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

 

[fwdeclipse]

Well my problem is that when the car hits about 4k it cuts hard ,then it will continue and cut again every 500 rpms . I cant seem to figure this out.I have no boost leaks, held 20psi for 30seconds.It seems like it started having these problems after I changed by tb shaft seals.Also i have a joe p mbc and it is running 18 psi of boost set all the way down.If i take the bc off it will run 11psi,it doesnt cut out but it sputters at high rpms.Before i put in the 190lph fuel pump in,the boost controller set all the way down ran about 14psi. Please help!

 

[weith1111]

Check you plugs. If you are sure it's not air or fuel, spark is the only culprit left.

 

[fwdeclipse]

I just put brand new plugs in it a week ago and that did not help.I gapped them at .30 is this wrong.Also im not sure if its not fuel related,pretty sure its not air related though.

 

[andytalon]

Fuel cut is caused by the ecu seening a large airflow value from the maf which works out to roughly 100% dudy cycle on stock injectors. If ya install 550cc injectors which are 18% bigger than stock injectors, then adj the afc to compensate for the larger injectors, you wont hit fuel cut untill you make up for tha 18% airflow buffer. idealy you should get the injectors, afc, and other ecu mods needed to run ridiculous boost levels without running too low on fuel or hitting fuel cut, hope that helps a lil.

-andy

 

[weith1111]

Plugs should be .028 but that should be the problem in that case. You sure you got the correct plugs? NGK BPR6ES?

Turn the boost down to 16.

You should be able to prevent fuel cut with your current setup. Do another boost leak test and push on all the pipes and stuff. It may not be leaking sitting still, but with the motor moving all over something may be letting air out.

 

[fwdeclipse]

I checked for boost leaks again and there is a tiny one at the top of the bov,not sure if its enough to cut out so bad. Also i have my mbc turned all the way down and it wont run anything under 18psi. If i take it off it runs 11psi,and still sputters a bit. I will regap my plugs and probably put new wires on and try that.

 

[weith1111]

If your MBC doesn't go under 18 you have a problem. Is it hooked up properly? Setting it as low as it goes should give you stock boost.

 

[fwdeclipse]

Yeah i figured that was an issue.Before i put the fuel pump in it was going to 15psi set all the way downWTF .Do you think it could be a bad mbc.I know for a fact its hooked up correct. I have one end to the wastegate and the other end is teed to the bov.

 

[dub2gsx]

Make sure your boost controller is hooked up right. Then check and see if your plugs are arking in the dark with a squirt bottle. Make sure your plugs are gapped to spec. .028-.032. When is the last time you changed your fuel filter? Did you rewire your fuel pump and if you did, do you have a good connection!! You shouldn't be running max on duty cycle on your 450's quite yet! If it is still hitting cut then ????

 

[awdthomas]

check the spring in the boost controler.

 

[fwdeclipse]

No i have not rewired the pump yet. I just got some new wires and im gonna put them on. Also i am not sure if it is actually fuel cut,but it feels kinda like that. I tried to change my fuel filter last night and it was a bi***. I could not get it off,but iam going to try again tomorrow night. I have another boost controller and im gonna see if it does the same thing. I have the plugs gapped at .30 and im gonna try .28.

 

[fwdeclipse]

How do you check for arking?

 

[ddavisaf]

What kind of spark plugs do you have?
Are you venting to the atmosphere (BOV)?

 

[Ludachris]

I always cringe when I hear people running 18-20psi with no logger and no way to control fuel. Without a logger, you can't tell what your duty cycle is at or if you're knocking.

Have someone drive behind you - when it cuts out, does it puff smoke? Does it cut out once really hard or a few times in a row? If it's multiple times, I'm would check for an arcing plug wire.

 

[dub2gsx]

How do you check for arking?

It's really easy, just go to a place that is really dark like your garage at night. Then get a squirt bottle and spray your plug wires with a coat of water. Then watch for blue sparks. They can be small with just one or two or they can be all over like a light show... If they do then get some new ones. Get some of your preference or just read up with the search and find which ones you like. I have the Accel 300+ Ferro-Spiral ThunderSport Wires or just get some at Autozone they all work!!

PLEASE get a logger!! If you love your car!!

 

[andytalon]

If I were you I would turn my boost down to 12 psi get a logger and afc or if you plan on going big in the future for plans get dsm link or whatever floats your boat, but you should not be running 18 psi with no way of seeing whats going on inside of your engine...

-Make sure you are not venting, if you are plug the hose back in place!
-Turn boost down till you can see whats going on, Get a logger!

Remeber one thing your power can drop off after a while when boost due to intercooler flow and intake temp. what you want to do when you have the proper logging equpitment is find the lowest boost that still feels stong. you might as well run just wat boost you need to make power rather than stressing the turbo and chance of detonation of pump gas.

I have heard you can run 18-20 psi on stock piping and stock intercooler but, I think you would be best to stay in 15-16psi range!

Good luck comeback to us when your ready!

 

[fwdeclipse]

Ok let me start with iam not venting to atmosphere, and my spark plugs are ngk bpr6es. I agree with not running 18psi,but that was the least my boost controller will let me run.So i just took it off and it runs at 12psi. The problem still persists,although its not nearly as bad but it is more like a bad sputter. When the boost is up it just hits a wall. I just installed new wires and it did not fix it. Tomorrow i am going to change the fuel filter and hope thats it. If thats not it what next?:

 

[fwdeclipse]

[

Have someone drive behind you - when it cuts out, does it puff smoke? Does it cut out once really hard or a few times in a row? If it's multiple times, I'm would check for an arcing plug wire.[/QUOTE]
Im not sure if it smokes,but i will have someone ride behind me. when the boost was up it was one really hard,then it would start to go again then cut hard again. With the boost down its more of a repetitive sputtering, like a small miss. But the rpms keep moving up.

 

[fwdeclipse]

Something i just thought about, that probably is not it but its worth a shot. I have one of those cheap piece of shit ebay bov . at 12psi of boost it sounds more like the hks ssq, and i have the top spring screwed almost all the way out.Probably nothing just a thought.

 

[andytalon]

Im not to sure but, is it the one that looks identical to the hks?

 

[dub2gsx]

Rewire your fuel pump! You have the 14b and it wants more fuel! The stock wiring isn't meant for higher psi and it needs to be a bigger gauged wire and go straight to your battery!! It's worth the $30-40. But before you do anything try to get a logger or at least barrow one from a friend! Are your plugs gapped to .028-.032!!??

 

[dsmsucks]

Yeah luda I hear ya. Then when the engine goes ka boom, dsms are bad cars?!?!?!?!

Man you need to turn the boost down to 16psi and look thru the about boost and fuel control

 

[1fstSS]

your probably cutting because your running stock fuel and spark curves trying to run 18psi, you realy need to have a logger when you get over 15. i had my laser cranked up too 18 and ran my logger and about crapped my self because the knock count was so high it actualy made me laugh (like 26-27.) next think i knew i was picking pieces of the motor up off the road. you realy need to do the rewire, its a cake walk and takes like 20 min to do. and i would suggest getting a SAFC, MAFT or something.

 

[fwdeclipse]

No my bov looks like a greddy.I dont know if any of you guys are actually reading my responses. I understand that i shouldnt run that much boost. My boost controller was broken and it ran that much boost for a couple pulls.I have bigger problems, it still runs like shit at 12psi.There is something wrong at all boost levels.Basically with 18psi it would cut,and maybe cause its just to much boost,but it sputters real bad at 12psi so could someone help with that.I am changing the fuel filter tonight and ill order a logger as well so i can show some logs. Thanks for all the replies.

 

[fwdeclipse]

Ok i changed the fuel filter tonight,and it seems to be running better at 11psi. I am going to get another boost controller and turn it up to 15psi and see how it runs then.I also ordered a logger.