Fuel Cut Question

[Justin]

I feel really dumb asking this because I have a fair grasp on most aspects of my car but I want a definition I am comfortable with.

I know that fuel cut does exactly that. Cuts fuel. I also know that it occurs when the output of the KV AFM pass's a certian frequency (1400hz or somthing?) now, does this occur because the ECU is smart enough to realize that any amount of air over 1400 hz (or whatever) is more air than the stock 440's can produce fuel for?

 

[IJ.]

Good question Justin!

Don't feel "dumb" I'd like to know as well!

 

[CTsupra]

i don't really know, but that would be the jist of it.

 

[Bishop92t]

~1499hz is the cutoff frequency, but it's not as simple as that. Other aspects such as throttle and air temperature make a difference as well. It's not necessarily the limit for 440cc injectors, it's just the safety limit that Toyota thought was needed.

 

[Justin]

Can one of my three displays on my e01 show the freq. of the kv signal? right now i have it set to boost/rpm/throttle pos. but i'd like to be able to see the kv signal!

 

[Justin]

Bishop, an others. is 1499 the cutoff frequency because the ecu knows that the fuel injectors cannot produce enough fuel, or the afm can't flow enough air?

 

[kulangflow]

I know that fuel cut does exactly that. Cuts fuel.

Does it really cut the fuel, or does it just cut the spark?

I remember reading something to that effect once upon a time on the SOGI list e-mails.

 

[IJ.]

Kung: It would have to shut the fuel off as cutting spark on a Cat equipped car = bad!

 

[kulangflow]

HAHAHAHAHAHAH!!!! :icon_idea

I guess it would help if I used my freakin' brain!

Thanks IJ ....

 

[IJ.]

LOL Kung!

My standalone has a rev limiter that cuts the fuel but as the car has dual fuel Gas or Propane it has no way of controlling the revs when on Propane!
(I know this seems a bit off topic)

This is the only reason I'd given it any thought at all!
Old school rev limiters used to cut spark but with Cats ya can't so I figured FC in a Supra has to cut fuel as well!

<Abe Simpson rambling mode engaged>

 

[drjonez]

Bishop, an others. is 1499 the cutoff frequency because the ecu knows that the fuel injectors cannot produce enough fuel, or the afm can't flow enough air?

neither, it's to prevent engine destruction due to stupidity or other problems (think broken WG).

 

[IJ.]

neither, it's to prevent engine destruction due to stupidity or other problems (think broken WG).

:yelrotflm

 

[Bishop92t]

The e-01 when connected to the e-Manage can display KV signal, otherwise it's limited to boost, rpm, throttle, and anything you've got connected to the external harness.

As for why Toyota placed the limit there, as I explained earlier it's not really a limit of any one particular part. It's really a collective limit of all the stock crap - injectors, afm, turbo, exhaust, intercooler, etc. When you go past FCO you basically pass the safety point. You may get away with 13 psi, you may get away with 18, every car is different. That's why gauges are important in monitoring engine health.

 

[Justin]

Nice, I'm definatly going to put KV Freq on display for a while to watch that :-D



okay, I understand