Fi Ecu Mods And Differences?

[Captain Obvious]

In case you want one other thing to check before you climb back under the car to take a closer look at the fuel pump... The AAR (you know what/where the AAR is?) is wired in parallel with the fuel pump. You can pop the connector off the AAR and probe the connections inside to see the same signal that the fuel pump should be seeing. Put a little noid light across those two terminals if you get energetic. Something you can see easy from the driver's seat.

 

So just like the fuel pump, the AAR should have 12 volts across it's two terminal connections:

 

- any time the key is in the START position, and/or

- any time the key is in the ON position and there is air flowing through the AFM.

 

So, if you've got power to the AAR at the correct times, you're looking for a bad fuel pump or connection to it. But if you're not getting the correct signals at the AAR either, then you've most likely got a problem with your FI relay.

 

Just thinking it's easier to check for that signal standing up at the front of the car instead of laying on your back under the rear of the car.

 

And, unfortunately, rossiz is correct that his trick with the oil pressure signal won't work for your year. That only works on 78's.

[wheee!]

Awesome guys! Thanks for the input!

[TomoHawk]

OK, so how do you "chip" the ECU?  The kiddies seem to think you can do that, and I  must be dumb if I don't know how to "chip the electronic fuel injection computer for more HPs"

[rossiz]

back when my car was built, getting "chipped" meant seeing ponch & john in the rear view mirror...

 

[Captain Obvious]

Haha! CHIPS!

 

I was thinking that the portion of the ECU case where the connector mates is an aluminum casting. I bet if you dropped it wrong, you could chip it.

[Captain Obvious]

I posted this in another thread where there seems to be fuel pump issues, but it's probably applicable here as well.

 

So are you familiar with the numbers on the FI combo relay? Here's the pin numbers related to the fuel pump and AAR:

- Pin 73 is power from the battery. Should be hot at all times.

- Pin 76 is the control signal from the ignition switch. Should go hot only in the START position.

- Pin 36 is the control signal from the AFM. Should be hot only when the AFM is passing air.

- Pin 74 is power output to the fuel pump. Should be hot in START and when the AFM is passing air.

 

The system works like this...

 

Power comes from the battery through the driver's side rear fusible link to pin 73. When either control signal (pin 76 or pin 36) goes hot, the relay connects pin 73 to pin 74 which then goes to the fuel pump. So when either in START or when the AFM is passing air, pins 73 and 74 are connected together and that sends power to the fuel pump.

 

So in your case, one or more of those four pins isn't working properly. Either because of a wiring or connection problem or a problem inside the relay itself.

[wheee!]

All very good info. I will be playing with this circuit this weekend for sure!

Sent from my iPizzle ringy dingy device....

[cygnusx1]

Chipping an early S30 EFI is as easy as.... I suggest these.

http://www.kettlebrand.com/our_products/potato_chips/#/our_products/potato_chips/?pid=61

[TomoHawk]

I thought you were going to refer to that 'SuperChips' website, that supposedly has "performance chips" for every car, all the way back to the Model-T?

 

BTW- my favourite is Zapps chips.

[wheee!]

[TomoHawk]

You forgot the +25% MPG

[wheee!]

Checked the AAR and the fuel relay. All is good there and the pump circuit is energized. Either the wiring harness or the pump is the issue at this point. I had to stop where I was as I had some company 'helping' me today... my grandson!

 

Say hello to Ryker!