Anyone have a picture of the 3800 PCM mounted behind the center console?

Is it possible, and how did you get it in there?

I got mine in there but the console would not position all the way back. I had about another half inch and could not get it in there. Did you cut something out/

I cut away most of the original ECM bracket, leaving just enough to screw the console to, and the bracket to the firewall.

Ignore the missing grommet, and cut hole, the owner did that before he gave up !

i dont have pics but mine was the same way, so im rewiring it next month, moving it outside with the s10 pcm tray, or maybe in the trunk. Unless a good idea pops up here may change my mind.

So that's the trick....cut away all the junk. Okay I try that...

Thanks the pic really helps.

https://www.fiero.nl/forum/A...090219-2-086464.html

Yeah, I saw the holder. I have no problem mounting the PCM, just finding a suitable place for it. I tried behind the seat, but that is so unprofessional. I planned to mount in under the center piece, but as I am finding it is a close fit.

It is a tight fit, on one I ended up sanding the fins down a bit at an angle just for the little extra room.

Sanding? No one mentione that. I am going to give it another try. I planned to get the car inspected in April, and so I wanted everything nice, and looking professional. Wires hanging out and stuff flopping around never looks good. Plus, it's a reflection on me, never mind if it runs well. LOL.

LOL, I only had to do it once, it just would not fit otherwise ! but it was just the "points" off the fins at the bottom of the PCM.

Just at the red lines

LOL... you used zippy ties and I still hang my head in shame if someone sees my harness. Nice clean install Mike. This will help me getting mine in place.

Steve

Remove the stock ECM holder and there will be more room...Mine sits behind the console but vertical....Nothing holds it in place as once it sat for some time it now stays on its own....

Mount from a 2000 S-10 with the mounting tabs cut off and screwed into the tinnermans that held the old tray.




Yes I had to cut out the back of the console and it seats all the way against the firewall.

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Project Genisis Lo Budget 3800SC swap in progress

88 formula 3.4L 4t60 swap

quote Originally posted by hercimer01:

I mount mine like this minus the plastic bracket. Instead, I get some good quality VELCRO and apply it to the PCM and to the firewall. The velcro will keep it from sliding around (the center console actually holds it securely against the firewall) and the velcro also keeps the PCM from grounding out on the sheet metal. Mounting it in this way requires NO modification to be made to the center console.

-ryan

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OVERKILL IS UNDERRATED

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

quote Originally posted by Darth Fiero: You do not want to allow the PCM case to ground to the chassis. Why? Because if the negative battery cable ever becomes loose from the block or breaks, the battery could try grounding to the block thru the chassis, PCM, and PCM harness which can damage these components if you are cranking the engine over.

Not sure that I understand this. If the negative battery cable comes loose, you lose all power in an instant.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, ZZP Intercooler, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: Not sure that I understand this. If the negative battery cable comes loose, you lose all power in an instant.

Battery connected, engine block or chassis ground become lose or disconnected; things that need a ground no longer have a path to ground except through the PCM (which can not handle high amp loads)... I think thats what Darth Fiero was saying

quote Originally posted by ALJR: Battery connected, engine block or chassis ground become lose or disconnected; things that need a ground no longer have a path to ground except through the PCM (which can not handle high amp loads)... I think thats what Darth Fiero was saying

makes sense to me.

Yea what I meant was if the large negative battery cable became loose from the block or the connection broke between it and the block, then the only way the battery will be grounding to the car will be thru the smaller wire coming from the battery terminal connection to the chassis (stock = battery tray). If the PCM is also grounded to the chassis, then the ground path will go from the chassis, thru the PCM, to the PCM ground wires going to the engine block (if you don't have any other ground straps hooked up). And if you attempt to crank the engine over, a high amp load can be sent thru this path and the PCM and/or wiring harness can be damanged. So make sure your PCM cannot make contact with chassis ground. Also make sure your PCM wiring harness grounds are not connected to the chassis. They must be connected to the engine block, cylinder head, or transmission case.

That's where mine is. I also cut out some of the back of the console but not the pocket itself so it's still functional. I used the 2.8 ECM tray so I could screw that to the firewall. Then I attached the 3800 PCM to the modified 2.8 tray.

Carefully pry the plastic plug from around the original harness. Run your wires. Pop the plastic plug back into the firewall around your wire harness. Once you have everything where you want it fill the plastic plug up with a pressurized can of black Permatex. Firewall sealed and wires protected from rubbing on the firewall.

[This message has been edited by 2002z28ssconv (edited 09-19-2011).]

I had mine in the consul but moved mine behind the seat, since the exhaust is on the other side of the firewall. The PCM was warm to the touch, and pretty heat soak. It is cool as can be now, and I dont see how it can be safely mounted back there. Did not someone say these things were mounted in the air intake for a reason? To keep them cool.

[This message has been edited by RotrexFiero (edited 09-19-2011).]

quote Originally posted by RotrexFiero: The PCM was warm to the touch, and pretty heat soak. It is cool as can be now, Did not someone say these things were mounted in the air intake for a reason? To keep them cool.

My 84 PCM caught on fire in the middle of a busy intersection on a hot day. I installed a computer cooling fan in it and that helped tremendously. (EDIT After replaced it of course). I am OK with cutting out the back of the console because it will help with cooling a little bit.I do plan on putting some sort of forced air cooling to it, I just haven't gotten that far yet.

[This message has been edited by hercimer01 (edited 09-20-2011).]

quote Originally posted by Mike Gonzalez: LOL, I only had to do it once, it just would not fit otherwise ! but it was just the "points" off the fins at the bottom of the PCM. Just at the red lines

I know its been a while and this would be pointless now; but in case others come across this thread...
If you flipped the PCM around so the fins are against the fire wall, you would not have to shave the fins as you did. With the fins back, the throttle/shift cables fit better and allow the PCM to be closer to the fire wall...

Also, are you guys removeing the sheetmetal to gain more room? Im fitting mine now and the only way I could get enough room was to cut out the sheetmetal...

If I could do it again, I would route the harnesses to the rear trunk. I would not put it behind the center consul. Just too hot. Bigger engine means more heat.

quote Originally posted by RotrexFiero: If I could do it again, I would route the harnesses to the rear trunk. I would not put it behind the center consul. Just too hot. Bigger engine means more heat.

Because the console gets too hot, or because you believe the ECM is running too hot?

Many stock 3800s have the PCM in a sealed box with no air flow at all under the hood.

If you put the PCM in the Fiero's rear trunk, it could get hotter there that it might in the stock Fiero center console location.

If you are concerned about your 3800 PCM running too hot in the stock Fiero ECM location, you can do what I did and mount a 12v CPU fan on one side of the Fiero's center console cooling grates to draw air in from behind one of the seats and blow it on the PCM. I've got my fan wired up so it turns on any time the key is on.

But, to be honest, I've never really had any PCM overheating issues when mounting the 3800 PCM in the stock Fiero ECM location. The Fiero's trunk seems to get a lot warmer since the muffler sits right up against it.

-ryan