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Need advise from the OGs



I've only bought one other car this cheap. A 1997 Firebird 3800. Put a fuel pump in it and a grocery list of other parts. Sold that bad boy $1700 cash
 
Itchy2500 said:
I don't know if you can run a 97 PCM in a 99 even with the harness.
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There's about a 13 wire difference to the pcm. But... I called Scott out on it and suggested using the 99 harness instead. It's very easy to mod a harness. Ask me how I know.

My 97 Bonneville had a 99 L36 harness that I modded for the firewall connector (would be relay center in a W body) to work. Ran a 99 pcm. At one point before I had a dhp I needed to have the correct vin, hence I made an adapter from 97 pcm to 99 wiring harness connector. It's a lot of wires to map, solder and hope you get right on the first try because you literally have one night to do it. FWIW I turned the key and it fired right up.
 


BillBoost37 said:
There's about a 13 wire difference to the pcm. But... I called Scott out on it and suggested using the 99 harness instead. It's very easy to mod a harness. Ask me how I know.

My 97 Bonneville had a 99 L36 harness that I modded for the firewall connector (would be relay center in a W body) to work. Ran a 99 pcm. At one point before I had a dhp I needed to have the correct vin, hence I made an adapter from 97 pcm to 99 wiring harness connector. It's a lot of wires to map, solder and hope you get right on the first try because you literally have one night to do it. FWIW I turned the key and it fired right up.
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Well Bill it turns out it's a 98. I know I'll still have to mod the 99 harness and will pm you when that day comes but since it's only a year difference could I use the 98 pcm?
 
I would drop the gtp engine into your car, make sure it runs and shifts good, sell the other tranny, and sell your orig engine. Part out the gtp that was t boned to the max, scrap. You may come our ahead.
 
freestyler659 said:
Well Bill it turns out it's a 98. I know I'll still have to mod the 99 harness and will pm you when that day comes but since it's only a year difference could I use the 98 pcm?
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if its a 98 pcm from the gtp, and your car is a 99 you could flash a 99 bin to it and make it work with some tuning changes like the tranny if you keep the na tranny.

what im saying is you have two good pcm's now 98 and 99 will swap bins with no issue.

a 97 pcm is its own animal and can only be used for a 97.

if you ever figure out what way you want to go, pm me, i can make all them changes in the pcm for ya. you just need to ship me one of the pcm's.
 


Mirraco said:
I would drop the gtp engine into your car, make sure it runs and shifts good, sell the other tranny, and sell your orig engine. Part out the gtp that was t boned to the max, scrap. You may come our ahead.
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The plan has changed but I'm dropping the 98 L67 motor and trans into my 99. Selling the L36 for 200 and parting out the t boned gtp. The plan is to come out ahead but new fluids and new gaskets are expensive.
 
WileyCoyote said:
if its a 98 pcm from the gtp, and your car is a 99 you could flash a 99 bin to it and make it work with some tuning changes like the tranny if you keep the na tranny.

what im saying is you have two good pcm's now 98 and 99 will swap bins with no issue.

a 97 pcm is its own animal and can only be used for a 97.

if you ever figure out what way you want to go, pm me, i can make all them changes in the pcm for ya. you just need to ship me one of the pcm's.
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Thanks Scotty! Yes I will send you a pm. As of now the gtp runs and shifts good so I'm going to swap both in at the same time.




I drove it home like this. That's a Pontiac for you
 
you can try to run it off the 98 pcm then. its just your vin# that wont match and that dont really matter unless you have inspection.

dont run it on the 99 pcm, the timing is way to high. and the trans wont be happy at all.
 


We don't have inspection here so I'm not too worried. I'm just trying to figure out how to make the performance shift button work and swap out the dic so I can have the crappy boost gauge until I hook up a real one. Bill let me know I'd have to modify the 99 harness for the map and bcs. First I have to get the motor/trans out to change gaskets. Plus I think the sc is leaking from the seal on the snout.
 
all you have to change i think is the map pig tail.

the perf shift button you have to add a wire to the pcm and run a button off it. or take the knob from the 98 and wire it up. take the pcm wire from the pcm plug in the t boned car.
 
Yeah the plan is to take the motor, trans, axles, pcm, dic, guages and shift knob out of the gtp. Plus whatever else I'm going to need. I'll probably list parts for sale on here too
 
freestyler659 said:
We don't have inspection here so I'm not too worried. I'm just trying to figure out how to make the performance shift button work and swap out the dic so I can have the crappy boost gauge until I hook up a real one. Bill let me know I'd have to modify the 99 harness for the map and bcs. First I have to get the motor/trans out to change gaskets. Plus I think the sc is leaking from the seal on the snout.
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freestyler659 said:
Yes bill I do have smog testing here.
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If they plug an OBD2 connector to read the car, then you want the vin to match. PCM would need to be updated.

WileyCoyote said:
all you have to change i think is the map pig tail.
the perf shift button you have to add a wire to the pcm and run a button off it. or take the knob from the 98 and wire it up. take the pcm wire from the pcm plug in the t boned car.
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And the BCS plug and now the wire for the perf shift. Anyone read what I write?

WileyCoyote said:
you can try to run it off the 98 pcm then. its just your vin# that wont match and that dont really matter unless you have inspection.
dont run it on the 99 pcm, the timing is way to high. and the trans wont be happy at all.
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It'll run off the 98. Can't pass a plugged in test though based on incorrect vin. Trans tables will be wrong, as will the fueling and timing and cylinder airmass and a bunch of other things.

It'll start on the 99.. but I wouldn't do anything beyond a test start on that pcm.
 
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