defeating fuel cut with a diode?

[Branners]

copied from the Supraforums list...this is the last bit of the thread after various discussions about how the HKS and Greddy fuel cut controllers work....

 

My question is, has the guy got a point about putting the diode in line...?

 

The HKS FCD reduces the voltage by a constant percentage....therefore the output signal IS ALWAYS CORRUPT.

 

The Greddy BCC limits the voltage only, so it is ONLY CORRUPT WHEN THE TURBO PRESSURE SENSOR OUTPUT EXCEEDS 4.3v (OBDI) or 4.1v (OBDII). When the TPS output exceeds 4.3v, the Greddy BCC holds tight at a MAXIMUM 4.3v (when adjusted properly).

 

DO you want a cheap BCC that never goes out of adjustment, is simple to hook up, and costs 59 cents?

 

Go buy a 4.3volt (4.1volt for OBDII) Zenier Diode from your local electronics and solder it into the wire from the turbo pressure sensor.

 

The banded end of the diode should be soldered into the turbo pressure sensor's output (pim) wire, with the other end of the diode is soldered into the ground wire.

 

This works EXACTLY like the BCC, without the adjustability. We don't want adjustability...we want it exactly at 4.3volts. Greddy makes the BCC adjustable so it fits many different cars! We're paying for a feature that WE don't really need.

 

NOTE: GREDDY BCC USERS. Open your unit and set it for the right voltage. Every BCC I've seen is set too low from the factory (3.5-3.7v). This is not optimum for a number of reasons.

 

 

__________________

94 Supra TT-BPU

[Guest Ash]

 

 

It should work provided the diode was big enough to sink the current output from the pressure sensor.

 

I'm not sure what effect this would have on the pressure sensor. There will be some kind of resistor in series with the output terminal that will act as a current limit. But what the current is and/or whether is is of a sufficient power rating to sink that current for the required duration I cannot say for sure.  

 

Yours,

J

[THOR Racing]

The principle will work. By clamping the voltage input in the same way.

 

This has been known for a v.long time.

This is a limit REMOVER! however, so good luck!

 

The accuracy of a zener diode is dependent of the operating current and temperature which creates unpredictability in the temperature coefficient and the zener voltage and hence the effect of the fuel cut removal.

 

So on it's own it might work but you really need to control the current drawn.

 

The user of course can fit whatever he likes.

 

Pete

Note: The VFCC is a fully adjustable (universal) device which also has selectable  overboost protection, which raises the fuel cut to a new limit for your cars safety. This is the key advantage to the VFCC over the other products.