What exactly does the VATS system actually do on a VATS equipped car?
Does it not allow the starter to crank over?

My car doesn't have VATS.
I have a 91 ECM.
My car will turn over when turn the key.
I haven't tried starting it since I don't have everything wired up yet.

I just want to know.
Thanks.

 

Well, since your car is not a VATS car, there's no starter inhibit relay for the VATS to inhibit so it will crank and crank. It will not start though with the stock '91 computer since it is waiting for the valid VATS signal. Without that signal the computer will not fire the fuel injectors, no fuel no start....
You have a few choices, easiest is to get a chip programmed to disable VATS in the computer.

 

Thanks John,
I was just wondering if there was a Fuel and injector inhibit in the ECM or if it was just a starter disable.

I was going to pop in the SLP Prom and see if it ran without disabling the VATS, I guess I need to make some sort of adaptor to plug the SLP prom into the programmer to read the chip.

Do you have an adaptor you made? maybe post a pic or email me one so I can get an idea how to make one.

I want to leave the SLP prom intact and just read the info off of it.

Thanks,

 

A nice prom adaptor is in the DIY Prom Tech Article, check there.

As far as reading the SLP prom, if it doesn't work don't be surprised. Lots of those programmers change the code slightly so it can't be read or copied.

 

If it cant' be read or copied, how can I make it so that my ECM thinks there is a VATS module and it is getting the right signal?

 

It can be erased and re-programmed.

 

I don't want to erase it, just yet.
Is there something I can do to fool the ECM into thinking there is a VATS module installed in the car so I can run the SLP Prom and see how it performs?

 

Not that I know of. The VATS module puts out a coded signal so it's not as easy to trick the ECU.

 

Thanks John.
I really need to finish my car up, it's been tooooooo long since I last drove her.
I think it is warming up a bit so the garage will be a little easier to work in.
I've got like 3 wires to hook up and then I can start breaking in the cam and driving the car.

My 275/40/17 Kuhmo tires should be here tomorrow, I can't wait to see them on the car. Should look very aggressive.

 

An electronics friend and I tried to lie to the ECM since we were missing the vats box and it didnt work. Ended up getting a chip without vats to get around it.

 

Ya, I have the chip burning hardware and software so I am not fretting about it, I was just curious abou the VATS.

 

Zepher, the VATS can be tricked into thinking that a key is in the ingition at all times with a resistor. This is the way to do a remote start on a VATS equiped car. The problem that you have is trying to find out what resistor you need. If you had the key that matched computer that you have you could read the key. Since you probably don't have the key I dont know if this would be possible for you but I will try to find out tommorrow and get back to you.

 

I don't have a VATS module in my car or the VATS key reader either, my car is an 86 with a 91 ECM in it.

 

Without the vats module, the resistor will do exactly squat.

 

Ok, I really hesitate to respond to this but. . . I'm going to anyway. Waaaay back, (last year) I bought a Hypertech prom off eBay. The numbers were like 422 for a Camaro and 244 or something or another for a Corvette. Anyway, the Hypertech info on the web site was so small I didn't notice it had VATS. Knowing sort of how VATS worked, or wouldn't work for me, (resister key, starter interupt, fuel to injector shutdown, etc.) I wouldn't have bought it if I had known. I wired this third gen stuff in my '89 GMC pickup in '94 so I had an idea how things worked but wanted a performance chip for my THEN otherwise basically stock L98 engine.

So. . . to make this story a lot shorter, I read everything I could find on VATS on the net and got basically the same answers you're getting; except! I found the VATS module sends a 30-50hz signal to the ECM to allow the injectors to fire. The starter relay can be easily bypassed and I didn't, and you don't have that anway, but the ECM couldn't be easily fooled without rigging some electronics. Anyway.... AND DON'T LAUGH. . . I took a wire from THEN pin B6 of my MAF ECM, NOW pin GF10 on my SD 730 ECM, both Dk Blue, and I bared the wire and rubbed it across a good ground as fast as I could! On about the third try, the truck started! After that I could drive it until I shut the truck off. A simple 555 timer circuit could do the same thing. You can read about them on the net too.

Then I bought a VATS module off eBay. . .
Then I installed and actually enjoyed the Hypertech chip. . .
Then I replaced the engine with a 383 TPI setup with more money than I care to think about stuck in it. . . 6K+
Bought a Pocket Programmer . .
Bought Tunercat. . .
Then I bought three spare 165 MEMCAL adapters, added a flash chip to one, started tuning.
Didn't need VATS module anymore.
Upgraded to a SD 730 ECM. . .
Disabled VATS in everything I've programmed for it since. . .
Took out the VATS module, (two nights ago) hoping I never need it.

But anyway, I DID get it to start without a VATS module by rubbing that wire across a ground VERY FAST but it wasn't reliable since when I didn't do it correct I had to wait a bit before I could try it again. Plus, it was hard to do correctly.

If you're really want to get it started, and can't get the VATS programmed out of it, I'll loan you the VATS module. It takes about 10 minutes to wire up, you just leave the resister key in the cylinder and tuck it away somewhere. It's really fairly simple.


E-Mail me if you're interested

 

Thanks for the really cool info.
I do have the programming stuff and I basically bought the SLP Memcal as a spare since it was only $38, but I do want to try and use that Prom as my base for programming and do a compare with a stock prom.

I'll think about your offer.