So today im going to put the inside of the car back together . And i got the 3800 ecu in the factory spot and iv trimed the ecu holder trey to make it sit in there . When i put the center arm rest console back on it almost fits very close . The bottom of the two fins on the ecu hit. Iv read that some peolpe just cut them abit or put a hole in the plastic arm rest behide the door. I really dont want to cut the console . Is triming the ecu fins ok?

I removed the factory ECM tray all together and would advise against cutting the 3800 PCM fins. What you can do is get 3M velcro adhesive strips and attach them to the PCM and the rear bulkhead if you'd like to keep them in place. There is enough room to fit the PCM without having to cut anything.

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Project L67 Fiero

I also removed the factory holder and made a bracket out of sheet metal to support the PCM then ran some long ty-wraps (vertically) around it to secure it.

GM put the cooling fins there for a reason.

quote Originally posted by Jfrost: I removed the factory ECM tray all together and would advise against cutting the 3800 PCM fins. What you can do is get 3M velcro adhesive strips and attach them to the PCM and the rear bulkhead if you'd like to keep them in place. There is enough room to fit the PCM without having to cut anything.

^^This is also what I do - fits fine and no cutting of the PCM's cooling fins is required to get it to fit.

Note that you do not want the case of the PCM grounding out against the chassis. The velcro straps can help prevent that. The reason why you don't want it grounding out against the chassis is in case your battery to engine block ground cable comes loose it could fry your PCM and PCM wiring harness if you have the PCM grounded to the chassis.

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OVERKILL IS UNDERRATED

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

Ryan, thank you for adding that to this thread. So important.

I still have to make sure I do all the grounds correctly. Can anyone link me to any diagrams showing needed grounds on a 3800 4spd swap?
Thanks

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===Always trying to find time to work on cars===
Louis Duet
Baldwin, Long Island, NY
"My mind spins like helicopter blades." -G. Rossdale
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"Blue" <= '85 Fiero GT
3800sc series 2 swap in progress
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"Boo" <= '81 Delorean DMC-12
VIN #5835
Stock PRV engine
Peugot 604 Intake manifold
Exhaust headers
Anti-3rd brake light

So i just put the ecu in . And since my car is an 84 my c500 is on the firewall. I moved it from pass side to the drivers side that way it does come close to engine in motor bay and theres more room or the drivers side of the engine bay for the swap harness to mate upto now instead of being all crammed in factory spot. So with doing that i put the swap harness in passener side hole now and took ecu trey out and used zip ties and cut some thin flat sheet plastic to put behide ecu from it grounding out . But now the factory c500 wiring runs across the top right side of the ecu to the left bottom near passenger side where it is from tge facotry . Now i have an other clearance problem with the arm rest not going down again it hits wire harness . Theres not engough room to pull it to the right side of ecu wnd then down.

Remove console insulation too even if new PCM fits w/ insulation on.
See my Cave, ECM Heat

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

I did remove the insulation .

The PCM on my 3800SC is located behind the driver seat on a tray on the firewall. I did trim the heat sink ears on the connector side about 1/2" maybe 2" in length for rear seat clearance. While I can't recommend this procedure and I wasn't sure that it was going to work, its been working for four years with zero problems. Subsequent swaps that I did have the PCM as Ryan mounts them, behind the console. That's a far better place to mount them but early on I didn't realize that there was enough room there.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, 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 "