[Gmecm] 7747 stumbling acceleration when cold

[Charles McDowell]

Let me ask my dumb question.  Why does the BPW need to be anything other
than "close enough"?  If it's off by, say, 10%, wouldn't the BLM pull it
in?

I just scaled off the spec flow rates, isn't that what a factory bin would
do anyway?

On Tue, Nov 30, 2010 at 1:11 PM, Aaron <aaron at creativeoverdrive.com> wrote:

> I've not seen "cop" injectors, but a quick search shows them to be 65
> lbs/h.
> But to calculate a correct BPW you MUST know what they flow.
> And the rated flow is based on a steady fuel pressure, so you'll need that
> as well.
>
> It's been so long since I've looked at the hack for the 7747, I can't
> remember what you should check next.
> I've always started with a bin that was close.
> Maybe Allen will pipe up soon. He's better at this than me.
>
> From: cmcdowell12 at gmail.com [mailto:cmcdowell12 at gmail.com] On Behalf Of
> Charles McDowell
> Sent: Tuesday, November 30, 2010 12:02 PM
> To: Aaron
> Cc: gmecm at diy-efi.org
> Subject: Re: [Gmecm] 7747 stumbling acceleration when cold
>
> I can check in the log file tonight for the items you asked about.  I was
> having major grief when I first installed this because I was given 305
> injectors by mistake.  I examined every tiny detail of the install so I'm
> pretty sure I don't have any air leaks.  Also bear in mind that it all
> works
> fine when warm.  I know things expand when they warm up, but it sure can't
> be anything major.  The thing idles and cruises fine when cold too.  It
> really seems like an acceleration thing.
>
> Does anyone know for sure what things need to be changed when using a
> larger
> injector size?  All I changed was the BPW to account for "cop car"
> injectors.  Are there other things too?
>
> Thanks.
> On Tue, Nov 30, 2010 at 9:19 AM, Aaron <aaron at creativeoverdrive.com>
> wrote:
> We have discussed the adapter plates before.
> They are notorious for creating a vacuum leak were the TB and IAC gasket go
> over one of the bolts.
> The IAC sometimes even hangs over the adapter plate, so there is no seal to
> the gasket.
>
> What is the IAC position at idle open loop and closed?
> Map voltage?
> TPS voltage?
> Fuel Pressure on the supply side?
> Fuel Pressure on the return side?
> Have you looked at the fuel spray pattern from the injectors?
>        I like using a dial back timing light to strobe the spray to see it
> more clearly.
>
> From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On
> Behalf
> Of Charles McDowell
> Sent: Monday, November 29, 2010 3:09 PM
> To: Eck, Joel
> Cc: gmecm at diy-efi.org
> Subject: Re: [Gmecm] 7747 stumbling acceleration when cold
> I'll double check my logs, but I think my temp is good.  Bear in mind that
> it's not like this thing ran well once and stopped.  It never worked well
> since I installed it.  I have an Edelbrock performer quadrajet carb
> manifold
> with an adapter for the TBI.  Thanks.
>
> _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org
> http://lists.diy-efi.org/mailman/listinfo/gmecm
>
>
> _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org
> http://lists.diy-efi.org/mailman/listinfo/gmecm
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.diy-efi.org/pipermail/gmecm/attachments/20101130/5adfce23/attachment.html