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

 

[DrDSMGSX]

Cool, that answers all my questions. I will be getting the new capacitors wednesday and I will report back here if it has fixed all my gremlins.

Thank all of you again for your help,
Dan

 

[steve]

Like Mike pointed out, just replacing the capacitors may not take care of the ECU's problems.

Take a close look at the surrounding parts and circuits for signs of corrosion damage.
Your pictures show damage to both C14 and C38 as well as the vias and traces around them.

Steve

 

[DrDSMGSX]

I will look it over carefully when i get the capacitors pulled out and make sure the traces look okay. I am just looking for any type of break in the trace right? I cleaned up as much acid as I could before I plugged it back in for now and it looked okay but I am no pro. When I get everything cleaned up, can i post pictures and maybe you can let me know how they look to you?

Thanks again,
Dan

 

[DrDSMGSX]

Alright, so I have made the repairs to the ECU and took some pictures. I am going to wait till later to post more info to see if it actually fixed my problems so people will know one of the possibilities to look at when they are experiencing problems like I was.

Thanks,
Dan

 

[mTALONm]

i hit fuel cut if i try to give it full throttle below like 4000rpm. the full boost starts at like 2700. thats where i hit the fuel cut except for the 1st gear. i tried 10 13 and 15 psi.
help please

 

[92awddsm]

Your best bet would be to test for boost leaks. Generally that is the main cause for fuel cut.

I also assume that you are still running the 14b@16psi, right? Has the mas been hacked(aka lower hc removed)? That should not hit fuel cut but if you are running something different, let me know.

 

[bojanglesracing]

check your mbc for leaks mine did the same

 

[Travi2506]

The easiest and probably the cheapest way you should start is by building a Leak Tester ... but that's just my opinion...

 

[GUY]

well so i got my new intercooler setup. and i still have that horrible fuel cut feeling around 4500rpms. some of you thought i had a bad boost leak, so i bought a new setup. and that fuel cut sorta thing is still there, so now every 5 days or so i have to reset the ECU. and this is pissing me off. the thing almost feels like a damn 2-step but while im driving. i will accelerate it will randomly hit a certain rpm point, and it just stops, motor is reving but the car is not moving any faster? Im not really even able to hit my powerband. and the car is all stock besides front mount and exhaust. stock boost level and all. i am thinkin it may have something to do with the MAF, fuel or some electrical crap. i was thinking if an HKS FCD will kinda bandaid the problem sice there is no way of removing fuel cut. its like im getting a premature fuel cut. The car has a new ECU in it. i know for sure my knock sesor is going bad...would that have anything to do with this though? let me know...thanks in advance

-steve

 

[RLx02]

when your fuel cuts at 4500 does it feel like you just let off the gas or does it feel like someone slams on the brakes?

 

[GUY]

feels like i let off the gas

 

[redl1nerpm]

Im not an idiot, and I hate when people beat on a car or rev it when the engine hasnt fully warmed up. However, the guy I bought my car from drove it cold and was an idiot. When he would hit it, it would cut out. After I bought the car and fixed some things and started driving it, it wouldnt cut out for me (bc i let the car warm up). Yesterday one of my friends drove the car and hit it when it was cold and it cut out.

So, my question is, is there something that tells the car to cut when the engine hasnt warmed up?

If not, what in the world would cause this? The car is stock.

 

[gthompson97]

i've never heard of anything that cuts boost because of a certain engine temp...hell, i've never heard of anything that will cut boost because of some outside factor. so it's like it'll build boost and then all of sudden lose all boost pressure, or it just won't build anymore? are you maybe hitting fuel cut?

 

[redl1nerpm]

well once it builds full boost at around 4k or so, itll just jerk and cut out

 

[obee1595]

i have a 92 talon awd wiht a 1.3 MAFT, i have fuel cut right now i got rid of it befour but its back again does any one know what i have to set on my maft to fix. i have the mode set to take off the fuel cut but i dont think it worked.

can someone help me please?

 

[steve]

Setting the MAFT to disable fuel cut is a really bad idea and they figured that out.
What it would do is not output a signal higher than what triggered FC. Of course that would cause you car to run lean since the ECU wasn't seeing the right air counts.

So track down the real cause, fix all the air leaks, put in bigger injectors and correct with the MAFT if your really flowing enough air to trigger FC, or get a EPROM ECU and get it removed for real.

Steve

 

[eclipse_20g]

It doesnt get any clearer than that.

 

[Deadly BlaZe]

Ok i know its not good, but is it really bad for the engine? I think i experienced it for the first time tonight. I was revving to 6k in 2nd gear and then suddenly the car just had a really violent jerk. I was so scared because i thought the engine blew or something but it was running fine still. I pullover and open my hood to check if everything is ok and i look at my boost controller....and the knob was screwed almost all the way in . I wasn't looking at the boost gauge when i was doing it but i'm pretty sure i hit well over 20 pounds since the car was pulling like a mofo. But anywy, did i hurt the engine in anyway?

 

[Thor06]

To be honest, I dont know why fuel cut could hurt the engine, but I think it does or atleast its not good for it. Boosting like that would be though, especially on low grade gas. You might run into some wicked knock at 20+ psi especially if you get the cheap shit. Really bad knock can royally #### your engine, but just one pull should do too much. Does it still run ok?

 

[Jimmy Jr.]

You tell us if you wrecked the motor. Blowing oil? Losing coolant? Heavy smoke? Clanking? Knocking? Look people, if you hit fuel cut or over boost and realizing it before you run over your crank on the highway then you're good. My point being, if the motor is shot you'll know.

 

[Hazard_tb3]

hi everyone ..i Have searched and found something on this but my case as a little different
ok well i have a stock 90 laser RS turbo and i have an idle problem
the thing is when i first start my car everything is normal but within a minute it starts the idle surge thing...you know ...when the RPM needle goes up and down without touching the gas ...ok ...well the thing is when it does this and i press on the gas it raises the RPM by about 1000 and surges stronger but slower like a second apart as i press the gas more the RPMs dont move any higher they just stay there idling between 1300 and 2000 ....i am unable to let the car rev in between 2000 and 3000 the only time it goes past 3000 is when i floor it then it jumps up .... so i have to drive really fast everywhere all the time ....i cannot cruise between 2000 and 3000. If i am driving and i let it drop below 3000 it shoots down to like 1500 and my car bucks real bad but it does not stall.... i have bought a new Computer for it but i have not put it in yet
chuy said you guys could help me
thanks in advance.

EDIT: ok i read a post and i unpluged my MAF and it didnt surge and it let me go inbetween 2000 and 3000 a was all happy then after driving it down the street it started sputtering and when i would shift to the next gear from high rpm'ing the gas would almost seem to cut off but it wouldent die

 

[shingevo]

check your BOV and make sure its vented.
could also be your idle sensor.
MAF?
throttle body could also be dirty.
a new ECU and a good tune can also help your problems.
good luck!!

 

[Hazard_tb3]

ok ummm my BOV is ok and my TPs sensor is to spec..and thats all i think that can do that....
i am leaning toward my MAF sensor
because when i unplug it it stops surge but gives me different problems... this stinks

 

[tbob2985]

i am starting to have the same problem with my 91 GSX. after it warms up it will idle surge from 1000 to 1500(up and back down again). Then it will stop. then after i drive for about five minutes the idle will drop to about 500 and seem like its gonna stall, if i try to drive during this it will buck and barely move until 3000. Someone looked at it and said it was the throttle body and that i need a new one. Are there any other suggestions? I tried putting new plugs and wires so far.

 

[Hazard_tb3]

Heres a video of my RPM activity.

http://www.filefactory.com/get/f.php?f=38f62ba1587644c39279991f