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

 

[Quasimondo]

If you're still experiencing fuel cut, then you did not get all of your boost leaks. Do the test again, but this time have a bucket of soapy water with you. Get the entire intake system wet, from the filter (but not the filter iself, obviously) to the throttle body. When you pressurize the intake, the telltale bubbles will point to the leaks. Did you check your intercooler as well, you could have a leak at one of the fins caused by road debris. What about vacum lines, a torn line will be just as much of a problem.

 

[AHALLA05]

well i finally found the problem with the car. I borrowed my friends ecu and tried it in the car and it runs great.Obviously i did something wrong when i resoldered in my new capacitors. Could it be my capacitiors that i got off of ebay, when i changed them i noticed that they were smaller than the stock ones but tmo`s webite listed the right ones and they had the same # on the capacitors as the website`s.I know i soldered them in the right spot the right direction too. does anyone know enough about ecus that they could help me.The car runs completely fine except for the cut out at low boost.Fell bad for the friends ecu that i borrowed his went bad on the way to school this morning because of his caps, luckily i had the tools and my ecu, dont know what im gonna tell him yet

 

[oldman]

Once the capacitor leaks, it's possible that the board has already been damaged. Pm steve, the ecu expert/DSMwiseman, he has fixed two ecus for me already. Good luck.

 

[steve]

Could it be my capacitiors that i got off of ebay, when i changed them i noticed that they were smaller than the stock ones

All the capacitors are smaller than they were 10-15 years ago. Having put in a couple hundred sets in I can assure you that that's not the problem. More likely that you failed to repair the damage caused by the old ones leaking. I see a lot of ECUs that people tried changing themselves and still have problems. I see a lot of "Professional" repairs too. Now I know why they put stickers on the case so you can't open them, they don't want you to see how ugly and poor their work is.

Unless the board is seriously burned or one or more of the chips are bubbled from a voltage spike then ECUs are usually repairable, but whenever you have capacitor leakage you have check everything to make sure there aren't any almost microscopic opens in circuit traces.

Steve

 

[AHALLA05]

how much would u charge to get a non eprom redone and an eprom redone with a chip.Both need new caps and the eprom needs socketed and a stage 1 chip.I saw the prices on the website but i didnt know about labor.So just and estimate for both if you could thanks.

 

[pholic]

Alright, heres my problem. I have a AWD 90 talon, from this point on I will refer to it as "money pit". The "money pit" has had the same problem for three owners now. It runs absolutly awesome for 3 minutes after start up, ive timed it. From what ive read on these forums, that is when the computer switches from closed loop to open loop, or vice versa. Whichever one is the one where it does not pay any attention to the sensors and runs off default values in the CPU. After 3 minutes, it declines in its performance significantly. After about 10 seconds, you cant give it more than about 25% throttle without it cutting out real bad, backfiring, and acting like its going to blow up. Here is the tricky part, at one point, when I was running out of ideas, I hooked up a switch to the fuel pump. When it starts cutting out like this, I can turn the fuel pump off and back on real quick and its good to go for another 20 or 30 seconds.
Now before you get any ideas, here are the things that have been replaced in the car in an attempt to fix it. Three engines have graced the "money pit", three different ECUs, 3 different MFIs, 2 complete wireing harness, atleast 2 sets of sensors, all of them, 3 fuel pumps, 2 fuel filters, minus one Catalytic convertor as of a few days ago, new downpipe also, Pretty much everything but the gas lines going from the tank to the engine, has been replaced. I personally have sunk 3 grand into the "money pit" to fix this simple problem. Its just such a good money pit, because it runs great for a few minutes before it shits out. Ive tried unplugging every sensor, with no change, it throws no codes when all are plugged in. Remember before you answer, it has had the EXACT same problem with different engines, fuel systems, and electronics. Fire at will, because im completely at a loss finally, after just replacing the wireing harness. That was my last idea.

 

[pholic]

So I take it no one else has a clue either?

 

[1Gtuner1G]

Howdy, I just bought another talon, a 1992 TSi AWD. The motor is completely stock other than a K&N air filter and 3 inch cat back exhaust. My question is, is stuttering and then fuel cut on occassion normal or is something seriously wrong with my car? Thing is, sometimes it does it, then sometimes it won't. It is kinda like a chance thing. about 50% of the time though.
thanks

 

[oldman]

If you're 100% sure you hit fuel cut then check for boost leak. If you're not sure, check the plugs and wires as well. You should give it a complete check up like leak test, compression test...etc then a complete tune up before you go crazy with it.

 

[Screamin Eagle]

with an almost completely stock car, i doubt you are hitting fuel cut. Check for boost leaks. That was my culprit. If you have no leaks, and are still having problems, take out the lower honeycomb in you maf and back out the screw.

 

[1Gtuner1G]

Hey thanks... I am pretty sure I have a few boost leaks here and there but it sure does feel like fuel cut the way it just stops and almost jerks you outta the seat
I'll try the boost leak test as soon as I search and find how to do it exactly.

 

[oldman]

I'll try the boost leak test as soon as I search and find how to do it exactly.

http://www.vfaq.com/mods/ICtester.html

 

[1Gtuner1G]

Hey thanks
Another question, would a really really worn clutch make it do this too? like say around 5k just stops accelerating and free revs almost to the limiter?
NOTE: again feels like fuel cut when that happens, but its not every time it does it like that. Its almost completely impossible to predict when its going to happen, sometimes it doesn't, and then sometimes it does it allll the time

 

[oldman]

would a really really worn clutch make it do this too? like say around 5k just stops accelerating and free revs almost to the limiter?

The clutch is slipping. Which gear does it? Worn clutch will starts to slip at higher gears and work it's way down, once 3rd starts to slip, you don't have much time left.

 

[1Gtuner1G]

It does it in 2nd gear and it did it big time in 1st...
My other talon had the gm maf and translator on it and one day it just stopped running right and bogging under boost and all that. Didn't figure the maf or translator was the problem but I transferred it to my new talon and it started doing the exact same thing as my other one... hopefully the translator isn't the problem and the maf is I suppose...

 

[bob123131]

I'm kinda broke is there any way to fix fuel cut besides dsm link. Also is it true the bigger the injectors the faster to fuel cut.

 

[dsm john]

with a walbro 255 and AFPR and SAFC i am able to run 18 lbs of boost with my turbo w/ no fuel cut

not sure of your mods since you don't have any fuel mods listed

edit : oh yeah , i got rid of fuel cut by leaning out at the rpms i fuel cutted at until it was gone

i have an EGT gauge though so i felt somewhat safe while doing this

 

[green machine]

i run a 16g now and the only fuel mods i have are an safc and a 190 fuel pump and my car boost fine at 17psi do to great tunning.an safc wont run you more then 200 or less in the classifieds for dsms.

 

[steve]

Fuel Cut is based on the corrected airflow measured by the ECU. Putting bigger injectors in and lieing to the ECU about the actual airflow to correct for the bigger injectors delays when you hit the trigger. DSMlink or a 2G upgrade EPROM disables the trigger.

Steve

 

[trbotaln]

HKS FCD

 

[4pistons]

You can delay fuel cut by wiring in a potentiometer (or a resistor) to the Barometric Sensor and Air Temp Sensor to fool the ECU into thinking there is less air drawn in. You can also hack the MAS to achieve the same thing. Of course this leads to a lean mixture so you must monitor things closely or install bigger injectors to compensate.

Rick - '91 GSX

 

[obee1595]

will a fuel pressure regulator fixed the fuel cut if not will someone please tell me?

obee :talon

 

[andymoraitis]

Just to let you know, be careful of double posting.

Andy

 

[project_tsi]

91 Laser FWD Turbo. Mods are RNR 3" turbo back, 3" Dejon tool inkake, 3"GM Maf and Maf Translator V2.01. homeade MBC, Autometer Boost gauge, etc.
-In 1'st and 2'nd the car will pull to about 6-6500 rpm, and in 3'rd, 4'th, and 5'th it will only pull to about 5-5500 rpm, then it either hits fuel cut or something else, i dont know. The car will hit about 5500, then make a popping sound or like it cuts out, but almost immediatly it "cuts" back in and will gain another few hundred RPM's, then continues doing this all the way to redline. Why does it happen sooner in 3rd-5th rather than 1st and 2nd? I pulled my plugs, and saw the car was running a bit lean so I increased the fuel at Mid and WOT about 1-2 notches hoping that would help, but alctually it makes the car "cut" sooner! Why, when I increase the fuel, does it make the car cut sooner, about 4-4500 RPM's. I dont want to really decrease the fuel b/c I know its running lean. Also I noticed that i set my boost to 15psi but it will creep all the up to 20 pounds, w/ a 14b. Please help. No bashing me if its an easy fix. Thank you.

 

[blcknspo0ln]

boost leak test...