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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" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, 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 snyderman: It would bypass all the old engine electronics. P.S. I'm not changing the engine. So don't bother trying to take me in that direction Thx.

So, just wanted to address this... as I'm currently going through an Iron Duke rebuild with my daughter (we actually just finished it last weekend). Is your desire to keep a stock look, or you don't want to go through the hassle of changing out the motor? I ask because if you want to keep a Duke in there, there were several enhancements over the years.

Mid-1985 and up got a roller cam, which is quieter, and typically takes less wear.
1986 I THINK got a new intake and TBI unit.
1987 got an entirely new belt-drive system (serpentine), along with DIS ignition.
1988 got a new balance shaft which improves "smoothness of the engine," along with a different crank, pistons, and rods.

Each year saw a culmination of the previous year's improvements that went from 92bhp as a rackety "Iron Duke" tractor motor in 1984, to a much smoother running 98-100hp "Tech-4" in 1988.

So if you're OK with swapping out Duke motors, there's a lot of improvements you can get. I'm rebuilding my daughter's 1985 motor (which has a roller cam), and there are several improvements we're making, including replacing a LOT of the accessories (see this video here):




... bottom line (what you should take away from the video), every single one of the belt accessories has a more modern replacement that will literally "bolt in place."

Another thing you can also consider doing is replacing all of the pulleys with a 6-groove serpentine pulley, and you can literally have a serpentine belt system, using the alternator as the "tensioner" as you would similar to with a V-belt.

All of that said, my personal opinion, you could swap out the ECM with a new MicroSquirt system and eliminate a lot of the inherent drivability issues ... or so I've heard. I'll be doing this with my daughter on her car this summer.


EDIT: re-reading the thread, I understand all of what you want to accomplish. I agree somewhat with PMBrunell, though I'd recommend a MicroSquirt, specifically, this kit: https://www.diyautotune.com...foot-wiring-harness/

... I really like this kit, and I've purchased one myself. I got a lot of **** for recommending the FAST EZ-EFI 2.0 (which I intend to use for my V6), but I think you'll really like the MicroSquirt. It's exceptionally well laid out, well documented (literally... the back has the entire pinout), and lots of support. I get a lot of flack for this, but the factory ECMs are old. They were fantastic for the time, but they are slow (300 baud) and don't adapt well (or quickly) to changing environment. Hunting idle, 2000-rpm cold idle, etc... all these things could be fixed / eliminated with a newer ECM that makes a better (quicker response) to sensor changes. Of course, it's important to remember that most problems you have before an ECM change, will likely exist after an ECM change. Regardless, I think you'd see improvement by going with a modern ECM.

Note: swapping out the TBI unit won't fix your problem, it'll probably introduce more issues. BUT honestly, your Holley TBI unit is a definite improvement over the factory one, so I think that new TBI unit you posted is probably not worth it. But... all of these things will work better with a good ECM that can take advantage of it.


EDIT #2: (sorry) ... another thing I wanted to mention is, one of the really nice things about the Fiero, and when it was designed / made... is that the gauge cluster is totally independent of the engine management system. Like, there's almost nothing in the gauge cluster that makes use of the ECM. There's the shift light of course, but other than that, the gauges all get their readings directly from the sensors on the engine (some sensors are dedicated specifically to the gauges). So... point being, swapping out the ECM, while not "easy," does not require a complete rewiring of everything... just the wires that the ECM directly uses.

[This message has been edited by 82-T/A [At Work] (edited 04-24-2024).]