I have a VATS qusetion. MY 92 firebird has VATS. The preivous owner made it run by jumping the starter relay. Thats it. I went ahead and put the relay back in, and grounded the ground wire. But why does it start? The computer should cut fuel to the injectors untill it gets a signal from the VATS module. I have done anything, nor he, to that part of the system. I went so far as to cut the wire that goes from the VATS module to the computer, and it still starts. The only thing i can figure is someone changed the computer along the line. And if so, is there any way to tell? Its obvious is been out and unplugged.

 

jumping the relay will let the engine crank but like you said not start. Changing the computer (unless you're not swapping the mem-cal) won't do anything, but swapping in a new mem-cal will. Either it's got a new mem-cal/chip/prom (check broadcast code), or there's an appropriately sized resistor hooked to the Vats module and the relay wasn't working correctly to begine with.

 

The wires to the VATS module have just been cut. So unless its really hidden somewhere, therse no resistor that i can see. (oh, and the relay works, becuase with the relay hooked up right, no crank. So all i can see is someone changed something in the computer, but it dosent look that way, unless they changed the hole computer. Where is the broadcast code?

 

There are 2 firmware switches in the EPROM code:
1) VATS Select x=enable
2) VATS Diagnostics x=enable

VATS select enabled:
Will fire the enjectors only if it receives the correct frequency signal from the VATS module.

VATS select disabled:
Injectors fire without signal from VATS module.

My '88 is VATS select disabled because it has no starter relay.

 

Broadcast code is right on the mem-cal under the door on your ECM, usally 4 letters (ie: ANYX). I think you can cross reference it with the list here on TGO. But if your wires are cut then it's gotta have a non-stock or modified chip (mem-cal) in it (not necessarily a bad thing )

*edit* - scratch that cross referencing here, they've only got the TPI listed. Either way something has to have changed with it.

 

I can read "APFN" on the chip, but therse also 4 other letters/numbers that i cant read because a plastic thing is covering it. None of the wires where cut, but the connectors to the ECM had been removed at some point. I know most of you are thinking i should be gald, because it starts and all. BUt, not that its related, but i've been having a rough idle problem, so im checking all possible things. I have reason to believe some things have been changed, since the car has a tranny cooler and a 2500RPM stall converter, As well, the injector plugs have been replaced, but that may have just been maintance.

 

APFN should be all you need but I have no idea what is supposed to be in a '92 TBI. Almost sounds like somebody swapped a computer in from a similair-but-not-exact vehicle and never swapped mem-cals. Check with your local dealer and see if you can find out what is supposed to be in there.