through my searching i have yet to find a solid solution but.. heres what im dealing with. background of vehicle: 89 firebird formula with 305 tbi and automatic trans, bought from someone who purchased it for a parts car (only took hood) had a detached steering column when purchased, became clear previous owners where having vats issue of some sort (my hint being cut ignition wires and roughly removed ignition cylinder and extra vats modules) so i started by running my own 12g wire from aftermarket ignition switch to starter, car turned over but had no fuel or pump noise but started with starter fluid so had spark atleast, i then replaced the fuel pump and now has good fuel pressure and will starter for about 1 second (2 if i press accelerator) and immediately dies, injectors appear to spray well but only for that first second. when the engine dies injectors cut out, which i believe is normal when oil pressure drops. on start it reads 30 psi for oil. in reading it appears the vats may still be causing the injectors to cut out, is there any way of rewiring around that particular function of vats and get the signal directly to ecu or injectors? i imagine there has to be a solution outside of a bypass module or reprogramming/ replacing ecu..

 

Try removing the prom in the ecm. If it fires up it’s vats.
two ways to bypass the passkey a new vats delete prom or hz modulator from baker electronics.

 

VATS operates a relay, or allows it to operate, when it's happy. Someone with a wiring diagram of such a car could post it and it would help.

Seems it would be a simple matter to unplug the relay from its socket and plug a piece of wire into the socket in its place simulating the "happy" condition.

 

i will try that, now if it fires up without the prom, could i run without it, what functionality would i be missing with it removed?

 

If it’s fires up I would just run it long enough to move it if needed. It will run real rich in limp home mode.

 

to rephrase what im looking for solution wise, if the vats module itself is nothing more of a passkey or switch, can the injector control on the tb be controlled by direct signal from power to relay as i did with the line from the ignition switch to the starter? or is the vats module signal a somewhat coded signal that cant be so easily replicated?

 

The passkey module sends a hz signal to the ecm.
get a hz modulator or vats bypassed prom.
No other ways around it.

 

i will likely go with the bypass module. are they fairly universal or will i need to order a specific one based on my vehicle details?

 

Jumper the relay.

 

Yes jumper the enable relay. This has both frequency’s 30 and 50.

https://www.ebay.com/itm/GM-VATS-or-...EAAOSwXQpeq1fC

 

Hi brissdd , as Tuned Performance said , VATS actually does two different things , and both must be accommodated for . The first thing is , as Sofa mentioned , a relay which will not allow the starter to function , and the second thing is a square wave AC signal of either 30 or 50 HZ (cycles per second) applied to the ECM to enable the injectors . Jumping the relay is step one in eliminating VATS , and step two will have to be either the "HZ Modulator" to provide a substitute VATS signal to the ECM , or a prom with VATS deleted . If you just jump the relay you will have the starter operable from the key but no injector pulse from the ECM .

And now , since this info is all over the internet anyway , I'll tell you about the "VATS timeout" and let you in on a little (openly known) "secret" way to hear your car run without VATS being active . Turn your key on , and leave it on for a minimum of 5 minutes (waiting 6 minutes would be fine if your a patient sort , but it HAS to be at least a full 5 minutes minimum) . After 5 minutes has elapsed and WITHOUT touching the key , spray a bit of starting fluid into the TB and use your homemade starter jumper to crank the starter , the engine should start and run until you shut the key off .

For future readers of this thread ; VATS ONLY kills the starter and the fuel injectors , it does NOT kill either the distributor or the fuel pump , a car with bad VATS will still do the two second fuel pump prime and it will still spark the plugs (if the starter is jumped) , this is why with starter fluid and jumping the starter it'll start on the starting fluid and then quickly die as the starter fluid burns off since the injectors will still be offline ....

 

Hi orangebird , hope all is well

 

Thank You T.P. and likewise I hope your well also . I pray we all stay out of the virus' path , and sure hope it ends soon !

 

The right advice