Fuel Cut, is it a good or bad thing???

[jdub]

my a/f's are reading 10. at wot so I am not hitting a lean condition. I am not going the maft pro route either as I have dealt with the original maft and for reason known to others I refuse to go maft. Lex/550's is tried and true and after that I will be going full standalone.


I do have an afpr set at 28psi hose connected so do you think I could up the pressure a bit to get me past fc?

Raising the fuel pressure will not help you where fuel cut is concerned.

The reason the Lex works is you are bypassing more air around the sensor and it's larger diameter. You are fooling the ECU into seeing less air than is actually being compressed and sent to the motor. The Lex will raise your FC to about 16 psi.

If you want to get more boost, you will have to go with a MAFT Pro or a stand alone EMS on a speed density set-up.

 

[jdub]

If you are at 10, you can turn the adj screw out on the afm, that will lean it down, and maybe prevent f/c, it just doesnt have as big of a bypass as the lex.Just take it a little at a time and watch the a/f.

On a stock AFM all this does is allow you to bypass air so the sensor does not sense it. The stock AFM's bypass is small compared to the Lex...you will lean the AFR a bit, but leaning out AFR does not have any affect on FC. The effect on fuel cut (due to the bypass air) of the the adjustment screw on a stock AFM is very small.

 

[Boost Lee]

Fuel Cut-off is your friend.
Fuel Cut-off whiplash is your worst enemy.
:icon_conf

True story.

BTW:
If FCO on a Lexus AFM is at 16psi...Then I need to consider MAFTPRO because I was hitting FCO usually around 16-18psi on the STOCK AFM (Depending on the weather and atmosphere itself).

How? I'm not sure. I've used 3 different boost gauges and my vacuum lines are all good so I know it's accurate...:icon_conf

 

[tookwik4u89]

Maft-pro ftw!

 

[chriso]

Maft-pro ftw!

I hit fuel cut at 16psi using the Maft Pro in Speed Density mode.....but then again, I'm not fully tuned yet.

 

[tookwik4u89]

I get 23 and I think I can do better.

 

[cnewingham]

you can get more than 16psi with the lex/55o/safc setup.

 

[jdub]

you can get more than 16psi with the lex/55o/safc setup.

With the electronic fuel controllers...yes you can. You are still "fooling" the ECU concerning the amount of air flow the AFM is sensing. You will need to be careful tuning it. More than one guy who has done it this way has leaned the motor out at high rpm and...BANG...detonation

On a stock ECU (no SAFC), the Lex/550 combo is good for an average of 16 psi due to the reasons I mentioned...some will get a little more, some less. IMO speed density is the way to go...why do you think Toyota went SD on the Turbo A Then you program your stand alone to protect your engine based on EGT, or knock, or RPM, or all of the above.

You can also get an FCD and eliminate it all together too.

BTW - if you were to post all of the mods to your motor and your capability to control fuel, it would have cut down on the amount of speculation posted in this thread. Specifics really help in answering a question.

 

[Nick M]

why do you think Toyota went SD on the Turbo A

Becuause it was homgolation for a track car. And a track car with known engine VE should not have things in the inlet track.

Street is a different story.

 

[jdub]

Nick - Are you saying that speed density is inferior to the Karmen Vortex in the USDM 7M motor? Or is it just a different method to do the same thing?

 

[shaeff]

FYI- i hit a 20+psi boost spike with the LEX afm, and didn't hit fuel cut. good thing i let off super fast!)

-shaeff

 

[jdub]

FYI- i hit a 20+psi boost spike with the LEX afm, and didn't hit fuel cut. good thing i let off super fast!)

-shaeff

Were you using a SAFC?

 

[Clifton]

my a/f's are reading 10. at wot so I am not hitting a lean condition. I am not going the maft pro route either as I have dealt with the original maft and for reason known to others I refuse to go maft. Lex/550's is tried and true and after that I will be going full standalone.


I do have an afpr set at 28psi hose connected so do you think I could up the pressure a bit to get me past fc?

Yopur fp is pretty low, any reason it's lower than stock? Get an fcd and be done with fc forever. If your afr is in the 10's there is now reason to go with lex/550 unless you are going higher later. You can make your own fail safe with a NC pressure switch if you want safety.

 

[jdub]

Yopur fp is pretty low, any reason it's lower than stock? Get an fcd and be done with fc forever. If your afr is in the 10's there is now reason to go with lex/550 unless you are going higher later. You can make your own fail safe with a NC pressure switch if you want safety.

28 psi is not low with the vac line connected. Take a look at the TRSM.

 

[Clifton]

I've checked 2, both were around 40 psi without vac and 35/36 with.

 

[jdub]

Ok...read carefully:

- The 1st set of FP is with the service wire connected...the system is at 12 volts, engine off...33-40 psi is the spec.

- The 2nd set of FP is with service wire removed (system at 9 volts, idle), vacuum line off...33-40 psi is the spec...40 psi is at the top of spec.

- The 3rd set is normal condition, no service wire (system at 9 volts, idle), and vacuum line on. That is the pressure I was referring to...28 psi is not low...23-30 psi is the spec. In fact, 35-36 psi is high under this condition...that can make you run rich...hesitation and studdering at high throttle.

 

[xXxICExXx]

Late-ish post: I think fuel cut is a good thing to experience for you but not for your car. Your car knows its limits, many drivers don't :icon_wink