So my fiero has always had problems starting up until about a week ago when i decided to unplug this vats bypass module. Well it started and ran great for about another week, i started it and shut it off just because i could ha. I had to move a car without a batt, so i took the battery out of the fiero, when i put it back in the Fiero would not start. EVen before when it took about 10 turns of the key the car would eventually start but now... NOTHING.. well something.. i turn it over and it will rev up for half a second then shut off. It will do this all day long without starting. My fuel pressure is around 45 ish. I am getting spark, and there is power getting to the injectors.

I dont think the injectors are getting grounded because of that vats crap. Anyone have any ideas on how to get this taken care of? Why else would it not ground my injectors properly? i do not even get back fires, no fuel getting into the cylinders This sucks!

Here is the link to my CODES

https://www.fiero.nl/forum/Forum2/HTML/095812.html

when you removed the battery you cleared the code that allowed it to run without the vats signal. you will have to hook it up, start it, then disconnect it again while running. This will reset the code, and allow you to run. Or get the PCM reprogramed without vats.

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11.425 @115.60
Best 60' 1.543 seconds
3800 S/C 4T65E

On the 98-2007 3800SC PCMs the passkey can be deleted in the program with code modification. With the earlier computers there is probably a way to do this in the program as well. This would save you from using an external module. I believe that Darthfiero (Ryan) has done work on the early series I PCMs and can provide a definitive answer.

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

Im debating whether or not to just have Ryan reprogram it or not. Eventually i will put in the s3 3800 but i have to locate a tranny and thats proving to be a pita. To bad nobody wanted to buy this setup from me, it would be a shame to waste the wire harness and computer ... and axles.

quote Originally posted by Dennis LaGrua: On the 98-2007 3800SC PCMs the passkey can be deleted in the program with code modification. With the earlier computers there is probably a way to do this in the program as well. This would save you from using an external module. I believe that Darthfiero (Ryan) has done work on the early series I PCMs and can provide a definitive answer.

FWIW 1996 and 1997 PCMs can have the VATS disabled in the programming easily by just changing a switch parameter -- I have tested this myself and verified it works. However, 1998-up 4cyl and V6-car PCMs cannot have the VATS disabled IF it was enabled from the factory.

I have ran across quite a few 1998-01 Grand Prix GT and GTP PCM programs that had VATS disabled from the factory. I use one of these base calibrations for mail order PCMs people need reprogrammed for engine swaps so we don't need to worry about VATS.

All attempts to disable VATS in 98-up PCMs that have it such as the Regal, Lumina, 02-up Grand Prix, etc etc have been proven NOT TO WORK using HP Tuners, DHP Powertuner, and Tunercat software. I have tried this myself and their "vats disable" bits DO NOT WORK in calibrations that have VATS enabled from the factory. I can give you a long list of examples I have personally tried where it didn't work.

To make matters worse, the OBD-2 tuning software market is very tight lipped concerning disassemblies (hacks; or complete breakdown of the operating system and programming software used in these computers). So finding a useful commented disassembly that will help one locate the parameters in the programming that deals with VATS has been ellusive. And from what I have been able to find out, the newer computers don't have a simple parameter or flag that can be switched to disable VATS. What is required is a "patch" made to the operating system and/or calibration to force the PCM to bypass the VATS check, like what is available (and works) for the 05 Grand Prix LS4 platform.

-ryan

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5+ years on this same swap -- NO engine or transmission failures...

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

[This message has been edited by Darth Fiero (edited 11-14-2008).]

I'm running a 2003 GTP PCM and passkey has been completely disabled in the programming. Car starts fine everytime. The program was copied from a PCM that had the passkey disabled but the original program that was copied had to start somewhere. Maybe the answer lies within the capabilities of the GM Tech 2 ?

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Chris Hodson: i turn it over and it will rev up for half a second then shut off. It will do this all day long without starting.

Yep, thats VATS.

Why did you unplug the bypass? Oh, I see, cause you were having troubles starting it. Where did you get this module from? perhaps its faulty? I built one for mine, worked great, I forget where I found it, its the usual one everyone reccomends.

quote Originally posted by Darth Fiero: FWIW 1996 and 1997 PCMs can have the VATS disabled in the programming easily by just changing a switch parameter -- I have tested this myself and verified it works. However, 1998-up 4cyl and V6-car PCMs cannot have the VATS disabled IF it was enabled from the factory. I have ran across quite a few 1998-01 Grand Prix GT and GTP PCM programs that had VATS disabled from the factory. I use one of these base calibrations for mail order PCMs people need reprogrammed for engine swaps so we don't need to worry about VATS. All attempts to disable VATS in 98-up PCMs that have it such as the Regal, Lumina, 02-up Grand Prix, etc etc have been proven NOT TO WORK using HP Tuners, DHP Powertuner, and Tunercat software. I have tried this myself and their "vats disable" bits DO NOT WORK in calibrations that have VATS enabled from the factory. I can give you a long list of examples I have personally tried where it didn't work. To make matters worse, the OBD-2 tuning software market is very tight lipped concerning disassemblies (hacks; or complete breakdown of the operating system and programming software used in these computers). So finding a useful commented disassembly that will help one locate the parameters in the programming that deals with VATS has been ellusive. And from what I have been able to find out, the newer computers don't have a simple parameter or flag that can be switched to disable VATS. What is required is a "patch" made to the operating system and/or calibration to force the PCM to bypass the VATS check, like what is available (and works) for the 05 Grand Prix LS4 platform. -ryan

Ill try some different code if I get bored and see what i can come up with. I am curious if I can turn it on?

Check out this link. Some good info here from a PCM rebuilder
http://www.bsecorp.com/files/techtips/ST9303l.pdf

The info concerns itself with replacing a PCM that interfaces with an existing passkey, and goes through the relearn process but the article doesn't go into the steps required to shut the VATS off. It does indicate though what signals the PCM is looking for.
I also notice that there are about 4 or 5 DTC's for VATs but shutting these off may or may not disable the feature on the later computers. We know that the PCM looks for data from the passkey so the answer probably lies in the security interface codes . VATS has been disabled before but why HP hasn't made it simple is a mystery. I have a question up right now on the HP tuners forum.

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87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

1993 OBD-1 3800 PCM is correct.
First off, thank you guys for all the information so far. Last time i checked the TPS is brand spankin new and has a good sweep. Ill check the reference to the other sensors later today , my battery is on the charger right now.

I know that if i did not mess with the battery, my car would br running right now. ODD

Can i wire the s1 motor to run obd2?

are you trying to locate a 4T65E-HD??? I have one that's not going to be used now that I found a 5-speed car.

Can I?

quote Originally posted by Chris Hodson: Can i wire the s1 motor to run obd2?

You should. But you are going to be in for a lot of tuning of the spark and fuel tables which are much different from Series 1 vs. Series 2.