Viceman

1st post on here but here is the cliff note version. I bought a 77 Corvette with a rebuilt LT-1 engine. I live in TN and flew down to TX to drive it back 2 days ago. I only got 30 miles down the road and the governor cap blew off and was dead in middle of nowhere. $225 tow to Chevrolet dealer Monday evening. Got a gov cap back on it and filled back up with trans fluid and now it want start. The computer is telling it not to. Chevy service dept is not getting a good reading of why but deff telling it not to start. 2 days in a hotel I'm getting ready to leave without it. Any suggestions before if hop a flight back home? I already regret this purchase and how I went about it so with that said any pos advice I could pass on to chevy people to make it start, I see how people can go postal! Lol (1st Lol in 2 days!) thanks in advance...

Learning_Curve

I have an LT1 in my '76. My only guess as to why the computer would tell the engine not to start would be the anti-theft. And even in that case, it would probably start and then immediately die. I had to have the computer custom tuned to eliminate that feature.

Now I can't think of anything that would be related to the transmission problems.

Wish I could help, but would need more information. Does the engine turn over? Attempt to start? Backfire? Any codes from the computer or sensors reading incorrectly?

Viceman

It turns over but no spark. They got a security code and a couple others but said it was reading computer correctly. They don't know the exacts of what's the original and the 96 stuff. And what kind parameters on the voltage and olms they are supposed to be getting?? That's strange to since it's been at a Chevrolet dealership for 2 1/2 days. I would think that' is things they could figure out. And of coarse the person I bought it from has been untraceable. No backfire at all either.

sunflower 1972

Unfortunately, new car dealership service departments are not equipped or very interested in working on "Custom Cars".

Learning_Curve

And with turnover at the dealership, not many have worked on 20 year old engine management systems.

carriljc

That should be OBD-2 readable. I'm surprised they cannot help you.
sounds like the anti-theft (VATS) except it should NOT just fail like that if it was already running.
Do you have any fuel pressure?
I used to read a friends 93 LT1 (not OBD-2) with my autoprom (and I'm no pro), so these GM Folks should be able to get info with all the cool toys they have access to.


Here is something to read and see if you get any hints.... hopefully not the opti-spark:
http://www.underhoodservice.com/diag...t1-v8-engines/

brent319

I don't know anything about the LT, but in my LS we had to turn off the VATS (anti theft) before we could start the engine in. If I remember correctly the car will turn over but won't fire. I did a quick google on 96 LT1 just now, and it sound like it also has a VATS. Could that be the problem?

cv67

more than likely it can happen at random
get rid of the vats
list your location there are still guys that work on these

sunflower 1972

I'm at work now, just checked my parts catalog and 1996 is INDEED a
VATS (we called it 'Vehicle Attempts To Start'). Hope you get it going.

lionelhutz

Maybe he used a VATS bypass module and it has failed. It's a fairly simple module that produces a 50Hz squarewave signal to the PCM.

http://www.ebay.com/itm/GM-VATS-or-P...-/281813159375

You can also use a resistor in place of the key and wire-up the original stand-alone VATS module to provide the same signal to the PCM.

The VATS uses the dark blue wire on pin A25 (red connector). Check it out and see if something is wired to it.

Of course, the ideal solution is to program the PCM and turn-off the VATS but who knows that the previous owner did or didn't do during the swap.

Very few of the GM techs at the dealers had a good understanding of that EFI system when the car was new and they actually worked on them all the time. In other words, there were few that could troubleshoot things outside of following the service flowcharts. The ones there today are clueless about it.

Can you get the codes?

Can you find out if there is an aftermarket or GM VATS module in the car?

Then, check what the codes are for and see if they point to something that is missing. For example, if you get an EGR code and the EGR is missing then that points to the original owner not re-programming the PCM which means the VATS is still active.

MelWff

did you try posting your question in the C4 forum since your issue is with a C4 engine and it's supporting components?

cv67

Google Henderson Performance in new braunfelds knows those cars real well. No dealership is gonna know about that car.

Corey will get you right

Viceman

I know this was about 6 months ago but I'm just reading it. I have been to the museum twice and had heard about this but never have had anyone walk us through the process like you did. I kinda felt like I was going through it with ya! One day I hope my stars line up and I can do something like that. The only word that is beating me in the face is "jeolous"! In a positive and motivateing way that is! 😏 And one more Congrats to add!!

Viceman

I did finally got some kind of reply from the seller, he sent this email...........
""Subject: VATS

this is a place to look, there is a small chip installed at one of the connectors at the ECM( sorry I could not get a picture for you) it should have a small LED on it and it should be on. it not, you mite check it's connection to the connector at the ECM .

go online and check GM VATS or PASSkey II Bypass Module For LS1 and LT1
VATS Bypass Module
Vats bypass module is intended for use when installing a GM engine equipped with the PASSkey I or II VATS (Vehicle Anti Theft System) into a vehicle missing the BCM (Body Control Module), or for remote start system. The VATS bypass module generates the ‘key ok’ signal normally sent from the BCM to the PCM (Powertrain Control Module) or ECM (Engine Control Module).
Feature:  Reverse voltage protection in the event of incorrect power connections  Waterproof  Low current consumption (5 mA)  Indicator LED to confirm operation  Light weigh  Small package (0.8” x 0.12” x 0.5”)  1 year warranty
VATS bypass module wires:  RED: 12V ignition of accessories  WHITE: Fuel Enable wire. 50hz or 30hz.  GREEN: Control wire. Connecting this wire to the Ground will produce Standard Vats Bypass signal (50hz) on the signal WHITE wire. If this wire is not connected to the ground the WHITE signal wire will produce older 30 Hz VATS signal used on some 90-93 PCMs  BLACK: Ground  BLUE: Optional led output. Connect external LED to monitor module activity. Flashing LED indicating working unit.  YELLOW: not used (might not be present on some units)
VATS bypass wire White (adjacent to Red wire) should be connected to VATS fuel enable wire (circuit number 229) usually a dark blue wire at the PCM, position varies depending on application: LT1, LS1 and TPI. Typically found on Pin 25 or 30 on the red connector or Pin 55 or 70 on the Blue connector, of found on B6 or D6.""

carriljc

So, did you get your car back to TN? Care to share what the problem was?

SH-60B

It was 3 days ago..........?

Viceman

Nope, the car is still in Seguin Texas at the Chevrolet place. This has turned into $4000 life lesson. The seller is going to take it back for $3500 less than I paid him for it. I literally had the car to myself for 30 min when all this went down. That offer was an insult, there were a couple diff ways I think he could have handled it, like just loose deposit, or help me fix it since he built it and told me car was good to go with no problems. But thats me and what I would have offered. Anyway the techs at Chevrolet said I should cut my losses and move on. They said the trans could be jacked up too but they needed to get it started to really check it out. This is my 3rd Corvette and I have purchased 4 cars in the past several years from online and long distance and they all went perfect. But like I said life lessons, just got my a## handed to me and get to give 4k for the privilege of said lesson.... :/

Viceman

The seller did send this email to me and to the dealership regarding "VATS"

""this is a place to look, there is a small chip installed at one of the connectors at the ECM( sorry I could not get a picture for you) it should have a small LED on it and it should be on. it not, you mite check it's connection to the connector at the ECM .

go online and check GM VATS or PASSkey II Bypass Module For LS1 and LT1

VATS Bypass Module
Vats bypass module is intended for use when installing a GM engine equipped with the PASSkey I or II VATS (Vehicle Anti Theft System) into a vehicle missing the BCM (Body Control Module), or for remote start system. The VATS bypass module generates the ‘key ok’ signal normally sent from the BCM to the PCM (Powertrain Control Module) or ECM (Engine Control Module).
Feature:  Reverse voltage protection in the event of incorrect power connections  Waterproof  Low current consumption (5 mA)  Indicator LED to confirm operation  Light weigh  Small package (0.8” x 0.12” x 0.5”)  1 year warranty
VATS bypass module wires:  RED: 12V ignition of accessories  WHITE: Fuel Enable wire. 50hz or 30hz.  GREEN: Control wire. Connecting this wire to the Ground will produce Standard Vats Bypass signal (50hz) on the signal WHITE wire. If this wire is not connected to the ground the WHITE signal wire will produce older 30 Hz VATS signal used on some 90-93 PCMs  BLACK: Ground  BLUE: Optional led output. Connect external LED to monitor module activity. Flashing LED indicating working unit.  YELLOW: not used (might not be present on some units)
VATS bypass wire White (adjacent to Red wire) should be connected to VATS fuel enable wire (circuit number 229) usually a dark blue wire at the PCM, position varies depending on application: LT1, LS1 and TPI. Typically found on Pin 25 or 30 on the red connector or Pin 55 or 70 on the Blue connector, of found on B6 or D6.""

carriljc

wow. that's a dirty deal. I thought it was quite gutsy of you to plan on driving from Texas to TN in an unknown car to begin with, but that seller didn't give you any breaks. bummer.

lionelhutz

A dirty deal?

You don't buy a 40 year old car and expect it to just work. You don't buy a customized transplant car without having a clue on how to troubleshoot it yourself. You also don't buy a 40 year old car and expect any kind of warranty let alone coverage of any and all expenses occurred or a buy back warranty unless it was all written as part of the purchase agreement.