PCM.....Help!

[Unclebuck]

Hello,

I’m current building an off road car using a 3.4 motor out of a 95 firebird and in need of some help. The motor is from one wreck and the harness and PCM from another. Everything fit up perfect. The motor will start but not stay running for much more than a few turns. I have not been able to access the codes with my OBD2 code reader. It just comes up “fail”. I took the PCM in to be flashed and they were unable to do it, so the assumption was the unit was bad. I found another unit and had it flashed with no problems, plugged it in to the harness same exact thing. Start but no run and no codes. Any ideas??

Thanks

Bill

[FunkZ]

How's the fuel pressure? What are you using for a pump? Do you have the return line connected as well?

Double-check the firing order?

[98Camaro3.8]

Originally posted by Unclebuck:
I have not been able to access the codes with my OBD2 code reader. It just comes up “fail”.

3.4 won't work with an OBD2 scanner. It's an OBD2 connecter, but it's actually OBD1. Hence the term OBD 1.5.

[Camaro Dom]

uh... offroad? this is the first i've ever heard of an off road f-body. just my 2 cents tho. [img]tongue.gif[/img]

[ma4life]

He said it's an off-road vehicle and a motor from a firebird ... although I used to live in South Carolina and I saw a camaro on a truck chasis ... cough cough redneck cough cough

[StudlyCamaro]

is your VATS system hooked up?

[Unclebuck]

Thanks, everyone

Fuel pressure and return line are good, firing is right. I will hook up an OBD1 scanner. Any idea of what pins from the PCM I should connect to? What’s the VATS system? And yes it’s only the motor from the f-body. It’s a full tube frame car with long suspension travel (around 12” front and rear). It’s rear engine with a VW van transaxle. The body is a 73’ VW thing. I plan to run in southern California desert and Baja in place of my current VW powered buggy. Different yes…… but I really wouldn’t call it red neck

[ma4life]

Sorry, I wasn't calling you redneck ... it was the camaro on a truck chasis I cas referring to ... anyway, VATS is the chip in the ignition key that operates a security mode for our cars ... it basically puts a specified resistance in the ignition line that the computer recognizes and allows the engine to start ... a type of theft deterent. This is going to sound silly, but do you have the key from the car the motor came from ??

[Unclebuck]

Thanks,

That’s something I didn't know. I don't have the key I did see a wire on the schematic that went from the PCM to a thief deterrent module. I couldn’t find any more information on it in the manual that I have. I grounded the line but that obviously did not help. I will need to find a GM guy to some help on this one

Thanks again,

No apologies needed on the red neck thing, I do spend a lot of time in West Texas..I can take it.

[ma4life]

Buck,
This link may help you on the key issue ... http://shbox.com/1/4th_gen_tech2.html#pass_key ... I bypassed mine with their method and it worked like a champ ... I guess you best bet would be to get a resistor of each value and ry them all ... Good Luck

[John_D.]

On my '98 the BCM (body control module) sends a signal to the PCM, when it sees the right resistor on the key (VATS). The signal is not a simple on/off though, it is a frequency if I remember right.

However, on the '98, the only thing the pcm cuts is fuel if the VATS signal isn't there. So you can work around it. But then the pcm won't turn off the fuel pump if the engine dies.

Some of the tuning products will let you disable VATS.

[Unclebuck]

Thanks for all the help,

Got a vats bypass module from

Fuel Injection Specialties, 11051 Wye Drive, San Antonio, TX 78217
Phone: 210.654.0774, Fax: 210.654.1444
email: fuelinjection@fuelinjection.com

Three wire hookup,works great.

[ma4life]

So your motor is staying running now ??