How does the "fuel enrichment relay" work? Does it just open the circut? Or is there a resistor in there? I assume a resistor cause an open IAT circut should throw a CEL. I just got a used JRSC for my 99 DX but it didn't come with the relay.
Could I use a radio shack relay and either solder a resistor in parallel, or even a 'pot' so it was variable? How lean would I be if I didn't even hook it up.

 

I've got one of the fuel enrichment relays. It came with my 00 Si kit. If they are the same, i'll let it go for cheep.

 

I know the idea behind the fuel enrichment but not sure what type of resistor they have attached to the relay.
I got one of the first kits along time ago that was new but boxed wrong, I drove
mine for almost 2 years without the fuel enrichment until Oscar Jackson saw my car at nopi and asked where I hid my relay and boost switch at, then I realized I was missing parts. Without it the transition from vacum to boost is a little lean, that was the only thing I experienced.

 

The enrichment relay uses a 15k ohm resistor and a pressure switch. When there is no boost, the relay passes use the real IAT resistance so that the ECU sees correct air temperature.

When boost is present, the pressure switch causes the relay to pull the IAT's resistance up to 15k (the sensor's max). This basically causes the ECU to see that the air temp is about 0 deg F. As a result, the ECU will dump in more fuel and in the case of OBD2 cars, it will also advance the timing.

Sonny

 

Ok thanks. Guess I had it backwards.

 

FYI, you will typically run very lean without the IAT relay unless you raise your static fuel pressure (on the FMU) a lot.

Sonny

 

K, and I assume that's the nut and screw on top, like my B&M fpr?

 

Yes. Make sure you have a fuel pressure gauge when you adjust it or you will be totally stabbing in the dark.

Sonny