ok my question is..

i have a memcal for a v6 and a chip i had made so that the vats is removed. i just did a tpi swap from my 92 3.1 to a tpi speedensity system.i am gonna use the stock computer but put a v8 memcal in it. will i need to have the vats removed from the v8 memcal or is the vats stored in my computer?? also will the chip i had burned for my 3.1 work in my v8 memcal?? if so i can jus get a v8 memcal and use my chip i had burned for my 3.1.

 

VATS is set in the EPROM.

You'd need to disable VATS in the V8 bin before it'd work in your car.

Don't know why you'd want to put the 3.1 chip on the V8 memcal -- you'd need to reprogram it with a V8 bin anyway, so what's the point of shuffling chips around?

IMHO, the best thing for you to do would be to go is to get one of Craig Moates' memcal adapters with a ZIF socket, and an extra FLASH chip or two. If you go that route, you can leave the V8 memcal completely stock, burn a non-VATS V8 bin to the new chip, plug it in, and start tuning.

 

so i need a v8 memcal and a chip burned for it so that vats is disabled.is there any other way to do it without disabling the vats or chp burning?


thanks

 

Well, you could run a VATS system in the factory configuration.

Alternatively, you might do a search for "VATS eliminator" and see what you find. I think I've heard of a device out there, but I don't know the details. IMHO, it'd be a better investment in the long run to put the money towards chip burning equipment, though.

 

the only way the v8 memcal would know that there is a problim is because the difference in key resistance is that right??? all my vats stuff worked great when we originaly swapped the v6 harness for a v8. is there any chance that i could just hook it all back up and the key would work?

 

If the VATS stuff worked before, you should be in excellent shape.

The ECM doesn't know, or care what the key resistance is. There is a separate VATS module that reads the key. If the key has the correct resistance value, the VATS module sends a square wave signal to the ECM for fuel enable. In the chip, there is a bit that selects whether the ECM should look for the VATS signal, or not. If VATS is enabled, the ECM won't fire the injectors unless it sees that signal. If the VATS bit is disabled, the ECM will fire the injectors normally, regardless of the VATS signal.

The other half of VATS, is a starter enable relay, that's controlled by the VATS module. That part is independent from the ECM. You probably already bypassed that, so you just need to find a way to supply the VATS signal to the ECM. And if your old VATS module and lock cylinder still works, then you've got that covered.

Honestly, you really should get yourself a copy of the GM Factory Service Manual, which is published by Helms. Lots of good info there. Sometimes used ones can be found at reasonable prices. When you're to the point of swapping wiring harnesses and ECMs, you're way past where a Haynes or Chilton manual is enough to get by with. IMHO, anyway.

HTH,

 

long time since last post but still haveing troubles. the car has all original vats in it but still wont crank. finaly got done putting the tpi setup in and now no starter juice. if i bypass the pass key it will crank but wont spark or start...what gives?

 

does the vats in the ecm stop the car from sparking? and stop it from reading the key right if the ecms are out of a different vehicle?

 

Check the distributor wiring, it may be reversed. There are two opposite wirings to them.
Use a meter to check which terminal is the ground to have a reference.
If you put 12 volt pulse on the output lead from the distributor to the ecm, the fuel pump should run for two seconds. The wiring or just a bad module could be the spark issue.
The cranking, I would keep the module bypassed to get it to turn but you still need the ECM signal from the module to enable fuel.
If you can do a burn without the VATS and just get it running, then go back and see what the issue is with the VATS module itself. May have just died in the transition.
Vats should not in anyway be controlling the spark (per above, Starter relay and fuel cutoff, that all it does)
Recheck the ECM (again) to be sure you have all the grounds connected and everything is tight.
Hope this helps.

 

what do you mean by reversed.and 2 wirings? the harness is brand new from gm so i dont think anything is switched.

ok well here is the first prob none of them are ground when i tested them with a 12v test light.any ideas were that red/black one grounds?

i think im goin to try to solder in a resitor. i solder that in right at the bypass box correct?

thx :hail:

 

The reversed wiring was from the LT-1 vette distributor.
The four wire sequence is backwards compared to the "F" body wiring.
Just wanted to have you check that that wasn't part of your problem.

You should be able to put your test light clip end onto the positive from the battery (negative cable must also be connected to engine) Then probe the first and last pins on the four wire connector of the distibutor. One of them is a ground and should light your test lamp. That will give you the reference to compare against the drawing I put up here and be sure the wires were correct.

Yes, put the correct resistance right at the terminals on the VATS box.
The Vats box should then turn on your crank relay and output the signal to the ECM to enable fuel.

(just crawled out from mine, trans work is a PITA without a lift)
Gonna go take a shower.
Good luck, you should be on the home stretch now!