What does fuel cut feel like?

[andydckent]

Hi guys!

A the last couple of times I've driven my VR-4 I have experienced what I think is fuel cut. When accelerating at lowish speeds but with hard throttle the car suddenly jerked and then continued. The best I can describe it is a bit like when one of the turbo pipes had blown off, except it didn't come to a halt. I have no such issues accelerating hard at higher initial speeds. I am boosting to usually 0.9 but sometimes 0.95 bar.

Thanks

Andy

[peter thomson]

That sounds like fuel cut Andy. You'll have to dial the mbc back a little bit

[andydckent]

Cheers Peter, will turn it down a tad later on. I think we may as well just abolish the forum and just have a pm Peter button

[aboo]

Thats what I do Andy

[elnevio]

Exactly the same here Andy. Drive around it! Use the gears up to the red line...

[andydckent]

Ok heres a follow up to the boost cut question. Does atmospheric pressure affect the boost level? ie When its raining does the car boost more than if it is dry? I ask because having reduced the boost and 'testing' the new level I did not have any fuel cut, but now, today in the rain it came back and the car boosted to 1 bar. Incidently, or perhaps not, it had been wet the last time it was getting fuel cut.

[elnevio]

It's probably cooler - so the air is denser. And yes, this makes it more susceptible to fuel cut.

The first time I hit fuel cut was about three months after installing my MBC, and on a chilly, foggy January morning!

[andydckent]

Thanks for the fast reply Nev. Looks like the valve will have to be turned down a touch more.

[starky]

Thats why I prefer EBC`s so I can have 4 settings to change to dependant on weather etc
I hate fuel cut only get it on really cold days with boost set to 1 bar but I'm one of the lucky ones who can run 1bar without fuel cut 99% of the time
Firts time it happens its a pant filling moment though.......

[AderC]

I've upped the limit on mine in my last ECU reflash. A bit of testing showed it will now cut at 18.5-19.0psi rather than 16.0-16.5, so I can run 1.0-1.1 bar without fuel cut

[Legnum]

Do maf mod and use mbc/bypass boost control solenoid

After these can boost > 1 bar without fuelcut. Before these cutted in 0.8 bar.
Lambda is still ok, maf mod does not affect a lot if any.

Modded before:
- 3" catback, downpipes, de-cat
- 600x300x76 intercooler
- panel filter
- mbc
- fuel pump (hot wired) + regulator
- PLX wideband
- ..

[GroundControl]

I think I'm going to have to dial back my EBC settings slightly, as I got this coming back from the mountain last weekend (and it was summer when I set the EBC up).

Booted it in 3rd (or was it 4th?) on an uphill passing lane, about 7 degrees outside, felt a slight stutter (misfire?) then quite a solid loss of power for a moment.

I have felt the stutter before under WOT, but not the 'hit' of the fuel cut. Maybe the plugs need looking at?

[Kenneth]

Could be plugs. Best to take a look at them first. Do you know how old they are?

[Subaru ETA]

yeah sounds like the spark is getting "blown out"

[GroundControl]

Could be plugs. Best to take a look at them first. Do you know how old they are?

They were changed just before I got the car (it had a big service then, cambelt, clutch, etc... I'm pretty sure plugs were on the list).

So that would have been, um... mid 2005 sometime.

[vr4-fan]

me car feel like fuel cut , when I run 14 psi , I things its the spark bad , 1 mounth ago 1 pinping out , and the car get smoke very very dark , that blown the spark plugs , beacuase the car sound like a gun PAF

[Turbo_Steve]

Yes. Sounds like it either your plugs or your leads need attention.
How are you monitoring ping / det?

[vr4-fan]

Yes. Sounds like it either your plugs or your leads need attention.
How are you monitoring ping / det?

when the pinping get out , the car turn off , only still power on , when I full trottre , and the smoke dark, i thing that broke me spark plug , and now when i up the PSI , have problem ,and litter detonation

[Subaru ETA]

now theres a good idea.... crank the boost up when its blowing smoke etc....

[apeman69]

now theres a good idea.... crank the boost up when its blowing smoke etc....

Sometimes it's difficult to come up with a new idea... something you just wouldn't think about on your own. That's the beauty of this friendly, top notch forum. There's always someone about to give you that little spark of inspiration that will fire your imagination. I'll try that, sounds good! or will it be
I can crank the boost up but how did I geeting blow smokes? Plees help me now. I paying for mumbersheep layter. (again!)