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  • Start and light throttle tuning

    Sorry, its long but all the info I can think of. Have multiple capture videos as well.

    Mopar LA 360 in 1st gen Ram 4WD, 727 auto
    Comp Cams XE256H-10 (212I/218E @.050 110 LSA)
    Vacuum @ idle appx 15 inHg @ 725 RPM
    Idle Ratio 13.7 (tried 13.5 to 14.5)
    Cruise ratio 14.3 (tried 13.9 to 14.7)
    Timing currently 17°, 32 max w/7 vac
    Have tried 5011 and 5013 tunes, 5013 runs better with much less Long trim after learned.

    Currently have all Cold Start and Crank fuel zeroed out but have tried up to 20% in both directions

    Problem(s) unsure if related or unrelated:
    On crank, get immediate fire then dies. Have used screen capture and does show slight lean immediately after fire but once stabilizes it shows rich. With 1-3% throttle can get it to start. Once started and running for a few seconds will idle decent. During warmup the A/F ratio trends about 0.4 rich from setting. Less issues on hot start but still occasional fire then dies. First 5-10 seconds after start engine does run.

    Self learning/short fuel trim seems confused at high vacuum/light throttle (coasting down or light accelleration). When using fast learn will pick up to almost undriveable within 10-20 miles of in town driving. When bringing slowly off idle will get very erratic -25 to +25 short term values. Holding steady 1-3% throttle engine will surge as A/F oscillates 11.5 to 16+. Gets worse the longer learn runs. Coas down is similar with generally large Short trim corrections.. At the same time, every other regime (steady cruise, high load, WOT) runs great with 0-3% short trim.

    I've reset learn multiple times, tried both maps as well as turning off learning and tried adjusting modifiers to get close prior to enabling. Also checked for Vac leaks with starting fluid while monitoring A/F ratio with none found. I did notice the vacuum compensated pressure regulator was dropping to appx 36 psi during high vacuum but disabled reference to a steady 43 psi with no change. Running out of ideas and looking for any recommendations.

  • #2
    Exhaust leaks?
    Try it with and with out PCV valve?
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    • #3
      Will be interested in seeing if you can figure out the cause. My 340 running map 5011 has developed the off idle stumble also with similar symptoms varying from extremely lean to rich until it levels out. This has developed lately and wasn’t always there. It starts fine warm and cold though. Have tried adding pump shot volume and time without any change. Increased fuel at cruise, reset map, slowed learning and nothing has eliminated or helped it yet.

      I have not changed anything on the engine so sort of at a loss as to where this is coming from. If I figure out something I will post here.
      Last edited by jm73340; 06-10-2020, 06:13 AM.

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      • #4
        No exhaust leaks I can find prior to or near the O2 sensor. Ill try the PCV, currently running stock type PCV.
        Does anyone have an idea when the system switches from crank fuel modifier to cold start. I don't remember there being a "cranking" sensor and it may help in troubleshooting.

        Also, for the tech support guys. If they could give an option to run the vacuum advance as a simulated "ported" vacuum" it would be helpful for tuning. Basically phasing the vacuum advance in with throttle like the stock system.

        Also, don't know if related or not but the problem with the off idle stumble seems to have gotten much worse after going to v65. But that could just be coincidental.
        Last edited by Tpalmerjr3; 06-10-2020, 09:31 AM.

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        • #5
          So, update...
          Tried removing PCV and plugging, no change. Still working through with some fuel modifiers in the idle range and went through the idle to 1200 tuning again. Going to keep putting miles on it but to got all the way to the point it would stall with VERY light throttle. Basically around 1% of throttle application Short FT goes from 1-3 to 15-20 then back low as throttle increases. If you hold in that transient the A/F ratio is all over the place, 11-16+ with Short Ft chasing it (-25 to +25). Really getting confused with the reaction here. Also, hooked up the timing light and base timing still solid at 12°. Did pull idle ratio down to 13.5 with vacuum right around 16.5.

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          • #6
            Wonder if the O2 sensor is ok.

            Tuning guide posted in one of the above "Stickys" gives all the information about "when", "what", and "how" about how the sensors interact with each others.....It's kind of dry reading.
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            • #7
              Yeah, I've looked through the guide. Nothing specific is listed for the crank to cold start transition. The only number I see referenced is in another section about the 12° timing lock and says 300 RPM will unlock it. Not sure on the O2 sensor. It seems to be reading fine except in low flow situations. Still looking into the PCV valve as well if an adjustable rate valve is necessary. I'm able to work some of the hesitation out with acceleration fuel but the self learn seems to be undoing the correction the more I drive. Doing some experimenting the engine idles much better during warmup with closed circuit off and just tuning cold start fuel to set A/F ratio. Do any of the Edelbrock tech support guys monitor this forum anymore?
              Last edited by Tpalmerjr3; 06-11-2020, 09:33 PM.

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              • #8
                Page 6:

                "Self Learn Min RPM and Closed Loop Min RPM
                The Self Learn Min and Closed Loop Min RPM values adjust the minimum RPM that these functions will operate. It is advised to leave these settings at 400 RPM (default). Adjustment to these parameters should not be necessary and are provided primarily for troubleshooting purposes. Contact an Edelbrock technical agent for further assistance."

                So it will learn at 400 RPM and above. But of course if you go into the app page ( Self-Learn Settings ) and click the ?. It tells you the the RPM's displayed Is the RPM when that function will be disabled.

                It can't adjust both ( ON RPM, and OFF RPM ) you only have 1 line of RPM's to adjust....0 to 8,000 RPM.

                Note: I'll try to go through all the documents this weekend ( with the ECU hooked up, just in case Demo mode is different to ECU connected mode ) and double check every thing.
                Crank Fuel has 2 settings:

                1st is "Crank Fuel".....As long as the motor is cranking ( till ? RPM )....This has to have a cut off time. Say you crank the motor for 10 seconds. I'm sure it's not going to be spraying fuel for 10 seconds......Also. I believe the TPS has to stay at 0. So if you have a funky throttle cable/rod that moves the TPS. Then it might stop spraying the crank fuel.....I believe it's actually a very high TPS percentage before it does this.

                2nd is the "Advanced" "Crank Fuel VS H20 Temp"......So the above is the Hot Motor Setting. This setting does 7 different temperature ranges. In case it's hard to start when not above 170F.
                Self learn does not work when accelerating.
                AFR target for accelerating works when TPS is more then 50%, or MAP displays -7.5".
                "Fuel Modifiers" page has indicators to let you know what stage your in.
                You did not post the setting for this.
                "Decel Fuel Cut" might be where your having some issues at.....It is not listed in the Tuning PDF.
                "Home", "Advanced Tuning", "Acceleration Fuel", Touch the ?, Then scroll down to it's definition.
                Some people have changed to 1100 RPM with good results.
                If you feel like the motor has been running rich. Then it would be best to replace the sparkplugs, after you have gotten it to run better....Carbon fouled plugs is the consequence of running a too rich EFI system.
                You didn't say what the IAC is set too.

                The Edelbrock moderators are here all the time. If you feel like you need some personal time with Edelbrock Tech Support, then call 1-800-416-8628.
                Last edited by BITE_ME; 06-12-2020, 02:33 AM.
                At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy

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                • #9
                  Thanks for the info
                  As far as moderators, just referencing that last time I was looking for some info, one of them was very quick to jump in with some direct and helpful info (Nate if I remember right.) I am getting to the point where I may need to get them on the phone directly. Was hoping I'd get cued into a easy problem that I had overlooked.
                  For the O2 sensor, any ideas how to tell if it is giving inaccurate info? It is giving data consistently and not showing any errors so I'm pretty reluctant to just throw parts at the problem without any info that says it's faulty.

                  Update to previous info: I've enriched the Idle A/F to 13.5 and brought timing to 16deg w/ 8 Vac and have now gotten closer to 17" Vacuum. Also ended up getting to a high load/low rpm range yesterday with light throttle (slow accel up hill from stop) that ended up stalling out the engine, re-fired quickly with no issue.

                  Self learn settings are still set at 400 RPM/Currently Fast.
                  Crank fuel I've been adjusting in order to get past these problems, currently -3, all temp ranges. But have adjusted to +/-20 incrementally in the process. Went back to 0 to eliminate compounded problems then slight change back to -3. Even waiting for O2 sensor to warm prior to cranking it's hard to get any definitive read while cranking. Fire is near immediate but then dies when I stop cranking unless I touch the gas (5-7% TPS). TPS stays solid at 0 during cranking so definitely nothing there.
                  -----------------------------
                  Fuel modifiers were zeroed out last time I reset the learn. Trying to eliminate some problems I turned of self learn and closed loop and used the idle modifier to take the A/F to about 0.2 rich, and ended at +10. Following I went through the suggested idle tuning to 1200 procedure twice.
                  I'm pretty sure I ended with +3 or 4 on the cruise leaving most of my cruise Long FT values at 0 +/-3 after learning for about 150 miles (mixed city)
                  ------------------------------
                  Decel Fuel Cut is at 1300. I had it lower previously but if revving in neutral it seemed like it was coming back late and not catching in time to level off at idle.
                  I was able to work out some of the flat spot with 10% Pump shot/2 sec but I think the self learn is washing that out now.
                  ------------------------------
                  I'll have to check plugs again, about 400 miles ago they were very clean. (Have about 2K miles on them from when I originally put this system in.)
                  ------------------------------
                  IAC is set to 10% (Idle/Neutral) resulting in around 25-35% (Drive) and 35-40% (Drive w/ A/C)currently. Have tried setting it as low as 5 and high as 15 with no real change.
                  ------------------------------
                  The truck had been running (and starting) much better through the winter but that was also on v63 of the software, not that that has anything to do with it just trying to identify all system changes. Ended up not driving it for a bit (6-7 weeks) during some other interior work I was doing. No other changes were made to the system.

                  Back to a previous comment, I've been looking to the PCV system, basically wondering if the stock PCV isn't adequate, but no real indication how I would know. I may try and get another PCV and experiment with adding some extra flow to it.

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                  • #10
                    isn't there an accelerator pump shot for throttle tip in ?

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                    • #11
                      You should try bumping up the idle timing from 16 to 18-22. EFI systems really like idle timing.


                      fleet man : "Home", "Advanced Tuning", "Acceleration Fuel"
                      At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy

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                      • #12
                        I'll try the timing move but currently getting close to there with the vacuum. 16 Base + 8 Vacuum giving a range that runs roughly 17-22 with idle control on. Really wish the Vac advance functioned more as timed advance that it does for ease of idle circuit tuning. One thing I've noticed since going to EFI is I haven't been able to run near as much total timing as before but it also included a cam/valve spring swap, nothing else on the bottom end or heads. I used to run 18, max 33, plus 15 vacuum on timed advance but anywhere near that and I get a pretty bad miss at highway speeds, appx 25-2700 RPM.

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                        • #13
                          I forgot to tell you. This system uses the timing to regulate Idle RPM.
                          At 43,861 MPH Elon Musk now owns the fastest car in this Galaxy

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                          • #14
                            Originally posted by Tpalmerjr3 View Post
                            I'll try the timing move but currently getting close to there with the vacuum. 16 Base + 8 Vacuum giving a range that runs roughly 17-22 with idle control on. Really wish the Vac advance functioned more as timed advance that it does for ease of idle circuit tuning. One thing I've noticed since going to EFI is I haven't been able to run near as much total timing as before but it also included a cam/valve spring swap, nothing else on the bottom end or heads. I used to run 18, max 33, plus 15 vacuum on timed advance but anywhere near that and I get a pretty bad miss at highway speeds, appx 25-2700 RPM.
                            As you’ve discovered you can’t run as much total timing as before EFI. 34* +- seems to be about the max. Your initial timing is most likely not going to effect the issue as I’m running 22* initial and have the same lean tip in. Pump shot increases and duration has NOT helped. Also moving initial timing and vacuum advance has not helped.
                            Last edited by jm73340; 06-12-2020, 01:12 PM.

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                            • #15
                              Yeah, found out about the timing modulation on idle a while ago. Makes traditional tuning/troubleshooting a lot more difficult. I kicked the timing up to 18° and picked up a new PCV just in case. Considering going to an M/E Wagner adjustable but due to the price ill probably experiment with modifying a few $3 ones to see if it helps first.

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