Found this little beauty while replacing the normal filter box with a cone type.

I'd like to create a cold air box there, but am unsure of what that little puppy does.

 

i dunno, but its on mine too

 

It's the resistor for the low-impedance injectors fitted to 86-87.5 FC's. You need it so don't unplug it.

 

Ok, so moving it won't be a huge deal though. What a weird *** place for something like that though, you'd think they'd mount it on the firewall NEAR the injectors, hehe.

 

its a crazy place for a crazy engine!

 

Hahaha.....so true...

 

Moving it will be fine.

It gets very hot, so it needs to be in a place where it can dissipate that heat. On the firewall right next to the hot engine would make getting rid of that heat much harder.

 

it doesn't get all that hot and it really does not require cooling.

 

I wouldn't move it too far. It's there up away from the engine heat for good reason.

 

that made my day

 

So that box makes your low impedance injectors high, or the other way around? Im really not an electrical guy.. heh..

 

In basic terms it makes low impedance injectors look like high impedance ones to the ECU. 86-87.5 FC's have low impedance injectors and need a resistor, 87.5-91 FC's have high impedance injectors and don't need a resistor.

Yeah it does actually. It doesn't require direct cooling (like a fan), but it does need to be in a relatively cool place. It's a dropping resistor, used to drop the voltage sent to the injectors. The voltage absorbed by the resistor is disipated as heat. If you put it somewhere where it can do that easily (like it is) then it will work fine. If you put it somewhere hot (like right next to an engine) then it won't be able to disipate that heat as quickly, which means it will run hotter an eventually fail. This is basic electrical stuff.

 

So if you put high impedance injectors in the car, you would disconnect this or not, and how do you tell if an injector is high or low impedance?

 

The resistor is inline with the injectors' power supply and the injectors themselves, so you'd have to bypass it.

Put multimeter across an injector's terminals; if it's low impedance it'll measure ~3 ohms, if it's high impedance it'll measure ~13 ohms.

 

I dont seem to have that resister in that spot, but do have something similar to the photo bolted up to the front support the headlight bolts to, I thought this was the fuel pump relay or something. So if I dont have the injector resister that means I have to use High impedance injectors right?

Does it matter what ecu you have, such as N318 for example.

Cheers

 

The solenoid resistor is only used on 86 thru mid 87 cars.

It looks like the jpg I have attached. I show it intact and with the cover removed. It's composed of two resistors with the inscription ( 2X6ohms) on each of the two resistors.

One car of mine is a early 87 and I put high resistance injectors in it this year. I just cut the wires ON the solenoid resistor and spliced them all together then reconnected the plug to the harness. Put the resistors on the shelf for future use.

The fuel pump resistor/relay is located where you indicated. Early n/a cars do not have that item.

http://www.teamfc3s.org/forum/showth...threadid=33353

 

Better:

 

Well thanks for that, I went out to my car and it defenitely does not have those resistors, so I have to find s4 high impedance injectors, right.

Cheers

 

Okay, more stupid questions. I have just sorced a loom and ecu, the loom has had two resisters added into the ecu loom, the guy I brought it off said that he had two stock S4 injectors and then some 720cc secondaries which he thought was low impedance, this correct

 

It's a very common mod, since most aftermarket 720cc/min injectors are low impedance and need resistors.

 

Excellent, thanks for the info.

cheers