[Gmecm] $58 F29/F29E VE lookup weirdness

[Rob Handley]

My approach was to remove the 4000 RPM check limit code and the logic which 
uses the F29E table and F30 array, and add 6 more rows to F29, to take it 
from 4000 up to 6400. This makes it 15 x 9. I didn't spot a bug in the table 
look up code, but I only worked through it with one set of values - to make 
it easier. I found it tough going!

I'd be interested to know if the bug would affect my 15 x 9 table. I note 
that F1 is 14 x 17 and F2 is 15 x 5. Are these affected? I think, given that 
my engine is N/A and I'm only using a 1 BAR MAP sensor, 9 MAP columns is 
probably not so bad. I can't imagine where you found space for a 16 x 32 
table!

Thanks,

Rob

----- Original Message ----- 
From: "Dig" <turbodig at yahoo.com>
To: <gmecm at diy-efi.org>
Sent: 23 August 2007 21:47
Subject: Re: [Gmecm] $58 F29/F29E VE lookup weirdness


The problem there becomes the size of the table. There's a bug in the 3d 
table lookup that fouls up lookups over a certain size.

Our F29x is 16x32.

Dig

-----


BTW: If I've got it right, conversion of the code to a version of _F29_ that
goes up to 6400 is just a case of NOPing out some lines and using a hex
editor to set up the extended part of _F29_. If it ever stops raining, I
hope to test this out...

Thanks,

Rob

----- Original Message ----- 
From: "Dig" <turbodig at yahoo.com>
To: <gmecm at diy-efi.org>
Sent: 23 August 2007 17:22
Subject: Re: [Gmecm] $58 F29/F29E VE lookup weirdness


Sort of a well-known bug... The ALDL stream is reporting erroneous data.

It doesn't seem to be real; there is no corresponding fuel hit that I've
ever observed.

I haven't as yet found the cause, but I suspect it has to do with the timing
of the routine involved in sending data and the fuel routine.
It's on our "to do" list for code59.

----- Original Message ----
From: Rob Handley <Robin at FuryWorld.fsnet.co.uk>
To: gmecm at diy-efi.org
Sent: Wednesday, August 22, 2007 2:35:22 PM
Subject: Re: [Gmecm] $58 F29/F29E VE lookup weirdness

Tried it with a code modification to provide a hard-wired 'MAP' value to use
in the F29 look up, and the look up routine still regularly returned zero!

Robin

----- Original Message ----- 
From: "Rob Handley" <Robin at FuryWorld.fsnet.co.uk>
To: <gmecm at diy-efi.org>
Sent: 22 August 2007 09:03
Subject: [Gmecm] $58 F29/F29E VE lookup weirdness


> I've been looking at VE for the last few days and, after putting test
> values in F29, F29E, and F30 I spotted the VE regularly (every ~6 secs)
> reverting to the F30 only value. Looking back at one of last year's logs
> this was happening then too. It also happens with the ignition on and the
> engine not running !
>
> Has anybody seen this or have any suggestions why the table look up (as
> used for F29 and F29E) should be returning zero every now and then? I find
> the table look up code hard to follow.
>
> Robin