[Diy_efi] Re: (was: IAC counts) VE tuning issues
Charles McDowell
charles at taildragger.info
Sun Jan 2 21:35:51 GMT 2005
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Let us know if you figure out the idle. I also have what seems to be
excessively high BLM right at idle. I have close to 128 all over but =
when I
stop I can watch the idle cell BLM just creep up to 140 or more. It =
seems
that the other cells within the same BLM grouping are fairly happy, but =
when
it goes all the way down to idle it gets messed up. I haven't had time =
to
mess with it for a while but I was guessing maybe the O2 sensor just =
cooled
off or something (I have headers). Or possibly it just needs more VE. =
I
have to work on it to see, but I'd be curious what you figure out.
=20
I know my 7747 can be set up to go to open loop at idle, but I don't =
have it
set up that way. Is this why they have it, because closed loop is =
flakey at
idle? I'm not sure how you'd tune your idle though without O2, unless =
just
by feel.
-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] =
On
Behalf Of Mike Frels
Sent: Sunday, January 02, 2005 3:08 PM
To: A list for Do-It-Yourself EFI
Subject: Re: [Diy_efi] Re: (was: IAC counts) VE tuning issues
AIR valve is working as it should. I checked the diverter valve with =
vacuum
on the manifold side and it doesn't bleed air into the exhaust. Before
warming up the engine I checked the exhaust manifold bolts and nuts. All
were tight, except for two. Guess which two? The two that hold the =
manifold
tight against the #7 exhaust port. They were completely loose. Oxygen =
was
coming into the exhaust just inches from the O2 sensor. Murphy's law =
again I
guess. After tightening I took it for a quick drive. The butt scan said =
it
was running much better. I took it for a quick second drive with proper =
scan
tool attached. Much better! Idle is still at 160 but all the surrounding
rpm/kPa ranges are yielding 130-145 BLMs.
I feel like I am now getting somewhere. Thanks for the exhaust leak =
tip...
Mike
At 05:50 PM 1/1/2005, you wrote:
I have had trouble with the AIR system bleeding air into the exhaust =
even
with the valve "off". Had to plug off the air line whlie tuning. Once I =
had
the idle set, and re-connected everything, it would creep to ritch. Had =
to
replace the valve in the end. Also had problems with the exhaust =
manifold
not sealing at the head on another vehicle and giving lean readings on =
the
o2 sensor. Idle blocks are hard to tune, in my opinion, since they have =
to
be lean to pass smog.
=20
--Karl=20
----- Original Message -----=20
From: Mike Frels <mailto:mfrels at ix.netcom.com> =20
To: A list for Do-It-Yourself <mailto:diy_efi at diy-efi.org> EFI=20
Sent: Saturday, January 01, 2005 5:42 AM
Subject: Re: [Diy_efi] Re: (was: IAC counts) VE tuning issues
I was reading HELMS this morning(couldn't keep the eyelids open past =
11:00
last night) AIR should only inject into the exhaust manifolds when cold =
and
in open loop to help burn converter destroying unburned fuel. When it =
warms
and goes closed the AIR should then divert to the converter. I interpret
this to mean the AIR system should have no influence on my 02 readings.
Just the same I am going to double check for proper operation today.
Hmmm...could I have switched the two connectors to the diverter valve =
last
time I reassembled after checking lifter preload?...I've done worse
before!...
I will report on progress as it happens. Yesterday's forecast for today =
was
50% chance of rain.
Happy New Year,
Mike
At 10:04 PM 12/31/2004, you wrote:
that may be the problem... while tuning, plug the AIR system as it =
injects
air to the exhaust like a giant leak...
=20
=20
-------Original Message-------
=20
From: Mike <mailto:mfrels at ix.netcom.com> Frels
Date: 12/31/04 21:54:09
To: A list for <mailto:diy_efi at diy-efi.org> Do-It-Yourself EFI
Subject: Re: [Diy_efi] Re: (was: IAC counts) VE tuning issues
=20
Don't you mean 'injectors are much SMALLER than #24 they are supposed to
be?'
=20
Anyway as far as oxygen getting into the exhaust stream the only thing I
have really checked is proper AIR system operation. That is working as =
it
should. I have not re-checked that exhaust manifold bolts since spring =
when
I put the engine in. Yes, I am still running cast iron manifolds. I will
take a wrench to the exhaust bolts and nuts tomorrow. Thanks for that
possible pointer.
=20
The injectors are brand new Accel 24 pounders. No, I did not have them
flowed before installing as I believed I could trust them from the =
factory.
Is experience counter to this?
=20
Mike
=20
At 05:59 PM 12/31/2004, you wrote:
>I look at it this way: BLM's greater than 128 means the ECM is having =
to
>add fuel to keep the mixture right. This means it's getting more air =
than
>it should according to the VE tables, which means the table values need =
to
>be raised by the appropriate factor. [(BLM/128)*current VE] is a very
>good formula for finding how much to adjust it.
>
>If you're getting 160 BLM's and you have 80's in the low-rpm VE table,
>then either your injectors are much bigger than the 24# that you think
>they are, or you have a pretty significant vacuum leak, or you're =
getting
>a false lean reading from the O2. First thing to do is check for =
exhaust
>leaks before/near the O2, as that will REALLY screw with your BLMs. =
Where
>did you get the injectors? Are they new or used, and have they been =
flow
>tested?
_____ =20
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<BODY>
<DIV><SPAN class=3D901542621-02012005><FONT face=3DArial color=3D#0000ff =
size=3D2>Let us=20
know if you figure out the idle. I also have what seems to be =
excessively=20
high BLM right at idle. I have close to 128 all over but when I =
stop I can=20
watch the idle cell BLM just creep up to 140 or more. It seems =
that the=20
other cells within the same BLM grouping are fairly happy, but when it =
goes all=20
the way down to idle it gets messed up. I haven't had time to mess =
with it=20
for a while but I was guessing maybe the O2 sensor just cooled off or =
something=20
(I have headers). Or possibly it just needs more VE. I have =
to work=20
on it to see, but I'd be curious what you figure =
out.</FONT></SPAN></DIV>
<DIV><SPAN class=3D901542621-02012005><FONT face=3DArial color=3D#0000ff =
size=3D2></FONT></SPAN> </DIV>
<DIV><SPAN class=3D901542621-02012005><FONT face=3DArial color=3D#0000ff =
size=3D2>I know=20
my 7747 can be set up to go to open loop at idle, but I don't have it =
set up=20
that way. Is this why they have it, because closed loop is flakey =
at=20
idle? I'm not sure how you'd tune your idle though without O2, =
unless just=20
by feel.</FONT></SPAN></DIV>
<BLOCKQUOTE dir=3Dltr style=3D"MARGIN-RIGHT: 0px">
<DIV></DIV>
<DIV class=3DOutlookMessageHeader lang=3Den-us dir=3Dltr =
align=3Dleft><FONT=20
face=3DTahoma size=3D2>-----Original Message-----<BR><B>From:</B>=20
diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] <B>On =
Behalf=20
Of </B>Mike Frels<BR><B>Sent:</B> Sunday, January 02, 2005 3:08=20
PM<BR><B>To:</B> A list for Do-It-Yourself EFI<BR><B>Subject:</B> Re:=20
[Diy_efi] Re: (was: IAC counts) VE tuning =
issues<BR><BR></FONT></DIV>AIR valve=20
is working as it should. I checked the diverter valve with vacuum on =
the=20
manifold side and it doesn't bleed air into the exhaust. Before =
warming up the=20
engine I checked the exhaust manifold bolts and nuts. All were tight, =
except=20
for two. Guess which two? The two that hold the manifold tight against =
the #7=20
exhaust port. They were completely loose. Oxygen was coming into the =
exhaust=20
just inches from the O2 sensor. Murphy's law again I guess. After =
tightening I=20
took it for a quick drive. The butt scan said it was running much =
better. I=20
took it for a quick second drive with proper scan tool attached. Much =
better!=20
Idle is still at 160 but all the surrounding rpm/kPa ranges are =
yielding=20
130-145 BLMs.<BR><BR>I feel like I am now getting somewhere. Thanks =
for the=20
exhaust leak tip...<BR><BR>Mike<BR><BR>At 05:50 PM 1/1/2005, you =
wrote:<BR>
<BLOCKQUOTE class=3Dcite cite=3D"" type=3D"cite"><FONT face=3Darial =
size=3D2>I have=20
had trouble with the AIR system bleeding air into the exhaust even =
with the=20
valve "off". Had to plug off the air line whlie tuning. Once I =
had the=20
idle set, and re-connected everything, it would creep to =
ritch. Had to=20
replace the valve in the end. Also had problems with the =
exhaust=20
manifold not sealing at the head on another vehicle and giving lean =
readings=20
on the o2 sensor. Idle blocks are hard to tune, in my opinion, =
since=20
they have to be lean to pass smog.<BR></FONT> <BR><FONT =
face=3Darial=20
size=3D2>--Karl</FONT> <BR>
<DL>
<DD>----- Original Message ----- <BR>
<DD>From:</B> <A href=3D"mailto:mfrels at ix.netcom.com">Mike =
Frels</A> <BR>
<DD>To:</B> <A href=3D"mailto:diy_efi at diy-efi.org">A list for =
Do-It-Yourself=20
EFI</A> <BR>
<DD>Sent:</B> Saturday, January 01, 2005 5:42 AM<BR>
<DD>Subject:</B> Re: [Diy_efi] Re: (was: IAC counts) VE tuning=20
issues<BR><BR>
<DD>I was reading HELMS this morning(couldn't keep the eyelids =
open past=20
11:00 last night) AIR should only inject into the exhaust =
manifolds when=20
cold and in open loop to help burn converter destroying unburned =
fuel.=20
When it warms and goes closed the AIR should then divert to the =
converter.=20
I interpret this to mean the AIR system should have no influence =
on my 02=20
readings.<BR><BR>
<DD>Just the same I am going to double check for proper operation =
today.=20
Hmmm...could I have switched the two connectors to the diverter =
valve last=20
time I reassembled after checking lifter preload?...I've done =
worse=20
before!...<BR><BR>
<DD>I will report on progress as it happens. Yesterday's forecast =
for=20
today was 50% chance of rain.<BR><BR>
<DD>Happy New Year,<BR>
<DD>Mike<BR><BR>
<DD>At 10:04 PM 12/31/2004, you wrote:<BR>
<BLOCKQUOTE class=3Dcite cite=3D"" type=3D"cite">
<DD>that may be the problem... while tuning, plug the AIR system =
as it=20
injects air to the exhaust like a giant leak...<BR>
<DD><BR>
<DD><BR>
<DD>-------Original Message-------<BR></I>
<DD><BR>
<DD>From:</I></B> <A href=3D"mailto:mfrels at ix.netcom.com">Mike=20
Frels</A><BR>
<DD>Date:</I></B> 12/31/04 21:54:09<BR>
<DD>To:</I></B> <A href=3D"mailto:diy_efi at diy-efi.org">A list =
for=20
Do-It-Yourself EFI</A><BR>
<DD>Subject:</I></B> Re: [Diy_efi] Re: (was: IAC counts) VE =
tuning=20
issues<BR>
<DD><BR>
<DD>Don't you mean 'injectors are much SMALLER than #24 they are =
supposed to be?'<BR>
<DD><BR>
<DD>Anyway as far as oxygen getting into the exhaust stream the =
only=20
thing I<BR>
<DD>have really checked is proper AIR system operation. That is =
working=20
as it<BR>
<DD>should. I have not re-checked that exhaust manifold bolts =
since=20
spring when<BR>
<DD>I put the engine in. Yes, I am still running cast iron =
manifolds. I=20
will<BR>
<DD>take a wrench to the exhaust bolts and nuts tomorrow. Thanks =
for=20
that<BR>
<DD>possible pointer.<BR>
<DD><BR>
<DD>The injectors are brand new Accel 24 pounders. No, I did not =
have=20
them<BR>
<DD>flowed before installing as I believed I could trust them =
from the=20
factory.<BR>
<DD>Is experience counter to this?<BR>
<DD><BR>
<DD>Mike<BR>
<DD><BR>
<DD>At 05:59 PM 12/31/2004, you wrote:<BR>
<DD>>I look at it this way: BLM's greater than 128 =
means the=20
ECM is having to<BR>
<DD>>add fuel to keep the mixture right. This means =
it's=20
getting more air than<BR>
<DD>>it should according to the VE tables, which means the =
table=20
values need to<BR>
<DD>>be raised by the appropriate factor. =
[(BLM/128)*current=20
VE] is a very<BR>
<DD>>good formula for finding how much to adjust it.<BR>
<DD>><BR>
<DD>>If you're getting 160 BLM's and you have 80's in the =
low-rpm VE=20
table,<BR>
<DD>>then either your injectors are much bigger than the 24# =
that you=20
think<BR>
<DD>>they are, or you have a pretty significant vacuum leak, =
or=20
you're getting<BR>
<DD>>a false lean reading from the O2. First thing to =
do is=20
check for exhaust<BR>
<DD>>leaks before/near the O2, as that will REALLY screw with =
your=20
BLMs. Where<BR>
<DD>>did you get the injectors? Are they new or used, =
and have=20
they been flow<BR>
<DD>>tested?</DD></BLOCKQUOTE><BR>
<HR>
</DD></DL></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>
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