[Gmecm] 7747 High BLM at idle

Fri Aug 19 17:56:06 UTC 2005

> Your O2 sensor may cool down (rendering anything monitored relatively
> useless) and values start to go weird.
> 150 means it's starting to add fuel because 'seeing lean'.
>
> Is it really lean--how else will you know ?

Exactly.  I don't know whether to trust the O2 signal and I don't know if
I'm really lean or not.

> Are you still giving the ECM
> an
> 'in gear' signal ?

No.  I also have no VSS at this time.

> Is the idle speed higher than normal ?

No.  But there is no normal anyway, since it's been like this since I put
the EFI in place of the carb.  Idle is where I like it, although it surges
slightly when in park (maybe +/- 50 RPM).  It idles smoothly in drive.

> What about the
> spark curve ? Too much idle advance--exhaust temps will drop--O2's get
> colder -- however it's commanded to monitor the value still-- and BLM's
> get
> whacked.

I'm pretty sure the spark is calibrated correctly on the hardware side. 
The spark table is factory stock.

>
> I'd also tend to not rely on freeware so much. Just my .02
>

You mean winALDL?  What's the non-freeware alternative?

I have an "ostrich", if you know what that is, and Tunerpro RT, but I
haven't gotten around to trying them yet - even though it's been a year or
something since I bought the stuff.  Even so, I think you need something
like winALDL to go with Tunerpro at this point, since it doesn't display
the current operating conditions and ALDL data.  Things might have changed
recently though and I've been out of the loop.

Thanks.

> Lyndon
>
> ----- Original Message -----
> From: <charles at taildragger.info>
> To: <gmecm at diy-efi.org>
> Sent: Friday, August 19, 2005 9:06 AM
> Subject: Re: [Gmecm] 7747 High BLM at idle
>
>
>> Yeah, I'm able to see exactly which cell I'm in using the winALDL
>> program.
>>  When I'm in gear, it's in a different cell, and things seem normal.
>> When
>> I go to park, it switches to another cell and the BLMs in that cell go
>> way
>> up.  I'm not just looking at a BLM stream, I'm looking at a table of
>> recent or averaged BLM values as a function of VE table cell.
>>
>> I could just try to tune it out with the VE table, but I find it hard to
>> believe that the table is nearly perfect everyplace except one cell
>> which
>> is way, way off.  Has anyone on the list had such a thing; where the
>> factory table was almost perfect except for one or two cells?
>>
>> Thanks for the help.
>>
>> > You need to look at RPM and MAP both at idle in neutral and in gear.
> Your
>> > VE map is ok when you
>> > are in gear, but when you put it into neutral or park, the vacume goes
> up
>> > and the point on your ve map where
>> > it's idling in neutral or park is too high (The ve) reduce that part
>> of
>> > the
>> > map until your BL comes back down
>> > to 128.
>> > Mark
>> > ----- Original Message -----
>> > From: "Charles McDowell" <charles at taildragger.info>
>> > To: <gmecm at diy-efi.org>
>> > Sent: Thursday, August 18, 2005 7:49 PM
>> > Subject: [Gmecm] 7747 High BLM at idle
>> >
>> >
>> >> My truck has been running okay, but I finally decided to get around
>> to
>> >> gathering some more data to fine tune things.  I hooked up winALDL
>> and
>> >> drove
>> >> around for a while.  As I drive around, all the BLM table values in
>> >> winALDL
>> >> show 124-133 or so - not bad really.  The weird thing is that when I
>> >> pull
>> >> in
>> >> someplace, put it in park and idle it, the idle BLM cell (800/30 in
>> >> winALDL)
>> >> just climbs and climbs up to almost 150.  That same cell shows
> something
>> >> like 133 if I look at it before starting to idle.
>> >>
>> >> Any ideas what this could be, or where to even start looking?  It's a
>> >> 7747
>> >> for a SBC 350 with automatic, converted from carb.
>> >>
>> >> TIA
>> >>
>> >>
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>> >>
>> >
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