What exactly does Fuel Cut feel like?

[fourgsixthree33]

What exactly does fuel cut feel/sound like? I know what it is, but I am not sure what happens if I experience it. The reason I am asking, is because I have been dealing with a weird problem for awhile now.

The thing I am experiencing, happens when I am around 15psi. Sometimes a little before, sometimes a little after. It "feels" like the same feeling you experience an intercooler pipe popping off. There is like, a popping noise. Then I let off, and get back on the throttle. But if I am WOT, it will happen again. If I do not let off, the car will buck pretty damn hard.

If I turn the MBC down and run say...10psi, it doesn't happen. I did a BLT before my 6 bolt swap. My FIAV block-off plate was leaking. I did the swap and JB welded the block-off plate on, but it still happens around 15psi.

I have yet to perform a boost leak test because I removed the timing belt to fix an oil leak. It will be put back together tomorrow and I will get a BLT when I can (air compressor is in the shed, but there is snow in the grass so I cannot pull the car up to the shed).

About a month and a half ago, I turned the MBC down so it runs 15psi and I also swapped my injector plugs around as directed my the "1G CAS on a 2G" article. Drove it and this thing didn't happen. I was able to go WOT at 15-16psi steady. Then, it started happening again after a couple of weeks. But, not all the time.

Profile is up to date. Only fuel upgrade I have is a Wally 255.

 

[99ECLIPSEGSXDSM]

Fuel cut feels like your car hits a brick wall and it backfires. Do another blt and turn your boost down to 12psi until you have something to tune with so you can see whats going on. Get a afpr with that 255 also

 

[idkiliketurbos]

First time I hit fuel cut I was in 2nd gear at the drag strip, nearly hit the helmet on the steering wheel . When you nearly get whiplash, you'll know.

 

[GearheadJ]

Yep... Just picked my car up today and on my drive home.. I hit fuel cut :/ felt like shit... time for more fuel !!!

 

[Cdc1221]

You shouldn't hit fuel cut on a t25 at any boost level. Sounds like a boost leak

 

[erkitner]

You obviously are running into an knock situation. The obvious red flag was when you mentioned the boost amount. Low boost was good, higher was when you got your symptoms.

Fuel cut is exactly what it sounds like. But this is a safety measure to keep you from blowing your engine to kingdom come. Your knock sensor (if working properly) detects detonation/knock based off the vibrations coming off the engine block. Hence, it's location directly on the back of your block.

When it DOES detect significant knock, it sends signal to your ECU to cut ADDITIONAL fuel to your engine since adding more fuel makes the situation worse.

If you're running any sort of data-logging/tuning software, a proper tune will eliminate this issue. By programming the fuel maps at the point which knock is detected and cutting back some of those values, your knock sensor will never NEED to "cut you off" for being drunk and getting out of line.

I recommend DSMLink Version 3. Excellent resource for tuning, engine management and overall diagnostics.

Word of advice for now? Back off the boost until you get it tuned properly for the amount of boost you want to run. It'll save you hard times and headaches.

Cheers.

 

[99ECLIPSEGSXDSM]

You shouldn't hit fuel cut on a t25 at any boost level. Sounds like a boost leak

Think hes running a 14b. His time slip says 14b unless it was an old car of his

 

[Cdc1221]

NEGATIVE. When the Ecuador sees knock, it pulls timing, not fuel
Pulling fuel will make matters worse.

 

[Cdc1221]

Ecu*. My phone autocorrects

 

[CountryDSM]

.

I recommend DSMLink Version 3. Excellent resource for tuning, engine management and overall diagnostics.

It's what I use and it will overall make your car happy .

 

[erkitner]

NEGATIVE. When the Ecuador sees knock, it pulls timing, not fuel
Pulling fuel will make matters worse.

My bad. You are correct, Sir. I am retarded.
I'm going to go hang myself now.

 

[casperfast]

Violent bucking/ jerking. Somtimes backfire. X3 on the boost leak test

 

[Cdc1221]

My bad. You are correct, Sir. I am retarded.
I'm going to go hang myself now.

dont do that!

 

[AngelOfPassion]

Ecu*. My phone autocorrects

I am going to refer to the ECU as Ecuador from now on!

 

[fourgsixthree33]

Lol. Thanks for the replies people!

Yes, I am running the 14B. I threw out that lil excuse of a turbo T-25 awhile ago.

But yea, I do get thrown at the steering wheel when it happens.

Knock sensor is new, just replaced it during the swap.

I am going to get a BLT done asap, but do you all agree this is fuel cut? Just want to verify this so I know when it happens in the future.

I am going to tune using an EVO 8 Ecuador (!). My vendor on my site is making a plug and play harness to use the EVO 8 ECU in a 1g and 2g. I hate wiring. If anyone happens to be interested in the harness, feel free to message me.

Thanks for the replies!

 

[Cdc1221]

Hope you lnow what your getting into with that Ecuador (), and dont mind downtime with the car

 

[fourgsixthree33]

Hope you lnow what your getting into with that Ecuador (), and dont mind downtime with the car

Please educate me.

Will be tuning with ECUflash.

 

[Cdc1221]

Read this...
http://www.dsmtuners.com/forums/articles-tuning-ecu/347103-evo-8-ecu-2g-your-visual-guide.html

And the accompanying thread.

 

[Spanky_DSM]

This happened to me yesterday just after fixing some exhaust leaks.

Boost goes up to 15psi and when it jerks, and when it does, the boost gauge reads 0.

Mods are:
Evo 8 fuel pump
Stock fuel pressure regulator
Evo bov
intake
full 3 exhaust
18g turbo
and stock boost controller

It wouldnt do this before i fixed the exhaust leaks.

Before it would hit 15psi. drop to 12psi. and just surge up and down

 

[erkitner]

I am going to refer to the ECU as Ecuador from now on!

Me too!

 

[Spanky_DSM]

Should the boost gauge drop to zero or go down during fuel cut? That's what im mainly concerned about when this happens.

 

[TheFallenJosh]

Similar problem on my end. Just installed my hard intercooler piping from punishment racing a few nights ago, and started having problems. Did a boost leak test, everything is perfect now. But I still get that buck at WOT usually in 3rd gear. I'm on a T25. Only mods I have are the intercooler piping, 1g bov, BCS restrictor removal, and an intake. It normally boosts at 15psi, but spikes to 20 on some pulls, that is normally when I get the buck. So I ordered a boost controller to stop the spiking. Hopefully that fixes my issue until I get link and can put in my 650s and walbro 255. I'm assuming this "buck" I get is fuel cut like everyone is describing.

 

[Spanky_DSM]

wow 20psi? i thought the t25 was gassed out around 15psi.

Does your boost gauge drop when you hit this "fuel cut"?

 

[mitsubishimanic]

im going to say yes to the fuel cut if your pushing 15psi with no tune or afpr it is very likely your hitting fuel cut because the stock fuel system can handle a max of 16lb of boost. having a bigger turbo and having a 255 fuel pump and no way to controll the added fuel pressure could also contribute to your problem. id suggest turning down the boost and getting a afpr to controll fuel pressure and at least afc-r to tune with.

 

[Spanky_DSM]

im going to say yes to the fuel cut if your pushing 15psi with no tune or afpr it is very likely your hitting fuel cut because the stock fuel system can handle a max of 16lb of boost. having a bigger turbo and having a 255 fuel pump and no way to controll the added fuel pressure could also contribute to your problem. id suggest turning down the boost and getting a afpr to controll fuel pressure and at least afc-r to tune with.

Im running the evo 8 which is rated around 185lph and should be fine on the stock Fuel regulator.. so ive read.

But ill look into that manual boost controller to knock it down some extra psi since its creeping on the stock boost controller.