Haven't messed with FCs for a minute and could appreciate a refresher course. Picked up this S4 TII recently and trying to sort out what the previous owners did.

Main thing I'm trying to figure out is: did the previous owner run High Impedance 550cc RC Injectors on a Low Impedance harness?



I don't see an injector resistor pack...



RC Injector clips were spliced to the stock injector harness, but no resistors here either...



Car came with (4x) RC Inectors SL9-550 in both Primary and Secondary Rail. Stock N333 ECU and a Manual Boost controller.



RC Injectors Sl9-550 are "Saturated High Impedance" according to the RC website.


Again, thanks in advance for the help. Plan is to get this running again (or rebuild) and then rip it out and put into an S4 NA Vert.

Just trying to see what I'm working with.

 

If it happened to originally have the resistor box it could have been bypassed thus allowing high impedance injectors to be run which means there would be no resistors present.

 

I got an Rtek 1.7 with Low Impedance 720cc Secondaries coming. Lol, how do(/can) I make this work?

 

You would wire in the resistors on either wire at the injectors or you could wire them in at the ECU for the secondaries.

 

Cool, thanks.

 

also you should remove the FCD going to the pressure sensor. the 1.7 will not need this

 

the factory had two combinations.

the early 86-87.5 was a 4? ohm injector with a 8? ohm resistor so the ecu sees about 12ohms.

the late, 87.5-2012 was a 12ohm injector, so the ecu sees about 12 ohms.

if we look at ohms law, we see why.

12v/12ohms = 1 watt.

if we put low impedance injectors without the resistor it draws 12v/4ohms = 3 watts = blown ecu.

going the other way 12v/24 ohms = .5 watt, which is probably not enough to open the injector