file is a zip file and you won't be able to run the program. You will have to do the following (Windows XP)

Go to Tools -> Folder Options
Click the view tab and uncheck the "Hide extensions for known file types".

Then find your file and change the extension from .zip to .jar

Oh, and make sure that you have the Java platform installed, or the program won't work.

http://java.sun.com

Damn, I'm tired after doing all that work......I think I'm going to go take a nap, just don't tell my boss.

I did exactly that! but as soon as I got it downloaded, im lost.
there is the plviewer folder. when i click on that it goes into modules and viewer folders, then each of those have like 15 folders, which ones do I do the extension change too? Also how do I do a extension change? I downloaded java also. Pleae help me, I know nothing about computers!
thanks

 

[spyderturbo007]

Pleae help me, I know nothing about computers!
thanks

No problem. I'll try to lay everything out step by step. I'm going to assume that you saved the program (PlViewer) in your "My Documents" folder. If you saved it somewhere else, just substitute that folder name everywhere I write "My Documents".

1. Open your "My Documents" folder by double clicking on the folder located on your desktop.

2. In the menubar at the top, click on "Tools", then click on "Folder Options".

3. Click on the "View" tab in the window that just opened.

4. Scroll down until you see a checkbox next to the words "Hide extensions for known file types". Now uncheck that box.

5. Click "OK"

6. Locate the file called "PlViewer.zip" and right click on the file one time.

7. Change the name to PlViewer.jar" and press "Enter".

8. You should now receive a prompt say something like "Changing extensions may make the file unstable, do you want to continue" or something along those lines. Press "OK".

9. Double click on the file now named "PlViewer.jar" and the program will open. Provided that you have already installed Java. If you haven't installed Java and need some help, let me know.

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