[Gmecm] Hard Starting

[Jared Ryan]

I think my first guess - that it was clearing a flood - was correct.  I 
didn't realize that TBI had "clear-flood" programmed into it, but 
that's useful!

So perhaps I should increase the cranking AFR in the hot portion of the 
table by, say, 10% and try it and see what happens?

I think the idle is a bit rich across the board, but I haven't had time 
to run with WinALDL logging.  I will do that before making the change 
to the chip, to see what I have.

  ---> Jared Ryan <---
jryan at caminofx.org | http://www.caminofx.org

On Aug 15, 2006, at 4:22 PM, Rick McLeod wrote:

> My understanding on hot-start mashed pedal the ECM is in 'clear-flood' 
> mode where it disables injection in an attempt to clear a flooded 
> engine, therefore your assumption that it is adding fuel by opening 
> the throttle (if mashed) would be incorrect, it is actually cutting 
> fuel drastically. It may still be 'flooded' as evidenced by the black 
> poof, the routine is doing it's job. I would think reducing hot-start 
> fuel @ crank would be the first attempt, but the rest of the board may 
> chime in and challenge
>
>
> ----- Original Message ----
> From: Jared Ryan <jryan at caminofx.org>
> To: gmecm at diy-efi.org
> Sent: Tuesday, August 15, 2006 3:48:58 PM
> Subject: [Gmecm] Hard Starting
>
>
> I just need a starting point for this.  I need a good guess at which
> way to go to correct this problem.
>
> This engine "catches" *fast* on a cold start.  I just turn the key, and
> after a few revolutions it's running.  It smoothes out, and the ECM
> gradually reduces the idle speed.  No problem.
>
> On a hot start, it usually won't catch.  It cranks very fast, but just
> doesn't catch.  However, if I hold my foot down all the way on the
> accelerator pedal, it will always catch after several seconds of
> cranking.  It's just like if I was trying to clear a flooded engine and
> I open the throttle all the way on a carburetor.  When it does catch
> after doing this, there is a puff of black smoke from the tailpipes.
> Once it catches, it idles smoothly and there is no problem keeping it
> running.
>
> So... I have the programmer and TunerCat and WinALDL... what should I
> alter to make the hot starts easier?  Is there anything I can analyze
> with WinALDL that would tell us?  I call this a hot start problem, not
> an idle problem (again, once running, it's very stable and relatively
> smooth).
>
> My impression - based on having to open the throttle and that black
> smoke comes out when it catches - is that it's too rich on hot starts,
> but maybe it is too lean and I am adding fuel by opening the throttle.
> I don't really know how the ECM "thinks" at start-up.
>
> Any thoughts are appreciated!
>
> Engine: New GM long block 350, 9.2:1 compression, Crane 2032 camshaft,
> .214? int., .220? exh. @ .050" lift.
>
> Injection system: Rochester TBI, unmodified throttle body, 65 lb./hr.
> injectors, Edelbrock 3704 intake manifold, 14 psi fuel pressure
> measured before the filter.
>
> ECM: 1228746, ANLU .bin (1989 Chevrolet Caprice 9C1 Police calibration)
>
>   ---> Jared Ryan <---
> jryan at caminofx.org | http://www.caminofx.org
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