LT1-LT4 Modifications 1993-97 Gen II Small Block V8

VATS Worries in a 94

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Old Sep 9, 2010 | 11:26 PM
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Default VATS Worries in a 94

as most of you know im doing a v6 to v8 swap in my '94. it popped in my head today that i MIGHT have a problem with vats when i try to start the car once the motor is installed. BUT, the harness and ECU i got are from a '94 Z28. (motor is a 94 caprice) should i worry or no? seeing as how the z28 will have vats as well, i doubt it.
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Old Sep 10, 2010 | 01:25 AM
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I think I'd arrange to have a basic (read: mail order) tune done while it's all down, so that when you go to fire it up, VATS is a non-issue.
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Old Sep 10, 2010 | 06:42 AM
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The VATS module (which you are not changing) is going to read the key and then send the fuel enable signal to the PCM. It does not matter what PCM is in there. It's already a non-issue.
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Old Sep 10, 2010 | 08:49 AM
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so the ecu has nothing to do with vats? what about a buddy of mine who is putting a 96 buick lt1 in his 86 blazer? where is the vats module in my car?
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Old Sep 10, 2010 | 09:51 AM
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Throw a resistor inline
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Old Sep 10, 2010 | 10:16 AM
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Originally Posted by whytryz28
Throw a resistor inline
buhhh please elaborate.
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Old Sep 10, 2010 | 10:46 AM
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Originally Posted by tricked94camaro
so the ecu has nothing to do with vats? what about a buddy of mine who is putting a 96 buick lt1 in his 86 blazer? where is the vats module in my car?
I am also curious about this. I am putting a LT1 in my 300zx, i am using a 95 Engine/ECU, but i am using a stand alone LT1 harness, should i still worry.
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Old Sep 10, 2010 | 02:41 PM
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Originally Posted by tricked94camaro
so the ecu has nothing to do with vats? what about a buddy of mine who is putting a 96 buick lt1 in his 86 blazer? where is the vats module in my car?
The PCM receives a fuel enable signal from the VATS as already noted. VATS, itself is not in the PCM.

Your buddy will have to have the need for the fuel enable signal programmed out of the PCM. I don't know if the Blazer has any other security functions, but he might have to do some more work to enable starter activation.

The VATS module is under the RH side of the dash, attached to the HVAC housing.
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Old Sep 10, 2010 | 08:00 PM
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everyone should do away with the vats period it was a crappy way to stop people from stealing your car to start with. and unless you live in the ghetto no one is likely to steal your car anyways as all these cars are getting very old. if you have tons of money in your car do like me and put a good starter kill in.
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Old Sep 11, 2010 | 11:48 PM
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okay so i dont have to worry about it and my bussy with the blazer has to delete fuel enable/vats out of his pcm. or somehow enable it... he was talking about putting a bypass in it or a chip or something. sorry a bit tipsy right now
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Old Sep 12, 2010 | 01:35 AM
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Originally Posted by Enforcerws6
everyone should do away with the vats period it was a crappy way to stop people from stealing your car to start with. and unless you live in the ghetto no one is likely to steal your car anyways as all these cars are getting very old. if you have tons of money in your car do like me and put a good starter kill in.
Or a hidden fuel pump switch

But no stopping thieves if there desperate enough they can drag your car away or drag it on a trailer.
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Old Sep 12, 2010 | 01:44 AM
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Originally Posted by tricked94camaro
okay so i dont have to worry about it and my bussy with the blazer has to delete fuel enable/vats out of his pcm. or somehow enable it... he was talking about putting a bypass in it or a chip or something. sorry a bit tipsy right now

I dont know why but i have hard time understanding what you are saying.

Get a resister that's the same value as the chip in your key. then install it inline with the vat's system so that you dont need to worry about vats not working.

Bypass Vats
http://shbox.com/1/vats_bypass.jpg
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Old Sep 12, 2010 | 06:18 AM
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Originally Posted by tricked94camaro
buhhh please elaborate.
See below, I used this method on both my 01' and my 93'

Originally Posted by LT1
I dont know why but i have hard time understanding what you are saying.

Get a resister that's the same value as the chip in your key. then install it inline with the vat's system so that you dont need to worry about vats not working.

Bypass Vats
http://shbox.com/1/vats_bypass.jpg
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Old Sep 12, 2010 | 06:16 PM
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Originally Posted by LT1
I dont know why but i have hard time understanding what you are saying.

Get a resister that's the same value as the chip in your key. then install it inline with the vat's system so that you dont need to worry about vats not working.

Bypass Vats
http://shbox.com/1/vats_bypass.jpg
sorry. a bit tipsy last night. What i'm trying to find out is if my buddy needs to do anything to his PCM for his lt1 that he is putting in his 86 s10 blazer and by "doing anything" i mean delete vats from it. the motor and pcm are from a 96 roadmaster. will the motor start without deleting vats from it?
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Old Sep 16, 2010 | 01:13 PM
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Maybe someone that has swapped LT1 into a none Fbody will answer.

Ive read people delete it out of the PCM. I dont know if thats all it takes though.

Last edited by LT1; Sep 16, 2010 at 01:37 PM.
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Old Sep 16, 2010 | 03:25 PM
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Originally Posted by tricked94camaro
sorry. a bit tipsy last night. What i'm trying to find out is if my buddy needs to do anything to his PCM for his lt1 that he is putting in his 86 s10 blazer and by "doing anything" i mean delete vats from it. the motor and pcm are from a 96 roadmaster. will the motor start without deleting vats from it?
No. VATS will have to be deleted or a bypass module (not talking about the key pellet bypass) connected.

If the Blazer also has any form of VATS that keeps it from cranking (like the 4th gen does), that will have to be bypassed as well.

The 4th gen VATS has two parts:
crank (starter) inhibition
fuel delivery inhibition

Originally Posted by shbox.com

Components:

Pellet in the ignition key (one of 15 different resistance values)
Ignition key lock cylinder with sensing contacts allowing “reading” the resistance of the key pellet
Theft Deterrent Module (TDM) that monitors the system (this function is embedded in the BCM [Body Control Module] for 96-97 years). Modules are located under the RH side of the dashboard.
Theft Deterrent Relay (TDR) - relay that is wired in the path between the ignition switch and the starter.

Normal Operation
When you insert the key and turn to ON[RUN], the SECURITY lamp will light during the bulb check. The TDM reads the resistance of the key pellet and compares that to what is stored in its memory. If the reading matches, the SECURITY lamp should go out after 4 or 5 seconds.

The TDM (or BCM) sends a ground to the TDR to allow the starter to crank when you turn to the START position. Simultaneously, it sends a signal to the computer to allow fuel to the injectors. Your engine is allowed to start.
http://shbox.com/1/pass_key.html
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Old Sep 16, 2010 | 09:27 PM
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I'll be using the same original lock cylinder and key so i shouldnt have to worry, correct?

no TDM because the car motor and ecu is all a '94

Not sure what to do about a TDR in this situation.
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Old Sep 16, 2010 | 11:02 PM
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You seem to keep swapping back and forth question between your swap and your buddies swap. It's impossible to keep up. All the information you need is in the info and links I posted.
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