Whenever I puch it, the fuel cuts out. thought if i got a pressure regulator i could turn the fuel up and delay the cutout a little or something....did delay a little, but thats it. It's annoying when i'm accelerating and the check engine light turns on for a second and the fuel cuts out. HOW CAN I GET RID OF THE FUEL CUT-OFF?!??
The HKS "fuel cut defender" can't be the only method of solving this problem is it?
I read somewhere that the fuel is only cutting out because the intercooler may have cracks in the passages and is allowing too much air in. <--can't really believe that
You need to understand how the system works. Fuel cut is actually a function of the airflow meter alone. It watches how much air comes in and will cut if it exceeds a predetermined safe level. Whether it gets to the engine or not does not matter...it just cares how much passes over the meter. This happens on a healthy engine at around 12 lbs of boost, and depends on the environment more than the car. Fuel cut is most variable based on temperature. The lower the temp, the lower the cut. Fuel has nothing to do with it, other than the computer shutting off the injectors when it happens.
Anyhow, the FCD is the worst way to get past it. Stay away. Far too many motors are scrap now because the factory computer has no fuel map to speak of beyond that point. You will lean and melt the pistons.
There are several options. MAF-T (mass airflow translator, settings for bigger injectors, just fools the computer as to the real flow to match the injectors capabilities), MAP-ECU (Manifold air pressure ECU piggyback, similar to MAF-T but uses a pressure sensor liek the old VPC), lexus/550 mod (airflow meter from a lexus GS400 uses the same electronics and a 25% larger body...550cc injectors replace the factory 440's, which again are 25% larger), and finally the discontinued, but still available used HKS alphabet soup (VPC, F-CON, GCC). Finally, most safe and functional, and most expensive, a standalone engine management system.
YOu need to do a ton of research as none of these options are plug and play. All require tuning to keep you from needing a new set of pistons.
FCO (Fuel Cut Off) normally operates at 12psi. SO a better question, is how are you reaching 12psi? If you've pulled the wastegate line, have a boost controller, or a number of other things then FCO is doing what it's supposed to. If it's a stock car, then you've got bigger issues.
The Greddy BCC (Boost Cut Controller) is a much better option, lemme copy & paste from mkiv.com:
Quote:
The reason that the MkIV owners recommend the GReddy BCC over the HKS Fuel Cut Defensor (FCD)and the Free Fuel Cut Defensor (FFCD) is simple. The HKS unit reduces the signal coming from the turbo pressure sensor at a fixed percentage, which means that all the data coming from this sensor is corrupt. The FFCD fixes the value coming from the turbo pressure sensor at something close to atmospheric by capping the pressure input to the sensor.
In short, the Fuel Cut (Boost Cut, etc...) is there as a safety measure. It's there because the stock fuel components cannot flow enough fuel to not lean out the motor. Therefore unless you've got upgraded injectors and then something to control them it's a bad idea to try and bypass it.
__________________
1988 Mk3 Turbo Targa - 17.5psi, 486hp, 494tq.
[img]http://www.**********s.com/supra/rsw_sig_stupidTN.jpg[/img]
Who came up with this 500px wide BS?
alright, I have a 92 MKIII witha boost pressure regulator(swear it's only turned up to 11), blow off valve, fuel pressure regulator and a couple other bolt ons. Is getting the 550's and Lexus AFM the next best step? If I have that stuff and turn the boost up a little, will the fuel still cut out?
What all is incorperated in a stand alone fuel management system?
one more thing I did that I read about is drilling the housing out and backing the adjustable afm screw out in order to open up the meter....would this work better if I close it more?
550s and Lex AFM are a much MUCH better method. Backing that screw out can lean it out. The 440s just aren't prepared to supply that quantity of fuel for that air.
Also, if you've got a Boost Controller that's just a valve type, it's probably hitting 12psi and hitting fuel cut. You should probably have a Boost gauge, like a true honest to god accurate boost gauge. That will make things much better.
__________________
1988 Mk3 Turbo Targa - 17.5psi, 486hp, 494tq.
[img]http://www.**********s.com/supra/rsw_sig_stupidTN.jpg[/img]
Who came up with this 500px wide BS?
I have a little 30$ boost gauge....I know it's not super accurate though. Been thinking about picking up a good Autometer.
Ok, so If backing that screw out does open up the air flow substantially, then could I just get by with injectors for now and put the air meter on later? Or would that be too much fuel, I could turn the pressure down...adjustable fuel pressure regulator?
It also depends where it measures the pressure. Turbo outlet pressures are higher than manifold. The boost controller is seeing 12 or so PSI, even if you have an accurate gauge reading 11 T'd into the vacuum line (enough air for fuel cut...again, it is air related, not pressure, so 12 is a guestimate...could be lower or higher depending on the weather).
The lexus/550 upgrade is designed to work together. Otherwise, you simply overfuel an already rich car. You still hit fuel cut, it idles like crap, and you actually make less power. Do them together. You also need to tune...it's not quite plug and play, and it is do at your own risk. Lean it out and boom...new engine time.
Would I need the walbro pump in order to keep up...or is the factory one good enough?
Know anywhere where I could find the AFM for a good price?
Can I buy nepon denso 550 low-impedence injectors at any parts store? I read somewhere that they are the factory injectors for like half of a year of some rx-7 model or something....
It works to a point, but your upper end boost, and the age of the pump is going to determine how far the stock pump will carry. Tune on the wideband and you'll quickly know where the pump starts to give it up. Some reports say 15 ish lbs of boost fuel delivery is about it, and increased fuel pressure may send the pump south faster than you want.
That said, if in doubt, replace it. The walboro is cheaper than a new stocker anyhow, and for the peace of mind, there's no sense on cheaping out here. adjustible pressure regulator will take care of rough tuning, dyno and computer for the rest.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
ToyotaNation.com is an independent Toyota/Lexus enthusiast website. ToyotaNation.com is not sponsored by or in any way affiliated with Toyota Motor Sales, USA, Inc. The Toyota, Lexus and Scion names and logos are trademarks owned by Toyota Motor Sales, USA, Inc.
Forum for all Toyota Supra generations.
getting rid of fuel cut
Linear Mode
