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How difficult to learn how to tune stand alone EFI?

makemeknowit

makemeknowit

Kwisatz Haderach
Joined
May 19, 2020
Member Number
72
Messages
278
Loc
Memphis, TN
Looking at an '85 Mustang GT today and it has a Holley Commander 950, '88 short with factory forged pistons, ARP fasteners, new rings and bearings, TFS stage 2 cam, aluminum heads, BBK longtubes. It comes with a laptop with the software. I've never fooled with tuning efi. Even when I had my '96 Cobra with a 150 shot(dry) it was never on a dyno or had a laptop hooked up. Just put the used kit on and commenced to flogging the hell out of it.

I think the 950 is rather primitive by today's standards, 8x8 tables I think.

How much voodoo is involved? It's tuned for it's current config but in the event I make changes I'd like to think I'm up to the task.
 
I want to fry up some yokes before I work on my yolks.

I know nothing of this. Fryburgers and Dulcich pulled a commander 950 off of whatever on Roadkill Garage, I think it was the Ford drug-runner truck with a 460.
 
makemeknowit said:
Looking at an '85 Mustang GT today and it has a Holley Commander 950, '88 short with factory forged pistons, ARP fasteners, new rings and bearings, TFS stage 2 cam, aluminum heads, BBK longtubes. It comes with a laptop with the software. I've never fooled with tuning efi. Even when I had my '96 Cobra with a 150 shot(dry) it was never on a dyno or had a laptop hooked up. Just put the used kit on and commenced to flogging the hell out of it.

I think the 950 is rather primitive by today's standards, 8x8 tables I think.

How much voodoo is involved? It's tuned for it's current config but in the event I make changes I'd like to think I'm up to the task.
Click to expand...

A quick google looks like it's a 4bbl tbi with speed density and o2 sensor feedback. As long as the PO has the o2 sensor and map hooked up and everything seems to run okay I wouldn't worry about it being a little primitive. MPFI is slightly better but a tbi setup on a motor with a carb intent manifold will work just fine. Looks like there's plenty of documentation out there for it as well, I wouldn't worry as long as the laptop works and the software is available.


Speed density requires a little more work to tune the open loop fueling tables than a MAF equipped system but it's not that bad. I've done many junkyard GM sourced systems which are all 8x8 which IMHO is plenty for a hobbiest to try and tune.

Is the ecu controlling spark timing and using a knock sensor or did the PO ham fist it with a mechanical/vacuum advance distributor?
 
makemeknowit said:
Wideband yes, TFI distributor, no knock sensor
Click to expand...

It appears that the system supports a knock sensor and ignition timing control which is one of the big advantages of electronic engine control so I'd ask why he didn't hook that up. I think you would use a gm 7-pin EST module to control a duraspark distributor.
 
Dyno makes is easier but you can do it with data logging. Fire up the data logger, drive it a bunch, read the results, make changes and repeat. It's a PIA really that way though. I've done it on my painless kit and spend alot of time on it. Self tuning systems are completely worth it.
 
Ford of that vintage wouldn't have had a knock sensor, so trying to use what likely isn't there for ignition tuning will be tough. If you can get a compatible one, that would be a good idea. Lacking that, a best-guess ignition timing map and some dyno time would be your best bet. Mixture is easy with O2 and some driving time. You're "looking at", so are you maybe buying it from the last guy to tune it? Can you have him walk you through it?
 
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