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

 

[foreverinvayne]

See, the thing is not 10 minutes after it shut off, when we were messing around finding spark, the car did start on 3 cylinders, then again when the wire was put back on the spark plug... and it's been running fine ever since. No fuel cut, just a lil of the same misfiring at high rpms

 

[Thunderskull]

I have to agree. Replace the wires and plugs first so that you can rule that out. If you still have the same problem then it is probably your coil pack or power transistor.

 

[byebyev8]

yea just sounds like u broke a plug some how My car did almost the exact same thing

 

[MR2_Turbo]

PROBLEM IS SOLVED! well....so far so good at least


I did the air can hack and removed the silencer behind the MAS and haven't hit fuel cut since!!


Hope this can help someone in the future.

 

[RallyChick]

i did a search on s-afc's and a search on fuel cut.

equipment:
uip, 1g crushed bov, 8.5mm magnecor wires, ngk pluggs, 3" turbo back exhaust, K&N cone filter with 95' talon maf, rest is stock.

i do have a slight leak where the downpipe is but i believe it was still cutting out when there were no leaks. fixing that this weekend. the check engine light will come on when it cuts out. and stays on.

at half to full throttle it will cut out. usually around 3500-4500 rpms 2-5th gear. i don't normally get on my car, but when i pass someone or a jerk doesn't want to let me over and i do get on it i manage to hit fuel cut.

i know getting the gm maft setup or s-afc can help the issue. i want to go the s-afc route but someone told me i have to get a fuel pump and injectors for it to work. IMO both setups are mainly to trick the computer to thinking it's running less air flow than it really is, so i wouldn't think you have to get a fuel pump and injectors to use that. what can i do? what are your suggestions? Thanks

 

[karbon]

I've never had a CEL with fuel cut. My best advice is to get a pocketlogger and a cheap palm pilot, or some other such code scanner so you can tell us what code it's throwing. My advice until then is to leak test the intake. Also the MAF nor AFC won't help or remove fuel cut, it'll help you get there faster though, since it flows more air. If you took any of your honeycombs out, put them back in.

 

[pholic]

Ok first a little background information. I was the proud owner of a 90 Laser RS, loved the speed, hated the traction. Bought a AWD talon tsi for 400 dollars...that was 2 weeks ago...

The talon actually ran, but it would just fuel cut and die. Wierd thing was, if you started it up, and immediately kicked it down, it would run like a raped ape for about 5 seconds, then back to hittin a brick wall of fuel cut.

So I figure, hey Ill, fix this problem, have me 2 dsms, awesome! WRONG.

Installled a new fuel pump, fuel filter, injectors, fuel rod, fpr, basically everything to do with fuel. tried the computer out of my 90 laser, it helped alot, thing the Caps had eaked on the AWDs... After that, it would actually run for a few minutes before it would meet the brick wall of fuel cut. Wierd thing was, I could turn the key off and back on and immediately rip it on down the road for another minute or so. after about 5 days, the engine blew, threw a rod. Back to one DSM

So I take the engine out of my FWD laser, have the head milled and all the valves redone while its out of the engine, get it all back together, drop it down in the awd, and to my sadness, same thing happened. This is a completely differernt engine, and it still does the same thing, computer and all electronics are out of the laser. The only thing left is flue lines, and anything backseats back. Tonight i was brainstorming and hooked up a switch to my fuel pump. Now whenever it starts to cut out, which it does gradually by the way, it will start to cut at 5k, then 4, then 3,. then 2, and it will just buck. Only way around it is sometimes if i just barely give it throttle it will drive. Anyways I got sidetracked, I hooked up a switch to my fuel pump, and now, whenever it starts to cut out, i turn it off for a few seonds, not the car, and then i can drive like normal again for another couple minutes. Im only boosting 10psi, and the AWD still has a stock exhaust on it. As of tonight ive ran out of ideas. Ive checked every sensor, with the old blown up engine and the one that is currrently in there, the only code im getting is a knock sensor code, i unplugged that, still does the same thing, Im finally at my wits end and completely out of ideas. I had a 13 second fwd laser and now I have an AWD talon that only runs for minutes at a time. Tommarrow I think im going to drop the tank and check it out, but if anyone has any other ideas the the hell this could be, it would be greatly appreaciated. Even after drving the AWD for a couple minutes, Id never go back to my FWD, but this car seems cursed, Please help.

 

[RallyChick]

i had the code checked a good while ago but i can't remember the numbers, it was something about the air fuel i believe.. i'll have to have a buddy of mine, check it to get the exact code sometime this weekend.

 

[1bad92awd]

I have a friend with a 1g who hit fuel cut many times, but i have never seen a code for it. You might want to check it out at a shop, it might be something else. As far as fixing your fuel cut problem, the safc is a good tool to richen things up a little bit, also upgrading you injectors helps a lot to, even some 550cc's just to get rid of fuel cut.

 

[pholic]

Oh today it blew its head gasket, now it over heats. Now I have 2 Problems to deal with.

 

[pholic]

Damn you guys are worthless! No ideas what the hell is wrong? Atleast suggest which head gasket i should go with!

 

[oldman]

Did you swap out the mas and check the wiring/plug? Souds like my car when I forgot to plug back in the mas. Good luck.

 

[pholic]

Yes, this isnt the first time my friend and I have swapped motors, or taken them out, or rebuilt them. The engine is fine, it has to have something to do with fuel delivery from the gas tank. When I replaced the fuel pump in it, it looked very rigged, like the previous owner had messed it up, not a clean look at all. How much does vaccum ect effect how the engine runes? Remember, it will run perfect for a couple of minutes, WOT and all, until it starts to cut out. One flip of the currently rigged fuel tank switch and it runs fine again for another minute or 2. This did it before I installed the new fuel pump too. Ive sank over 1200 dollars in this so far with absolutely no change. Fuel tank is the only thing left. I just ordered a Mitsu oem head gasket since the autozone POS didnt hold up.

 

[RallyChick]

im getting over 600 in taxes back so i'll have to look into that.

 

[nellyb]

I had the exact same problem. I flushed my injectors, replaced spark plugs and spark plug wires. After that my car ran smooth. You may want to check your coils too.

 

[Quasimondo]

You have an intake leak that is causing the fuel cut. The leak is causing your turbo to spin faster than it normally would to maintain boost that is being lost through the leak in your intake. The mas doesn't know this, so with the extra amount of air that is being sucked in through an overworked turbocharger, it thinks that you're running an insanely high amount of boost. Once the karmen count is too high, you get fuel cut.

It's not an issue of a leaking downpipe (though you should get it fixed), it's not an issue of bad coils, plugs, or wires (though you should keep them in good condition), it's simply an issue of your mas seeing too much air pass through it because leaky pipes are pissing away your boost. Do a pressure test on your intake, fix the leaks and your fuel cut problems will go away.

As far as you CEL goes, post the code here. I have a program that has every obd2 code from every car sold in the us, I can tell you what it is.

 

[InjenTalon96]

ok i installed my 2g mas the other day, its all installed rite, start the car up, idles perfect, but as soon as i start to drive i cant get it above 3500 rpm, all i hear is the turbo start to spool and i look at my a/f gauge it its completely lean, now i heard this is because i dont have a afc and stock injectors and a stock f/p. i was told once i put a afc in i wont have that problem anymore, is this correct??

 

[oldman]

You need bigger injector and pump to supply the engine with the added air flow, then afc to tune. Put the 1g back on until then.

 

[InjenTalon96]

im just going by what i was told from some ppl from ccdsm....they said slap on afc, turn up the fuel a little bit, and go from there, then it will be even better when i get a walbro 255 and 550's

 

[oldman]

Well you can probably tune it with afc but you should need a logger, you will have to keep the boost down so you don't max out on the fuel pump and injectors. Until you get at least a afc, logger and the knowlege to tune, you are playing a very dangerous game. You're running lean without even a egt gauge. Do your self a favor and put the 1g back on for now.

 

[InjenTalon96]

oh shit dude dont worry, after driving down my street, i turned rite around and havent been driving it since, dont wanna take any chances of damaging it, since im at 15 pounds u think if i lower it it will run better, and ya i sound like a fool but i havent touched my manual boost controller in so long, clockwise less boost rite???

 

[Sil-Eighty SE-K]

Ok so now with my 3in DP and catback (no cat) N1 ex im now hittin fuel cut. I have an HKS Fuel Cut Defencer that I will be installing but all i have besides that is a Walboro high flow fuel pump goin in. What im wondering is will it be safe to run the fcd with only a pump upgrade and no injector upgrade/fuel controller? Obviously Ill be getting an safc or something of the sort sometime...but i wanna keep stock injectors for a while....i just wanted to ask before I go and do something potentially stupid. I def dont wanna lean out....

 

[Bailzz]

Do you have more piictures of that engine bay? Is that your car?

 

[Bailzz]

:laugh: Nevermind, I'm an idiot (and tired). Fo r some dummazz reason I thought that was an EVO8 engine turned Gosh.....I'm such an idiot

 

[andymoraitis]

Can you give us some more info with respect to what's been done other than the exhaust? What kind of turbo are you running and how many pounds of boost is it taking to hit fuel cut? With more info, we'll be able to help out a bit more.

BTW, unless you planned on adding a large turbo down the road, that 3" DP is what's causing you to likely creep and then hit fuel cut. A 2.5" DP would have been more than enough. In trying to answer your question, I would add the fuel pump upgrade and turn the boost down a bit to keep things safe until you can add larger injectors and an SAFC. Then you can add the FCD. That's just how I'd do it, but your mileage may vary.