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Surging idle hot start EZ-EFI 1.0

Discussion in 'FAST Support Forum' started by gremlinmt, Oct 21, 2018.

  1. gremlinmt

    gremlinmt Member

    Joined:
    Mar 13, 2013
    So, I'm down to the last bit of annoyance with my EZ-EFI 1.0 system and I'm hoping for a silver bullet.

    Engine is a 366CU Mopar v8. Torker II Single Plane intake. 16 degrees BTDC at idle. 32 degrees all in about 3500rpm. Cam is basic stock 4bbl cam 268/276. Idle set at 800rpm. 13.5 afr at idle. 14.5 afr cruise, 12.7 afr wot.

    Everything is awesome, good cold start, good performance, good cruise, good fuel economy.

    The only problem is on a hot start. The idle surges and sometimes dies on a hot start. If I key on and wait long enough for the O2 sensor to heat up, no problem at all.

    Suggestions?
     
  2. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Supposedly, the settings changes allowed in the new color handheld cure this.
     
  3. gremlinmt

    gremlinmt Member

    Joined:
    Mar 13, 2013
    I've got the new handheld, what changes would help this?
     
  4. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    The enrichment settings. It sounds like your cold enrichment is fine. You would work with warm enrichment (cranking fuel) and make sure the accel enrichment is optimized.
     
  5. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Advanced options>enrichment fuel is what you are looking for. It's all about balancing the three settings.
     
  6. gremlinmt

    gremlinmt Member

    Joined:
    Mar 13, 2013
    OK, I'll try adding a little cranking fuel and see how it goes.
     
  7. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    It could take a little less cranking fuel for warm start improvement.
     
  8. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Once you have the cranking fuel set for best warm start, optimize the accel fuel by looking for any warm engine light throttle stumble and adjusting the accel fuel to eliminate the majority or all of it. Your idle A/F ratio sets calculated cold start tables. It all works out to a balance that works best for you throughout all engine temperature ranges.

    Note: a 12.6 WOT may work out better for you.
     
    Last edited: Oct 25, 2018
  9. gremlinmt

    gremlinmt Member

    Joined:
    Mar 13, 2013
    I've made quite a bit of progress.. Currently at +2 cranking and accel fuel is still zero. I've leaned my idle afr to 13.7 and cruise to 14.8. I'm looking for a little gas mileage and it's still doing well at idle. I've got a little stumble under light accel, I'm going to try +1 accel if the stumble is still there in two days. Cold starts have been amazing compared to last year. I had a dual plane on last winter and it just wouldn't idle cold if the outside temp was less than 25F. This year it doesn't get grumpy until 15F and it's put up with 5F without any coddling.
     
  10. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Sounds good. If you go as rich as WOT 12.5 or 12.6, you may be able to lean the idle A/F more. If the idle A/F is tending to be running a little rich when cold, the leaner idle A/F will likely make those very cold starts easier and smoother during warm-up.

    Edit: Just something to try.
     
    Last edited: Dec 8, 2018
  11. gremlinmt

    gremlinmt Member

    Joined:
    Mar 13, 2013
    I've gone as lean at 14.0 idle but it's too darn cold to play with the throttle blades and it really wanted more throttle blade at 14.0.
     
  12. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Do you have WOT at 12.6? If it needs more throttle for a stable warm idle, using a leaner F/A, IAC may be incorrect. Remember, WOT really doesn't affect mileage as it only comes into play at hard throttle. It will just help the combustion temp out some with a leaner F/A. 13.7 isn't bad, but you may be able to get as high as 13.9 at idle. Be sure to only adjust F/A 1 tenth at a time as it affects all the idle fuel maps. Once the fuel maps adjust, you then need to go back into the fuel enrichment settings Cranking fuel affects warm starts above 125 degrees F, Cold start affects starts under 125 degrees F. Playing with cold start should help guide you in better cold starts and idle F/A changes. Idle F/A changes more heavily influence cold starts as they affect RPM and fueling of a cold engine under 125 degrees F.

    Remember, all of the above changes and TPS create a balance in cold and warm starting and drivability. Better fuel mileage is just a happy addition to the better tune. You don't want any plugs looking like they have run over hot.
     
  13. gremlinmt

    gremlinmt Member

    Joined:
    Mar 13, 2013
    WOT is 12.7, I don't have much to complain about at WOT, no stumbling, etc. I'll put another tenth in it and see if I notice a change. IAC counts on a warm idle in park is 15-18. If I move to 14.0 AFR at idle, it jumps up to 25-30. That amount of IAC count tends to cause stalling at stop lights if it isn't fully warm. Idle count in gear, when fully warm tends to be 45-47. At 14.0 it's closer to 70.
     
  14. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    It seems you have a very slight mechanical vacuum or fueling problem somewhere. IAC should only be high during cold start. At warm idle out of gear, IAC should be staying close to the setting unless compensating momentarily for a stop, return from a quick press of the throttle, or from loading like an air conditioning compressor or alternator drag.

    Once you find this small issue, you'll be able to get better numbers. I would try as rich as a 12.5 WOT, but no richer with regular pump fuel. I would also set cruise A/F to stoich 14.7. Watch your plug insulators don't look blistered white. 12.5-12.6 WOT with a stoich cruise A/F should have the inner and outer plug ceramics looking slightly tinged darker than bright white (very little even buildup).

    Over lean at cruise will cause stumbling as the engine tries to adjust back to idle A/F.

    This should help you some, but the small vacuum or fueling issue will continue holding you back on final settings, until the issue is solved.

    I would check the fuel regulator, vacuum brake booster, and distributor vacuum canister first.
     
  15. gremlinmt

    gremlinmt Member

    Joined:
    Mar 13, 2013
    800rpm idle is very high for this torque converter. I'm only turning over 1500rpm at 35mph. That's the primary load on my IAC.
     
  16. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    ? Idle should be 750. You need to tune over the entire range. That is the only way to find optimum settings for all driving.
     
  17. gremlinmt

    gremlinmt Member

    Joined:
    Mar 13, 2013
    I was having a lot of problems keeping it idling when pulling up to stop lights with a 750 rpm idle. By working at 800 I've been able to keep it happier. The IAC starts responding sooner as a coast up to the light. Eventually I'd like to start dropping the idle speed. I've noticed that the longer I run the tune the less likely it is to have an idle dip when pulling up to a light. Realistically I can only train that cold (140F) idle area a couple of times per day and every time I change the idle AFR it needs another day to really learn it.

    As for vacuum leaks, anything is possible. I've done a very through vetting for vac and exhaust leaks:
    1. Replace brake booster, line, and check valve.
    2. Replaced PCV valve, line, and installed a catch can.
    3. Replaced line to fuel regulator.
    4. Replaced line to vacuum gauge on dash.
    5. Got annoyed and replaced every single inch of vacuum line and all fittings. Installed spring clamps on all small diameter lines and new hose clamps on all large diameter lines.
    6. Torker II manifold installed this spring, Mr Gasket O-Ring gaskets
    7. Used brake cleaner with TPS unplugged to check all fittings and gaskets checking for change in idle.

    Exhaust in brand new professionally installed 3" from the stock exhaust manifolds back. Inspected yesterday while doing oil and chassis lube, No soot on any joint. O2 sensor tight in bore Manifold gaskets inspected for any signs of soot.
     
  18. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    You've been busy, but did you did you do a leak down test on the fuel regulator's vacuum port itself? If there is any leak down there on the regulator, added fuel is being drawn into the intake.

    Make all your settings at 750 RPM.

    At 140 F., the ECU is no longer controlling cold idle or cold start. This is only done by the ECU below 125 F.
    140 F is only the temp where the ECU begins fuel mapping.
    It takes a stone cold engine to see if idle A/F is too rich or too lean at start. If the plugs are wet seconds after a stone cold start, the idle A/F is too rich. You move that one tenth at a time to find the correct setting.

    Fully warmed engine, with timing correct and idling, you set the A/F for highest steady idle using a vacuum gauge. If this is affecting a stone cold engine start too rich or lean, you work with the enrichment settings. If the +-8 enrichment settings aren't making a needed difference, you adjust the idle A/F + or - a tenth until the enrichment settings do work.

    A video of the handheld would be helpful - before start and then running. Pictures of the plug ceramics after a warm up drive would also be helpful. Idle A/F affects the tip half of the plug ceramic. Cruise A/F affects the inner half deep in the plug. There should also be a definite color change in the middle of the plugs ground strap.
     
  19. gremlinmt

    gremlinmt Member

    Joined:
    Mar 13, 2013
    This evening, I started the truck and then clamped the line a couple inches off the regulator. I observed fuel pressure slowly rising to the 42PSI static setpoint. I repeated the test, same results. I cut the line, removed the barb fitting, added teflon tape, and re-installed. No change in behavior. Grrr. I'm on hold with FAST to find out if I need to replace the regulator.
     
  20. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Well, that was one way of checking it. As long as the clampoed vacuum remained, the regulator pressure should have remained the same. From what you've said, the regulator diaphragm is leaking - and this will cause problems like you've seen. I've used air conditioning gauges to read vacuum with adapters - always worked great for me.
     

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