Article: What is Fuel Cut?

that1guy

New Member
Oct 5, 2011
15
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Lansing MI.
Are there other benifits to running the V8 AFM? I currently have one on my 91, and the idle sux. It's very hard to start, and I was thinking of switching back. I was also told to get the matching injectors, and it would cure this problem. I am just curious to know the benifits to this other than being able to turn up the boost before I make the decision to switch back.
 

Victor Charlie

Supramania Contributor
Aug 18, 2009
161
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0
Ann Arbor
1) How does a wideband tune overcome fuel cut? I'm working with lexus afm, 650 RC injectors, all the other usual intake and exhaust flow options except I have stock manifold, refurbished stock turbo and throttle body. Have zeitronix wideband, E-manage ultimate not yet installed -researching how to use it. Doesn't the ECU have the same limitations and fuel cut regardless of piggyback output, or will the emanage also modify the input to the ECU? 2) I can build a circuit to divide the AFM output frequency by a variable amount. Will this, combined with the emanage, help in tuning more safely than just eliminating fuel cut, or is it either dangerous or redundant? Thanks. I know this is an old thread, so I have to be patient before anyone notices it to comment, but I hope these questions are of general interest for future readers.
 

Poodles

I play with fire
Jul 22, 2006
16,757
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42
Fort Worth, TX
It won't remove fuel cut. The only way to do that is with a standalone or FCD (even on a standalone, you want to have overboost protection). It will raise fuel cut because you'll pull fuel (basicly lowering the AFM signal) because the stock tuning from Toyota is so rich.

I wouldn't divide the frequency, too much hassle and risk of harm. Remember, without timing control, messing with the AFM signal can do dangerous things with timing.
 

Victor Charlie

Supramania Contributor
Aug 18, 2009
161
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0
Ann Arbor
Poodles;1893360 said:
It won't remove fuel cut. The only way to do that is with a standalone or FCD (even on a standalone, you want to have overboost protection). It will raise fuel cut because you'll pull fuel (basicly lowering the AFM signal) because the stock tuning from Toyota is so rich.

I wouldn't divide the frequency, too much hassle and risk of harm. Remember, without timing control, messing with the AFM signal can do dangerous things with timing.

The HKS FCD for the MKIII is no longer being made! The Supra store and Horsepowerfreaks both said they have no source for it or for any other option to accomplish the same goal. S.O.L! So unless you can score a used one, is it correct to say that power gains even with a piggy back ECU are limited to the amount you can increase effective fuel cut with the lexus AFM? Of course swapping the ECU for a standalone is an option, but I've heard it may not be as driveable in varying conditions as the stock ECU.

With my huge intercooler and stiffer wastegate spring, I am hitting fuel cut all over the place without the lexus AFM mod currently installed. I'm having doubts that the lexus will be enough to overcome this completely. Hopefully Jon will have the modified stock ECU in production soon, which will make the FCD irrelevant.
 

simmi

Banned
Feb 14, 2013
25
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Rajathan
Hi, The fuel supply is cut to the engine, Its a fuel cut, ECU monitors things such as air:fuel ratio, rpm, temps, boost pressure, Basically, it knows how much fuel it needs and how much it is throwing through the fuel injectors. ECU basically says Hang on, if you run the boost any higher without more fuel, bad shit is going to happen" and it then cuts the fuel to the engine entirely to prevent it running lean and causing detonation
 
OneJArpus;1624282 said:
How else could i avoid FC with my setup? 1.5JZ 550's, Walbro, AFPR, MPT61 Turbo and SAFC to tune. (Version 1).

SAME QUESTION, ANSWER IS, IT IS SAFE TO RUN THE HKS FCD IF YOU HAVE THE FUEL AND AIR FLOW EVEN WITH THE FUEL FLOW. 550cc + WALBRO + Lexus AFM + HKS FCD = EVEN... More Fuel = Rich... Moniter with AEM Uego gauge ! There you have it, safe!
 

Poodles

I play with fire
Jul 22, 2006
16,757
0
0
42
Fort Worth, TX
spainobain1234;1963588 said:
SAME QUESTION, ANSWER IS, IT IS SAFE TO RUN THE HKS FCD IF YOU HAVE THE FUEL AND AIR FLOW EVEN WITH THE FUEL FLOW. 550cc + WALBRO + Lexus AFM + HKS FCD = EVEN... More Fuel = Rich... Moniter with AEM Uego gauge ! There you have it, safe!

1) quit with the caps lock
2) you're 100% wrong