Can I just by-pass VATS and go?

[heavy85]

I'm VERY close to being able to start the LS1 up for the first time and am contemplating what to do with the PCM. If I just use a VATS by-pass box can I start it up and run without issue ... well other than the check engine light is always on? Will it run in some sort of derated protection or enrichment or something? I guess what I'm getting at is do I really have to have the PCM flashed to get rid of rear o2 sensors, air pump, etc if I'm willing to live with the check engine light? Eventually I will probably have it flashed out but am still trying to figure out the best way to go there and want to get it running over Christmas break.

 

Thanks

Cameron

[deja]

I'm VERY close to being able to start the LS1 up for the first time and am contemplating what to do with the PCM. If I just use a VATS by-pass box can I start it up and run without issue ... well other than the check engine light is always on? Will it run in some sort of derated protection or enrichment or something? I guess what I'm getting at is do I really have to have the PCM flashed to get rid of rear o2 sensors, air pump, etc if I'm willing to live with the check engine light? Eventually I will probably have it flashed out but am still trying to figure out the best way to go there and want to get it running over Christmas break.

 

Thanks

Cameron

 

In a word NO. I went through this on my lt1, this is my writup on the VATS.

Even though I don't have water in the engine or transmission fluid installed I thought I'd see if the starter would kick..............NO. When I had the PCM reprogrammed I left the VATS enabled and picked up one of those EBay bypass modules thinking that would eliminate the need for the GM key resistor. Well, I should have taken more time to fully understand how the VATS works. There are 4 inputs to the VATS, +12v always, +12v ignition switched in run and start, ground and 2 inputs from the resistor on the ignition key. There are 3 outputs, the security light, fuel pump enable and start relay enable. If you don't have the correct key nothing works! I was under the belief that the car would still start but the VATS would shut off the fuel after a few seconds. But that EBay bypass module does NOT take the place of the key resistor, it outputs the fuel pump enable so the PCM thinks there is a working VATS. Since I still want to use the VATS I measured the resistor in the Camaro key at xxx ohms with a spread of xxx - xxx, made a xxx ohm resistor combination to substitute for the key and installed it using a quick disconnect so I can remove it when I want to fully protect the car from theft.

Resistor list:

 

1 402 ohms (acceptable range 386-438)

2 523 ohms (acceptable range 502-564)

3 681 ohms (acceptable range 650-728)

4 887 ohms (acceptable range 850-942)

5 1130 ohms (acceptable range 1085-1195)

6 1470 ohms (acceptable range 1411-1549)

7 1870 ohms (acceptable range 1795-1965)

8 2370 ohms (acceptable range 2275-2485)

9 3010 ohms (acceptable range 2890-3150)

10 3740 ohms (acceptable range 3590-3910)

11 4750 ohms (acceptable range 4560-4960)

12 6040 ohms (acceptable range 5798-6302)

13 7500 ohms (acceptable range 7200-7820)

14 9530 ohms (acceptable range 9149-9931) 15 11800 ohms (acceptable range 11328-12292)

BTW if you still want that EBAY bypass module I'll sell you one cheap! I'm not using it.

[heavy85]

I'm not running the starting circuit through the PCM so I think the bypass module would work fine but I was also under the impression that module was all you needed for start/fuel/ect. What I'm worried about is some derate or ??? that the computer will enforce since the sensors are not plugged in. Depending on the answer to this question I may take you up on that module.

 

Thanks

Cameron

[deja]

I'm not running the starting circuit through the PCM so I think the bypass module would work fine but I was also under the impression that module was all you needed for start/fuel/ect. What I'm worried about is some derate or ??? that the computer will enforce since the sensors are not plugged in. Depending on the answer to this question I may take you up on that module.

 

Thanks

Cameron

 

I don't think so. But the fuel pump will be shut off after about 10 seconds. Thats what the Ebay bypass module is for, to create the fuel pump enable that nornally comes out of the VATS. The fuel pump enable powers the fuel pump relay. If you're not using the GM fuel pump relay either you should be good to go, except for that check engine light. I spent a whole night figuring out the VATS becuase I wanted to keep it in place for some theft protection.