Fiero 3100 Swap

[JerryB]

I just completed a 2000 Malibu engine swap into a 85 Fiero, and used a 1999
Malibu computer and Trans. Engine is rebuilt with ported heads and lower and
upper manifold with hand built long tube headers. At start up the engine fired
easily but stalled after 3 or 4 seconds. Has been doing this ever since. Got
only a 452 code. Have nothing else but engine connected to the computer.
A friend thought it may have to do with a GM security system, is this possible?
If so how do I check and or get around this? Parts all came from a scrap yard
so I have no idea what options the original car had.

I`m an old school drag racer but new to computerized performance so any
help would be very appreciated.

[robertisaar]

code P452 is for fuel tank pressure sensor.

[IsaacHayes]

Eeek. That's the anti-theft system. Since it's a 1999 I'm not sure if that's old enough OBDII to not require all the body control modules and stuff or not. You'll need to have that programed out of the PCM though so it will run. Running on the original OBD1 system with a 7730 PCM swap would have been easier, but since you used the all electronic 4t45-e trans, you needed that newer PCM.

I'm not familiar with the newer security systems but I'm sure someone will chime in. You'll need the PCM to be programed to remove that stuff or get a module to trick it. I'm not sure what the newer ones look for as far as signal. I'm guessing the newer CAN stuff is even harder to crack than the older stuff where it took like a 5v 50hz signal or something to the PCM....

That code is just emissions crap, there is a pressure sensor in the fuel pump/tank area (on the original car) and it will give you a check engine light if your gas cap is not on tight because you are polluting with fumes coming out of the cap......... LOL... That would need to be programed out of the PCM too.

[robertisaar]

the PASSKEY signal is sent to the BCM which sends a signal to the PCM. not sure about the specifics of it, but i'm sure the info is out there...

[bszopi]

Did you replace the fuel pump when you did the swap? Not sure if the 85 Fiero came with MPFI or not, so the pump may not be able to provide the pressure needed to the rail.

[robertisaar]

all fiero V6 were L44, multi-port 2.8 iron head motors, so i'd say that's not the issue...

[bszopi]

Good enough. I don't know my Fiero history that well..

[95Grand-Am]

I don't know if it will work in your case but sometimes when you mess with the electronic in that era of GM's you can set off the security system. Then you have to leave the key in the on possition for @15 miniuts then try to start it. If that don't work let it sit anouther 15 min with the key on then try to start it. If that don't work you will probably have to have the security system disabled.

[Honest Don]

find somebody or a dyno shop with HPtuners? I know something can be done with ecotec and lsx stuff anyway...

[JerryB]

Thanks for quick response

I had heard about key on 10min off 10sec 10m on 10s off 10m on 10s off
then try to start, had not heard about key on 15min then try starting.
Will try both. Any ideas about anti theft cutting the spark or is it the fuel.
I have the PCM pinout but could find an input from the BCM, any ideas.
Also does anyone know were I can find a BCM pinout?
What might be the cost to have security system programmed out.

Jerry B.

[Honest Don]

I had heard about key on 10min off 10sec 10m on 10s off 10m on 10s off
then try to start, had not heard about key on 15min then try starting.
Will try both. Any ideas about anti theft cutting the spark or is it the fuel.
I have the PCM pinout but could find an input from the BCM, any ideas.
Also does anyone know were I can find a BCM pinout?
What might be the cost to have security system programmed out.

Jerry B.

Give your local dyno shop a call for an estimate. Since they wouldn't be doing any real tuning, it should be fairly inexpensive.

[robertisaar]

go to a dyno to have security features removed???

[Joseph Upson]

First identify what's missing to cause a no start or short run, fuel or spark. It could be something as simple as a crank sensor.