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

 

[Thebeast431]

You said the car was stock just 3 posts ago, but now its hitting 15psi ?????

 

[madman]

"I think that I was getting fuel cut because my FPR was stuck and causing more pressure than the pump could put out."

could this be my problem. i'm getting fuel cut after i installed my BOV and exhaust. plus i had a hi flow air filter and i'm running at stock boost w/ stock turbo.

people kept telling my that i couldn't get fuel cut with the stock turbo.

i thought i already need a larger fuel pump, but could there be something esle wrong?

 

[sjwelna]

Ok, so my gf and I decide to go for a drive a couple nights ago. As i was pulling away from a stop light, i shift into second gear, and it feels like the car is bucking a bit, but very noticeably. As in I was thinking to myself "wtf is this, it's not done this before..." I shift into third and it does it a little bit again. It was cool out (maybe like 28ish to 35 out), and I had just started up the car, so the engine was still cold. I WAS going easy on it, as I always do until she warms up. I was not boosting. As soon as the car warmed up, it didn't do it. Is this a case of fuel cut? If not, could it be plugs/fuel filter related?

Mod list is current, did the BCS restrictor mod last night, so i'm running about 15-16 psi on a stock fuel system, on the T-too small. (this shouldn't be an issue as I did the mod AFTER i had the event)

 

[TurBoGs-T]

Fuel cut isn't a sequence of bucking. It's a one very hard one that makes you thing that you just blew something. if its a series of bucking and you weren't on the gas too heavy it was probably sparkies and wires.

 

[garysever]

Make sure the gap on your plugs is alright. My talon did the same thing and that was the problem. Good luck.

 

[sjwelna]

Thanks guys, I didn't think it was fuel cut, but I was getting some "interesting" information when I searched. (i.e. conflicting)

I think I might just use this as an excuse to replace them, as I don't know the last time that they were replaced by the previous owner of the car....

Looks like a pair of NGK BPR6ES it is.....

 

[Defiant]

Be extravagant, and use two pair.

 

[Venom69]

I just put a Walbro 255 in my 1990 Talon , along with a RNR 3 inch downpipe with O2 eliminator and external dump. Im pretty sure the pump is causing the fuel cut becasue I have the boost set at 12 or 16 PSI and the boost will stop there for a split second then continue rising until it hits 20 PSI! I hit fuel cut because of the uncontrolled boost. Do you think I might need a fuel pressure regulator or just some injectors with an Intercooler.

 

[Coldandafraid]

you are hitting fel cut because your ecu thinks too much air is being sucked into your engine... not because of your newly installed pump. Get bigger injectors, and an AFC and trick your ecu into thinking less air is going in.

 

[leet]

I think you need to control your boost first, THEN worry about injectors and an AFC. Though an AFPR would be a good purchase as well!

 

[lord_gufi]

Ah the glory of boost creep.

Just get Safc, Rewire fuel pump and Bigger injecters, tune the Afc to the negatives to make the Ecu think less air is going into the engine.

I hit fuel cut also, I need bigger injectors BAD. When I uncap my exaust I hit fuel cut at 18psi =(

 

[Mcgee16]

Ok Im getting fuel cut at inconsistent times. Somtimes when im hard on the gas it will cut at 14 psi and then somtimes it will cut at 18 psi. I have read before that the MAF is what calculates fuel-cut. I think that it has to be more indepth than that. I hear of people installing larger fuel pumps and it helps there fuel-cut. The ecu recives imputs from multiple sensors like the 02's, MAF, IAT, TPS, ECT, And so on. With these imputs the ECU calculates Short and long fuel trims. So what im trying to say, is tricking the MAF with a SAFC the only correct way to raise, or help eliminate fuel-cut. Im just trying to make it so i can drive my car without worrying about my head slamming into my steering wheel.

Thanks
Scott

 

[jtmcinder]

Fuel-cut is triggered by air-flow. (The ECU has no idea as to how much boost you're running and it really doesn't care.) Air-flow is calculated by the ECU. The MAS only take a few measurements related to the mass of the air being injested.

I have no idea why someone would say that a new fuel pump would help put off fuel-cut. But, then again, I have no idea why people say a lot of what they say. And I'm a psychologist.

Yes, using an S-AFC can put off fuel-cut by lying to the ECU about how much air you're really injesting. DSMLink can not only do the lying for you, but can disable fuel-cut directly.

With all that said, are you sure that you're hitting fuel cut?

- Jtoby

 

[Mcgee16]

Thanks for the reply. And ya its fuel cut. So The MAF is the only thing that can tell the ecu to fuel-cut. So i need to upgrade my fuel system and get a safc, another question, How much boost can the stock injectors with a larger fuel pump and safc keep up with.

 

[Defiant]

http://members.shaw.ca/costall/ECUprimer/ECU_ch7.html

 

[AL92]

I hit fuel cut the other day with maft fuel cut swith off and then again with the switch on.Don't these maft things work .

What else should I do to get around fuel cut.Only was running like 13 psi.

I think I heard run bigger injectors and then set the car a bit leaner.?

Sending the ecu in miight be an option but fairly expensive option right now.

 

[boostedtalon]

Actually having your ECU tuned is way cheaper for us than most, 300.00 for stage 3 from Tecnomotive, these are the only people I would ever let touch My ECU, my buddy is considering sending his to a guy that does the same thing for his vehicle (92' toyota Paseo w/ starlet 1.3 turbo swap) they want 800.00 for a racier one:-/ Acckk . . go here and look it is actually an awesome deal, and you can have it as mean or as sedate as you want.

Technomotive

If I can ever find a junker to drive while I send mine in, or get a stock one to send in so I can drive my car still, It will be done ASAP to my car

 

[boostedtalon]

Fuel Cut sucks, and the above link leads to an awesome article, even if you know it all you should still read it, it is very good reading.

But anyway onto my point, if your fuel system is stock that fuel cut saves your turbo and engine when it works If you want to increase the boost and stop fuel cut you will need to add some things . . like fuel. If you do not want to go the safc route, I am seriously considering not doing an afc for 2 reasons 1.) I don't have a reputable shop close enough to tune it. 2.) If it is tuned wrong it will make your engine do awful awful things to itself. so this is my alternative Click Me, (you know you want to)

 

[swing lo]

I'm still hitting fuel cut, but only in 3rd with the #3 mode switch on.

I think i'm maxing out my injector's as well, but how do you solve that.

My geuss would be to lean it out.......Am i right. I think it also varies on idle-mid-and wot.

Can i get some feedback please.

 

[AL92]

The number three mode switch is supposed to turn the fuel cut option on so it don't fuel cut.But it don't seem to work.I am pretty sure I have newest version of the maft too.I think Mike should come on here and tell us why the fuel cut don't work.

And like I said above how can I be maxing my injectors with a 14 b at just above stock boost it don't seem likely.

I am not sure if hit fuel cut in what gear..think it was third also.

 

[swing lo]

Originally posted by AL92
The number three mode switch is supposed to turn the fuel cut option on so it don't fuel cut.But it don't seem to work.I am pretty sure I have newest version of the maft too.I think Mike should come on here and tell us why the fuel cut don't work.

And like I said above how can I be maxing my injectors with a 14 b at just above stock boost it don't seem likely.

I am not sure if hit fuel cut in what gear..think it was third also.

I think it has to do with you running the injector's to rich at a certain throttle position. i.e idle-mid-and wot.

 

[DSMWillyb]

I was maxing out my stock injectors on my 14b (450cc) w/ maft - that's why I said you 'might' be - sounds like you don't have a datalogger and that might be a good xmas gift to yourself

 

[unior]

Originally posted by madman
"I think that I was getting fuel cut because my FPR was stuck and causing more pressure than the pump could put out."

could this be my problem. i'm getting fuel cut after i installed my BOV and exhaust. plus i had a hi flow air filter and i'm running at stock boost w/ stock turbo.

people kept telling my that i couldn't get fuel cut with the stock turbo.

i thought i already need a larger fuel pump, but could there be something esle wrong?

You probably have a boost leak - no way should you hit "legitimate" fuel cut with those mods.

Your boost leak is allowing metered air to escape before it gets to the engine therefore the ecu thinks you are drawing in to much air when your actually not. www.vfaq.com make an intake pressure tester

 

[RyanDSM]

Hey, I have a 91 Talon AWD TSi. Stock turbo, MBC, 3" HKS Exhaust, not much else. I hit fuel cut at 4500 rpm every time I floor it or even give it gas (in any gear), and I cannot boost over 8 PSI. Aside from the MAF, is there anything else that could cause these problems? Has anyone else experienced this?

Also, I'm not sure if this is off or not, but it feels like I'm not getting the correct speed at the right RPM as I used to - 110mph is 4500 in 5th, is that right?

Thanks!

 

[IHeartTurbo]

Aight, since I've had the car I've been getting fuel cut at 5 grand no matter what the boost was set at. I never really knew what to do to fix it so I just said #### it and dealt with it. Now that I've researched, I think I've figured out everything I need to get to fix it. I had holes in the intercooler outlet so I JB welded them. That only made the boost leak worse because the hose wouldn't seal around it since I made it so uneven. So, I'm getting a new smic. Also, when taking the engine out, we noticed my knock sensor was melted. Obviously if the sensor is shorting out, that could be causing fuel cut, too. So, I'm getting one of those. Now, besides making sure I don't have anymore boost leaks, is there anything else I might need to check and/or replace so that my car will be running perfect when it gets back on the road?