[Gmecm] PE lean issues on a ?747 TBI

[Frank McCracken]

WOW!
Is it common to have such good BLM readings??


----- Original Message -----
From: "Per Lonnborg" <perlon at passagen.se>
To: <gmecm at diy-efi.org>
Sent: Wednesday, July 06, 2005 8:40 AM
Subject: [Gmecm] PE lean issues on a ?747 TBI


> Hi,
>
> I run a Monza with a stock 350TBI with the 747 ECM from a ?88 Van, the
only
> modifications so far is headers into a 3" single free-flowing exhaust.
> I haven?t made any bigger mods in the chip more than lower the Main fuel
> Tables a bit because nearly all BLM values where on the rich side.
>
> I have made 2 trips to the strip with this setup, the first time approx
one
> month ago I did a 14.64/95 run.
> Last Sunday best ET was slower, 14.98/94 despite the fact I had switched
> to a lower gear rear end and with POSI!
>
> Last Sunday the weather temperature was much higher(=lower density).
>
> I logged the runs with WinALDL,(I?ve attached parts of the data) and after
analyzing
> the values one can clearly see that the car goes lean on WOT, especially
> last Sunday.
>
>
> Now to the questions:
> ---------------------
>
> 1. How does a 747 ECM compensate for air density changes in PE mode? Or
maybe
> it can?t?
>
> 2. Is there a way to see when this ECM is in PE mode?
>
> 3. If you look in the attached file, you can see that the battery voltage
was
> about 0.5V lower the slower run, can that be an issue? But I guess the
fuel
> pressure regualator should take care of that part...
>
>
> Oh, I should also mention that the knock sensor is disconnected, the cable
to
> it broke, and now I can?t reach the knock sensor due to that the headers
> are to close!
> In other words, I guess I?m a bit on the dangerous side with this engine
> in PE!
>
> Any suggestions would be appreciated.
>
> thanks,
>
> /Per
> Stockholm, Sweden


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