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Idle Tuning Procedure

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  • Idle Tuning Procedure

    If you're having difficulty getting your engine to idle, give this a try.

    • Warm up to operating temp.
    • With Trans in neutral turn Idle control OFF.
    • Check idle speed, adjust the throttle blades to meet your desired idle.
    • Note the VAC value on the calibration module.
    • Go to fuel Modifiers and find the RPM and VAC setting closest to your current Idle and VAC readings.
    • Slowly add or subtract fuel until you get the best idle quality.
    • Readjust idle speed with blade adjustment screw to desired idle.
    • Again, note the VAC value on the calibration module.
    • Go to spark Modifiers and find the RPM and VAC setting closest to your current Idle and VAC readings.
    • Slowly add or subtract spark until you get the best idle quality.
    • Readjust idle speed with blade adjustment screw to desired idle, if necessary.
    • Turn Idle Control back on. There should be very little, if any, change to the idle speed with Idle Control either ON or OFF at Idle, in neutral.
    • Save changes to Position A in the calibration module.

    After that is done, drop the trans into gear. You should see a slight drop in idle speed and then the Idle control should bring it back to the desired speed.
    If you get any surging or erratic idle do the following;

    • Note the lowest RPM during the surging and the average VAC readings.
    • Return the trans to neutral.
    • Turn off Closed Loop Control.
    • Go into the Fuel modifiers and find the RPM and VAC settings closest to the values noted above.
    • Add 10% fuel.
    • Put trans back into gear and see if the surging has gotten better or worse.
    • If better, go back and add or subtract fuel until you get the highest VAC and a stable idle. Same goes if the surge is worse.
    • When you are satisfied with the results, turn closed loop back ON and save changes to position A again.

    Here are some things to keep in mind;
    • You must save your changes before turning the ignition ON/OFF. If they are not saved, they will be erased when you restart.
    • The ECU always starts in position A. you must save the changes to position A for them to do anything. You can save your current tune into B or C and restore them if you want. They will restore to A.
    • You should never have big jumps in the Fuel or Spark modifiers from one location to the next. If you have 10% in one location the surrounding locations should not very more than an additional 10%.
    • Only use the Idle fuel and spark settings once you have the regular Fuel and Spark Modifiers where the engine runs the best.
    • Closed loop control does not work at Idle.

    This is a big process, but it's not as hard as it seems.

  • #2
    If you have an engine that has a lot of idle vacuum, you may not be able to get it to idle lower than 900 to 1000 RPM. If you have this problem look at your spark advance value, if it is in the 30's you need to go into the spark modifiers, not idle spark, and take about 10 degrees or so out @ the 1000 RPM and 19" of Vacuum. This should bring the idle speed down.


    • #3
      idle tuning directions

      Dear Edelbrock
      I have been beating my head agaist the wall trying to get my engine idleing correct. The directions included with the unit aren't even close and I have been getting conflicting information from your staff. Where is this information? Where can I get the information on how to tune without guessing? Where is the information on how the system works? This is getting very frustrating.
      RPM Heads
      RPM cam


      • #4
        Will the same procedure work for the gen pro flo?
        I have no luck with the procedure in the installation manual.


        • #5
          Yes this will work for the original Pro Flo also.


          • #6
            Tuning Philosophy

            I have the 35070 kit installed on my GM 350 HO crate motor (all internal parts are stock for the crate motor from 2000 standards). I used the 3512 file as my base.

            I've been tuning for a few months now and am just discovering the usefulness of this forum. I have a question about trying to squeeze the optimum fuel economy out of this system (of course I want good power too, but I'm not drag racing this thing; it's a lifted jeep wrangler).

            I've been trying to tune to 14.7 afr across the board in my fuel modifier tables. It's slow going and I haven't seen any real world improvements. The engine actually runs well, but I haven't seen a fuel economy improvement (granted I've only put two tanks of fuel through it). Is there a trick with this combination of equipment? Are there different tuning criteria that I should use to get improved fuel economy?

            I'm also trying to lock down the idle where it needs to be, but I just saw your post on idle tuning the other day. I need time to try that procedure.



            • #7
              Thank you thank you...

              I wanted to take a minute to thank you for this informative post. Without it - never woulda got my rig fixed...

              I have reallly loved having the fuel injection on my 1969 blazer. Even with its problems, it was so much better than a carb.

              Slowly but surely I keep tweaking and getting my pro flo near perfect. I printed out the opening post of this thread and took it to the truck with me. I followed it step by step and I CANNOT BELIEVE THE DIFFERENCE in how my truck drives.
              It seems the biggest change came when advancing the idle timing. Mine was at zero all this time, having never messed with its setting from the previous owner.
              After driving twice tonight for extended cruise times I believe that this process fixed the following pain in the a$$ concerns.....

              Rough idle - not in a good way either. Now very smooth.

              Surge from take off - This truck was a bit rough around the edges when starting out.. way way smoother now, feel almost effortless to get the truck rolling.

              Back fire between shifts (after fire). - THis appears to be completely gone accept for WOT accel, which I think I will eventually get tuned out.

              After fire, during coast down on compression braking. - I hated the rolling crackle that it was doing. It sounded weird and horrible. Now it rumbles to a stop without so much as a gurgle.

              Idle surge on hot soak start. - THis was embarassing after stopping to fuel up or something... everyone checking out the truck then it would surge and load up..about die out, then snap up to idle.. over and over.. you would never guess it had injection on it at that time. NOT A SINGLE GLITCH ON START UP NOW.

              I have pretty loud pipes.. they just didn't sound good.. I know its crazy but the exhaust note sounds right now.. FANTASTIC !:

              THank you thank you thank you !!

              I am sure the real test is the drive to work tomorrow... stay tuned..


              • #8
                I have had an eratic idle since new and decided to tune as if I had a carb and dissy
                I took all spark timing below 900rpm and at all vacumn settings and made them all the same, as if a dissy connected to ported vac. It smoothed out immensely.