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

 

[jibberishballr]

Anybody know if my problem could have to do with this?

 

[Z32]

Just installed my FMIC(SBR Race Core) with an HKS SSQV Recirc, using a 2g Maf. Well everything seemed fine until i went up on the interstate and everytime i step on it enough to start boosting and let go off the gas, the car bucks like fuel cut. I'm quite clueless as to what it could be as it only does it during highway speeds. Never had fuel cut issues before and isn't my keydiver chip supposed to somewhat help me in that? Anyone out there have any ideas?

 

[1stGenRocks]

Did you do a boost leak test after the install?

 

[Z32]

Not yet, but probably should

 

[Z32]

Checked for boost leaks today and found a leak on my Throttle Body which i already knew i had, but i never had issues with that before FMIC and now i do? Dont understand.

 

[jdhutchin]

When you let off the gas, the ecu does cut fuel. If it sees the idle switch is on and it's above 1200rpm, it cuts fuel to help with engine braking, etc.

 

[1997turbodsm]

i've got a 1997 eclipse gst. Motors good with 180 compression. Upgrades are Evo III 16g, Injen Intake, external Gate, Full exhaust(minus o2 housing still stock). got NGK wires and plugs Got the Greddy Profect 2. Been playing with it and got it tuned where i was running 13.5psi. HOLDING GOOD. Go to turn it up and starts holding 14.0-14.4 and then it feels like Fuel Cut is kicking the car back. Any one got any clues?



My fuel system is stock.

 

[blackbyrd]

Any one got any clues?

Yeah..

My fuel system is stock.

haha. I know 14.5psi isn't that high to be hitting fuel cut, but the 16g is a slightly higher trim. Do you have a logger? can you get some details on whats going on at this time? Have you replaced your fuel filter?
I'd think about getting a walboro 190 and rewire it for starters.. Then start thinking about some injectors/tunning device.

Are you an automatic by anychance?

 

[oldman]

Boost leak test.

 

[blackbyrd]

^^Nice I missed that one.

 

[1997turbodsm]

no i do not have a logger. Never really messed with it. I really dont think i have a boost leak b/c it holds for a good second or 2 and then does it. Once it kicks back it holds it again for another couple of seconds. i've got a AFR gauge(not wideband) and it says rich but you know how that thing is. i'm spiking about 15.5 then holding around 14.0 until it kicks back?

 

[1997turbodsm]

Do you think that adding fuel(injectors,pump,AFC) would fix the problem all together?

 

[DSM-Talon-John]

how many miles are on it, I just had the same problem. So ill give you the run down on what this guy did for me. First he replaced the fuel filter, cleaned and gapped the plugs, checked the plug wires(problem there). So just because your car. Since you got new plugs and wires I suggest a new fuel filter and cleaning the injectors. Then again your running the 16g with a stock fuel system.

 

[1997turbodsm]

Also how would i go about getting a LOGGER? do you have a link?

 

[donmagicjuan]

You'd be surprised how big of a leak a turbo can overcome. You really need to do a boost leak test, as a leak is the number one cause of fuel cut. Those stock injectors are likely being maxed out as well, so it would be a very good idea to upgrade your fuel system, especially if you don't have a logger.

 

[1997turbodsm]

i just tripped 82000 today. i'd like to hold like 16 until i get more fuel. I've HELD 19 b4 i changed the spark plugs and put the external wastegate up there. I had a Boost Creep Problem with the stock wastegate that comes with it. it would to to about 12 then creep to about 20 so i stopped that problem with the external wastegate. Another reason i dont think it is a boost leak.

 

[1997turbodsm]

i'll do a boost leak check on it sometime this week. Just to make sure though. until then i'll just drive the car easy.

 

[1997turbodsm]

how many psi can you run with the 16g with the stock fuel system. i thought i heard about 17 but idk. maybe i heard wrong.

 

[DSM-Talon-John]

It shouldnt be fuel cut at 14 psi, I doubt you have fuel cut. Explain what it does in a full explanation.

 

[oldman]

You don't think you have boost leaks because you do not understand what causes a fuel cut. Fuel cut has nothing to do with running out of fuel or your ability to deliver fuel, fuel cut is designed to guard against run away boost (defective wastegate) and is trigger by excessive air flow. You're able to hold boost for a little before fuel cut because higher rpm flows more air. The reason boost leaks are the number one cause of fuel cut is because you're losing metered air causing a spike in air flow reading at the MAF, then fuel cut is triggered because your ECU thinks your wastegate isn't functioning and boost is spining out of control.

 

[1997turbodsm]

ok i was boosting on the car and i was watching my boost controller it spiked to about 15.5 then it was holding at 14.0 and dancing around 14.1,14.2,14.3, but not really creeping up b/c it was holding back and forth around those. Then once i get to about 4500-5500 rpm it just feels like fuel cut. from inside the car you can hear the wastegate opening then it stops and the car dies(front end to the ground but still runing) then picks right up again with in seconds. sounds kinda like the car misfired. What should my spark plugs be set to. i've gapped then around 28 hundreths.

 

[1997turbodsm]

i'm going to check all my hoses in the morning and make sure that they are all tight. then do a boost leak test. i think i know exactly what the problem is. I believe your right with the boost leak b/c of my top intercooler pipe. Thanks for all the answers and quick replys. any ideas on what psi i could do safley. 16?

 

[96TSiAWDBLK]

I'd say 15 would be safe.

 

[1997turbodsm]

nice. 15 is what i'll do until i get fuel upgrades.

 

[DSM-Talon-John]

if it caused fuel cut your gonna have reset your computer by detacthing the negative terminal for 30 seconds after you fix it, I believe so anyways.