Atomic EFI install

Discussion in 'High Tech for Old Iron' started by gs_jimmy, Feb 26, 2018.

  1. Ken Warner

    Ken Warner Stand-up Philosopher

    Few things to consider...

    1. Is the fuel pressure regulator connected to vacuum?
    2. If it's a "brown out" situation what happens if you pop on the high beams and put the AC/fan on high and soak up more current?
    3. I thought you were using the Atomic's PWM feature for fuel pump control?

    inquiring minds want to know... :)
  2. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    Yeah, I thought the system automatically compensated fuel pressure based on demand. There are a couple tests you can do, all of which watch AFR's.

    As mentioned, at idle turn on all electrical accessories you can, blower fan, headlights, brake lights, radio, and watch what the unit does with fuel pressure and pulsewidths. My assumption is it'll maintain constant AFR (+/- ~0.25), but if the fuel pressure drops and the pulsewidths go up, that would say you are running low on amps out of the alternator. If your AFR's lean out and the system does not compensate for it, then you are also likely running low on amps. If the fuel pressure doesn't change with all that turned on, then there is no problem.

    If you put a bigger alternator on, be sure to run a larger, or second, output wire from it to the relay controlling power to the fuel pump, to keep the alternator from overheating the old wiring system that is designed for 60 amps.
    300sbb_overkill likes this.
  3. gs_jimmy

    gs_jimmy Well-Known Member

    Got some time last night to work on the GS. Installed the new 105 amp alternator. rewired for internal regulator. Wiring is fine (previous post). Used same or larger gauge wire and had my son (electrician) there to check my work. I was able to put about 20 miles on it and noticed a couple things. I will need to drop the exhaust pipe on the pass side and fix an annoying leak. My guess is it is the O2 sensor port with a pin hole that the welder didn't quite get (yeah, I'm the "welder"). It is more pronounced under part throttle. Probley giving the computer fits too.

    Next is what feels like a misfire, again under acceleration. Going to tackle it after the pipe. I just replaced: Plugs, Cap, Rotor, coil, condenser (radio suppression). So could be a bad plug wire that isn't carrying the load. All the ignition parts are MSD or Borg Warner. I guess the computer seeing unmetered exhaust at the O2 could be that issue as well (air leak). Under cruise conditions (2200-2300 on the highway) it runs smooth. But when fuel is added to accelerate it seems like its breaking up.

    My AFR's are 12.6-14.0
    Computer is still "learning" the parameters but the idle seems to be a bit high. I set it to run at 670 RPM. Is running about 100 RPM higher. Cold Start also seems to be effected some.

    Other weird this is that the electric fan is not kicking in like it should. Wondering if I shorted it out some how. Going to "hard wire" to see if that is the case. I can always go back to the clutch fan set up. (Engine temps were 201 at cruise, but 214 when I got home. Engine has a 180* T-stat and the fan is set to kick on at 198*) I did kick on the heater fan to help bring down the temps.

    Last item is to finish up the new trunk seal. Not a tech thing, but needs to happen. I foresee some black fingers in my future (gotta love the 3M adhesive).

    I'll post again after fixing my weld job and taking it out to do another shake down run. If anyone has additional ideas let me know.

    BTW - Automotion Car Show is next week, May 19-20 at Wisconsin Dells, WI @ Noah's Ark Water Park
  4. gs_jimmy

    gs_jimmy Well-Known Member

    Think I found the issue.

    When I checked for a shorted fan, it came right back to life (hot wire to the battery). So, I pulled off the electric fan & related and reinstalled the mech fan. Fired it up misfire. Seems that my O'Reilly relay had shorted out on me. Once that and related wiring were removed, everything worked as before. Tonight I plan to put some miles on to confirm this.

    Also my AFR's are now much closer to the 14.7 I programmed into the system. 13.6 to 14.6. Also it is firing up without feathering the throttle. I moved the squirt feature from 25% to 27%. Now I'm onto cleaning and figuring out the pass side blinker. Also need to get some headlight adjusters. 20 years is long enough to live with weird pointed headlight beams.
    Harlockssx likes this.

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