SAFC 1 + FCD Wiring ??

[r3dstar]

My SAFC is installed, boost cut at 14 psi. I install my new HKS FCD but the 2 unit use the same wire. So I need the wiring diagram. I install it but now, my fuel cut ain't change and when i try to raise it, the motor become lean at 4000 rpm.

Need help !

Thanks a lot !

[drjonez]

yikes.

1. you should try to get the car tuned. depending on turbo, FCO should be past 14 psi.

2. the FCD is the reason you're running lean.

3. it should be wired this way: AFM->SAFC->FCD->ECU just realize the FCD is negating most of what you're doing w/the SAFC.

[marc3]

3. it should be wired this way: AFM->SAFC->FCD->ECU just realize the FCD is negating most of what you're doing w/the SAFC.

doc, are you talking about the ecu ground wire?
that it should be the 2 safc grounds(1cm apart) , then the fcd ground ?
cuz this is what me and redstar were discussing this weekend, if the fcd ground went before or after the 2 safc grounds!!

[drjonez]

doc, are you talking about the ecu ground wire?
that it should be the 2 safc grounds(1cm apart) , then the fcd ground ?
cuz this is what me and redstar were discussing this weekend, if the fcd ground went before or after the 2 safc grounds!!

what? where did i mention gnd wires? this thread is about a SAFC and FCD....both of which connect to the AFM input to the ECU....

as for your grounding issue, gnd the FCD to another gnd.

[r3dstar]

Before i install my FCD everything work really well with my SAFC (14 psi boost cut) So i bought the FCD to put it at 17 psi.

Now i got some problem. I need the wiring diagram :( Someone already see this setup somewhere ?

[drjonez]

3. it should be wired this way: AFM->SAFC->FCD->ECU just realize the FCD is negating most of what you're doing w/the SAFC.

:3d_frown:

[SlimLim]

Has anyone had any luck with the SAFC + FCD setup? Or it just wont work at all?

[drjonez]

where is the difficulty?

there are NO problems using the SAFC + FCD....it just doesn't make sense since the FCD is manipulating the SAFC's output, making tuning even more difficult.

[SlimLim]

Ok. I just did a search and found plenty of problems with the combination and no positive comments hence i asked

[flight doc89]

3. it should be wired this way: AFM->SAFC->FCD->ECU just realize the FCD is negating most of what you're doing w/the SAFC.
the FCD goes between AFM and ECU??? If the FDC just messes with the AFM signal, then all I can foresee is lean operation and engine death. Please correct me if I am wrong, but te way you describe it, the FCD just makes the engine think there is less air, and thus delays fuel cut, but thus leans engine out :shrug:

[drjonez]

the FCD goes between AFM and ECU??? If the FDC just messes with the AFM signal, then all I can foresee is lean operation and engine death. Please correct me if I am wrong, but te way you describe it, the FCD just makes the engine think there is less air, and thus delays fuel cut, but thus leans engine out :shrug:

now you begin to understand my disapproval of people's utilization of the FCD.

in reality, the FCD is just a random pulse dropper.....thus making it impossible for the ECU to actually know what's going on. sure it delays FCO, but @ what price?

[Erkenz]

^

I am running a 1jz with safc and fcd, my boost is set at 17psi. Stock injectors and turbo's. I'm still in the 13's a/f r. Why is everyone running lean?

[drjonez]

heh. 13s aren't lean?

[CRE]

I suppose it would depend on when his AFR is in the 13's.. but yeah, if it's at WOT, :nono: .

I never really could understand the use of these things (FCDs). They've always struck me as a disaster waiting to happen.


For those of you who still don't quite get what the FCD does, it's essentially a signal clamp. Your AFM and/or SAFC's signal reaches a certain point and the FCD thereafter keeps telling the ECU that the airflow hasn't increased past that point. Up until that point the ECU gets accurate info about the volume of air entering the engine, after that point the ECU thinks you've leveled off and the ECU doesn't increase the amount of fuel that's injected.(Doc, correct me if I'm wrong on this.)

[drjonez]

...For those of you who still don't quite get what the FCD does, it's essentially a signal clamp. Your AFM and/or SAFC's signal reaches a certain point and the FCD thereafter keeps telling the ECU that the airflow hasn't increased past that point. Up until that point the ECU gets accurate info about the volume of air entering the engine, after that point the ECU thinks you've leveled off and the ECU doesn't increase the amount of fuel that's injected.(Doc, correct me if I'm wrong on this.)

no, it's not.

the FCD is a random frequency dropper. i did analysis on one a while back....i'll have to post that up.

[FIL]

no, it's not.

the FCD is a random frequency dropper. i did analysis on one a while back....i'll have to post that up.

of course, there are different types of FCD's, some are voltage clamps...

regardless of which way it works, the essential function of an FCD is to limit the amount of boost that the ECU thinks that you're running...

unless you have 2 boost sensing devices, one tied to the boost cut and the other to the fuel maps (I can't think of a car thats set up like this off the top of my head), then running an FCD is almost always counter productive...

what you could do instead, is to simply take your s-afc and lean out all the settings exactly the same amount across the range... then drive the car gently for a few days.... toyota's ecu firmware is smart enough to see the lean condition in closed loop (below 4000rpm and at low throttle) and to extrapolate that to the rest of the fuel maps... (this is also the reason it's hard to tune a toyota properly with an s-afc, unless you leave the areas monitored by the ecu as normal, it will alter your new maps to compensate)

[drjonez]

of course, there are different types of FCD's, some are voltage clamps...

sure, but we're talking about the MKIII supra here....so who cares?


regardless of which way it works, the essential function of an FCD is to limit the amount of boost that the ECU thinks that you're running...

unless you have 2 boost sensing devices, one tied to the boost cut and the other to the fuel maps (I can't think of a car thats set up like this off the top of my head), then running an FCD is almost always counter productive...

yups. the emanage can certainly do what you're describing....


what you could do instead, is to simply take your s-afc and lean out all the settings exactly the same amount across the range... then drive the car gently for a few days.... toyota's ecu firmware is smart enough to see the lean condition in closed loop (below 4000rpm and at low throttle) and to extrapolate that to the rest of the fuel maps... (this is also the reason it's hard to tune a toyota properly with an s-afc, unless you leave the areas monitored by the ecu as normal, it will alter your new maps to compensate)

long term applied correction.....which will then correct itself again should you change anything. hence the need to satisfy Vf.