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EZ-Efi hot start problem

Discussion in 'FAST Support Forum' started by oruna1, Feb 11, 2014.

  1. oruna1

    oruna1 New Member

    Joined:
    Jul 2, 2013
    EZ-Efi immeadiate after hot start problem

    I installed a ez efi system on my 327 chevy (700r4 auto) July 2013. It works great but when starting the engine warm or hot as the idle drops after start up it drops too far and the engine stalls. If I feather the throttle for about 15 seconds it will allow me to take my foot off the gas and once again works perfect with no idle problems. At idle my IAC is set at 20 (600 rpm). I need the idle that low because it is a rock crawler with 12-230-2 comp cam (very mild) and with a 5:1 Atlas transfer case. It makes too much power to drive comfortably and wants to drive right through the brakes. The engine runs like a clock at that rpm but the hot start then stall because the throttle body overshoots the low rpm is kind of a pain. I have adjusted the rpm up to 750 but it still has the same result. I've been fighting this since the install. I've run from sea level to 12600 ft and it runs flawlessly. Cold start at 0 or 100 degrees no problem. Any suggestions for my hot startup?

    MSD 8360 distributor installed with tach signal off the dist gray wire
     
    Last edited by a moderator: Apr 3, 2014
  2. Msracing89

    Msracing89 Member

    Joined:
    Apr 19, 2011
    What are you running your Idle AFR at?
     
  3. oruna1

    oruna1 New Member

    Joined:
    Jul 2, 2013
    13.2 idle
    12.8 WOT
    14.1 Cruise

    Hot idle at 13.2 seem to be where the engine is happiest.
     
  4. Msracing89

    Msracing89 Member

    Joined:
    Apr 19, 2011
    I would not think that would be an issue at that AFR. Mine seems to be a little harder to cold start and always fires when hot. Then again I run a 550hp BB 440 at 11:1. So that is to be expected.

    I would make sure there is not a hot spot in the fuel line somewhere. It does not circulate fuel when hot until it fires up. At least mine does not.

    If the injectors don't prime when you turn the ignition on when hot, then maybe just barely touch the pedal before you engage the starter to get some fuel in the intake and see if that helps. I mean barely touch it!
     
  5. oruna1

    oruna1 New Member

    Joined:
    Jul 2, 2013
    It starts perfect when hot but as the rpm slowly drops down to idle it keeps dropping until it stalls. If by chance it doesn't stall it starts to surge up and down unless I catch the throttle. Cold start is no problem at all.
     
  6. gremlinmt

    gremlinmt Member

    Joined:
    Mar 13, 2013
    Consider turning up the idle screw just a touch, it'll lower it's IAC count a touch but might keep it running as it gets closer to the bottom. My idle used to surge hot on startup as well, I just kept dropping the idle target until it stopped, one tenth at a time. I'd drop it one, then go for another drive, then another hot start. The I think I'm at 12.8 right now. About 13.2 it would only surge on occasion but it didn't completely stop until 12.8 or 12.7
     
  7. oruna1

    oruna1 New Member

    Joined:
    Jul 2, 2013
    I can give that a try but I would think it will run rich at idle. I'll give it a whirl tomorrow if our northeast weather cooporates.
     
  8. schum

    schum Member

    Joined:
    Jun 3, 2011
    Timing can cause problems like this.
     
  9. oruna1

    oruna1 New Member

    Joined:
    Jul 2, 2013
    I don't understand what you mean about timing problems. I'm using a MSD 8360 with vac and mech advance, that's it. Cold start is just fine, and it runs well. Just the hot start as described. Can you explain what your thoughts are?
     
  10. schum

    schum Member

    Joined:
    Jun 3, 2011
    If you are using too light of a spring the advance comes in too fast at low rpm. If at 700 rpm you are getting 18 degrees, but it drops to 12 at 600. Just and example. I used one light spring and one medium spring.
     
  11. oruna1

    oruna1 New Member

    Joined:
    Jul 2, 2013
    I set my idle screw so it now has 16-18 counts at 650 rpm and also installed a msd box. I reset the timing to 16 degrees at idle (gives me 37 all in at around 1900 rpm ) and reconnected the vac advance. I hot started it a few times and it just catches itself before stalling but I really need to drive it so the system can learn the changes. I think I may be close now. I may get set the IAC for 10 at idle but I want to drive it a bit first. It may take a little time for some feedback since the weather is not great and our streets are full of snow and salt and I didn't want to drive it and get salt all over everything. If there are any other suggestions please let me know.
    Thanks.
     
    Last edited by a moderator: Feb 17, 2014
  12. Patrick

    Patrick New Member

    Joined:
    Feb 16, 2014
    Hi there
    Any feedback ? I have the exact same issue. I noticed that idle instability with hot engine is more pronounced with higher IATs. I don't need to feather the throttle that much.
    Maybe I should bump my idle AFR.
     
  13. Patrick

    Patrick New Member

    Joined:
    Feb 16, 2014
    Oh and I did a TPS relean procedure. It did improve things somewhat. But the idle hunting and random dying still occurs albeit less frequently.
     
  14. oruna1

    oruna1 New Member

    Joined:
    Jul 2, 2013
    Nothing yet. I stll haven't been able to get on the road. I have been getting my exercise shoveling snow instead. I don't have hot idle problems, again the only problem I have is right after a hot start as thd idle drops from the startup idle, the idle drops too low and really struggles to run unless it stalls altogether. If I catch it by applying the throttle the problem goes away and everything runs as normal. It idles very nicely at 650 rpm in neutral. Maybe I'll get to run it tomorrow. As soon as I get the right weather to run it (dry streets) I'll post the results.
     
  15. Patrick

    Patrick New Member

    Joined:
    Feb 16, 2014
    Great, thanks
     
  16. oruna1

    oruna1 New Member

    Joined:
    Jul 2, 2013
    Ok, I ran it on the road for around 5 miles and shut it down hot. On restart (about 3 minutes after shutdown ) it started right up as usual and as the rpms dropped it caught itself without stalling. I guess I'll have to see if it learns the msd box and improves but as of now it is an improvement since it isn't stalling. As I said in a previous post the IAC is at 16-18 at 650 rpm. If this after startup continues to improve I'll have it made. I spoke to tech (Gabriel) and he didn't think timing was a problem. He actually told me it would work great if the distributor was locked out and I set the timing for 36 degrees. I'll leave it at what I have just now which is 16 degrees (no advance) and the dist centrif advance at 21 degrees max (also have the 2 lightest springs) which nets out at 37 degrees total. I'll follow up in the next few weeks as the weather improves and I'll be able to drive it a little more.
     
  17. schum

    schum Member

    Joined:
    Jun 3, 2011
    Using the two lightest springs can cause an erratic idle. The timing jumps around at idle. Use one light and one medium.
    If you are using a MSD distributor use the black bushing and set the initial to 18 and that will give you 36 total
     
  18. oruna1

    oruna1 New Member

    Joined:
    Jul 2, 2013
    Update: I did change the advance springs to 1 light silver and 1 medium light blue. After starting hot the return to idle is much better and seems to be almost normal without stalling. I need to drive it more (now that the weather is finally better). Thanks for the timing advance spring idea. I wonder if I should start a new tune? Or just let the system build on what is already there.:)
     
  19. Webby

    Webby Member

    Joined:
    Sep 29, 2009
    Location:
    Southampton UK
    springs are for rate of timing advance. Dizzy needs stops to stop timing going below whatever your ideal idle timing is. Otherwise as the idle drops the timing reduces more which tends to drop the idle further and the IAC cannot cope. stops will also stop the hunting at idle as long as A/F is about right. Heavier spring/s will help smooth idle but may cause engine to be sluggish.
     
  20. oruna1

    oruna1 New Member

    Joined:
    Jul 2, 2013
    Using the 2 light silver springs the advance curve starts to ramp up at about 800 rpm where any other combo of springs on the MSD distributor the advance curve starts its ramp at about 1200-1300 rpm. So as the rpm drops off from the start up there is hardly any timing change (only about 1-2 degrees) with any heavier spring combo vs about an 8 degree change from 1200 to 600 rpm using the 2 light silver spring combo.

    Do you think I should start a new tune?
     

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