How important is the RPM wire in a HKS FCD? needed or no?

[sportinct26]

Hi,

I purchased a HKS FCD from 1 of the member BUT it only has 4 wires(red,black,white and yellow) It DOES NOT have the green wire.

Is the green wire really neccesary or can i run this FCD on my mk3 without the green wire? have i Purchased the wrong FCD? (i hope not cause the member assured me its for mk3 supra.

please let me know asap as i will be installng this tomorow.

 

[Nick M]

I believe that needs to be hooked up in series with the airflow meter. But you really shouldn't use it at all.

 

[sportinct26]

I believe that needs to be hooked up in series with the airflow meter. But you really shouldn't use it at all.

thanks for the concern but its not neccesary. this will actually be my third set up.

but yeah back to the question. i know where to hook the rest of the wire i just dont wanna install it and then figure out that the rpm wire is cruisial.

if any1 know please chime in.

thanks

 

[MmmBoost]

as far as i know about the way that fuel cut is calculated, the rpm wire would be essential for the fcd to function.

fc is calc'd by airflow thru the afm at certain different rpms. each rpm has its limits. it isnt calculated by boost, so thats why i can hit 12psi and as the rpms go up it starts hitting cut.

the fcd would decide what afm frequency to "fake" to the ecu dependant on the rpms.

 

[mkIIIman089]

it isnt calculated by boost, so thats why i can hit 12psi and as the rpms go up it starts hitting cut.

Well, actually its just because the air flow is increasing as RPMs go up.

You have the wrong model FCD if it has no green wire. The only one that needs an RPM signal is the one used for the MKIII. (Type K3)

Sounds to me like you've been had.

 

[futeki_supra]

that blows