[Diy_efi] Re: (was: IAC counts) VE tuning issues

Mon Jan 3 02:05:44 GMT 2005

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I don't think a non-heated O2 Sensor is my 160 problem. My BLM goes to 160 
almost the instant, if not slightly before, my engine goes to idle. I just 
can't see the sensor cooling off THAT fast. I've got a used four wire 
heated O2 sensor from a fourth-gen F-body that I plan to install but I 
don't want to introduce any more variables at this time.

My idle counts are staying around 11 and my MAP Sensor doesn't indicate a 
vacuum leak so I am going to do some more looking for oxygen leaks into the 
exhaust manifold and another plumbing which goes into the exhaust 
manifolds. It's gotta be something as stupidly simple as those backed off 
manifold bolts. Perhaps a crack in the cast iron or a cracked AIR tube 
weld...hmmmm...

Mike

At 03:55 PM 1/2/2005, you wrote:
>you can avoid the O2 cooldown problem by installing a heated O2... run the 
>heater from Switched 12V and ground
>
>
>-------Original Message-------
>
>From: <mailto:charles at taildragger.info>Charles McDowell
>Date: 01/02/05 16:33:49
>To: <mailto:diy_efi at diy-efi.org>'A list for Do-It-Yourself EFI'
>Subject: RE: [Diy_efi] Re: (was: IAC counts) VE tuning issues
>
>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.
>
>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.
>
>--Karl
>----- Original Message -----
>From: <mailto:mfrels at ix.netcom.com>Mike Frels
>To: <mailto:diy_efi at diy-efi.org>A list for Do-It-Yourself EFI
>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...
>
>
>-------Original Message-------
>
>From: <mailto:mfrels at ix.netcom.com>Mike Frels
>Date: 12/31/04 21:54:09
>To: <mailto:diy_efi at diy-efi.org>A list for Do-It-Yourself EFI
>Subject: Re: [Diy_efi] Re: (was: IAC counts) VE tuning issues
>
>Don't you mean 'injectors are much SMALLER than #24 they are supposed to be?'
>
>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.
>
>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?
>
>Mike
>
>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?

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<body>
I don't think a non-heated O2 Sensor is my 160 problem. My BLM goes to
160 almost the instant, if not slightly before, my engine goes to idle. I
just can't see the sensor cooling off THAT fast. I've got a used four
wire heated O2 sensor from a fourth-gen F-body that I plan to install but
I don't want to introduce any more variables at this time. 
My idle counts are staying around 11 and my MAP Sensor doesn't indicate a
vacuum leak so I am going to do some more looking for oxygen leaks into
the exhaust manifold and another plumbing which goes into the exhaust
manifolds. It's gotta be something as stupidly simple as those backed off
manifold bolts. Perhaps a crack in the cast iron or a cracked AIR tube
weld...hmmmm... 
Mike 
At 03:55 PM 1/2/2005, you wrote: 
<blockquote type=cite class=cite cite="">you can avoid the O2 cooldown
problem by installing a heated O2... run the heater from Switched 12V and
ground 
&nbsp; 
&nbsp; 
-------Original Message------- 
&nbsp; 
From: <a href="mailto:charles at taildragger.info">Charles
McDowell</a> 
Date: 01/02/05 16:33:49 
To: <a href="mailto:diy_efi at diy-efi.org">'A list for
Do-It-Yourself EFI'</a> 
Subject: RE: [Diy_efi] Re: (was: IAC counts) VE tuning
issues 
&nbsp; 
Let us know if you figure out
the idle.&nbsp; I also have what seems to be excessively high BLM right
at idle.&nbsp; 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.&nbsp; 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.&nbsp; 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).&nbsp; Or possibly it just needs
more VE.&nbsp; I have to work on it to see, but I'd be curious what you
figure out. 
&nbsp; 
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.&nbsp; Is
this why they have it, because closed loop is flakey at idle?&nbsp; 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
[<a href="mailto:diy_efi-bounces at diy-efi.org" eudora="autourl">
mailto:diy_efi-bounces at diy-efi.org</a>] 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 &quot;off&quot;. Had to plug off
the air line whlie tuning.&nbsp; Once I had the idle set, and
re-connected everything, it would creep to ritch.&nbsp; Had to replace
the valve in the end.&nbsp;&nbsp; Also had problems with the exhaust
manifold not sealing at the head on another vehicle and giving lean
readings on the o2 sensor.&nbsp; Idle blocks are hard to tune, in my
opinion, since they have to be lean to pass smog. 
&nbsp; 
--Karl 
<dl>
<dd>----- Original Message ----- 
<dd>From: <a href="mailto:mfrels at ix.netcom.com">Mike Frels</a> 
<dd>To: <a href="mailto:diy_efi at diy-efi.org">A list for Do-It-Yourself
EFI</a> 
<dd>Sent: Saturday, January 01, 2005 5:42 AM
<dd>Subject: Re: [Diy_efi] Re: (was: IAC counts) VE tuning issues

<dd>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.

<dd>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!...

<dd>I will report on progress as it happens. Yesterday's forecast for
today was 50% chance of rain.

<dd>Happy New Year,
<dd>Mike<br>

<dd>At 10:04 PM 12/31/2004, you wrote:
<dd>that may be the problem... while tuning, plug the AIR system as it
injects air to the exhaust like a giant leak...

<dd>&nbsp; <br>

<dd>&nbsp; 
<dd>-------Original Message-------<br>

<dd>&nbsp; 
<dd>From: <a href="mailto:mfrels at ix.netcom.com">Mike Frels</a>
<dd>Date: 12/31/04 21:54:09
<dd>To: <a href="mailto:diy_efi at diy-efi.org">A list for Do-It-Yourself
EFI</a>
<dd>Subject: Re: [Diy_efi] Re: (was: IAC counts) VE tuning issues<br>

<dd>&nbsp; 
<dd>Don't you mean 'injectors are much SMALLER than #24 they are supposed
to be?'<br>

<dd>&nbsp; 
<dd>Anyway as far as oxygen getting into the exhaust stream the only
thing I
<dd>have really checked is proper AIR system operation. That is working
as it
<dd>should. I have not re-checked that exhaust manifold bolts since
spring when
<dd>I put the engine in. Yes, I am still running cast iron manifolds. I
will
<dd>take a wrench to the exhaust bolts and nuts tomorrow. Thanks for
that
<dd>possible pointer.

<dd>&nbsp; 
<dd>The injectors are brand new Accel 24 pounders. No, I did not have
them
<dd>flowed before installing as I believed I could trust them from the
factory.
<dd>Is experience counter to this?

<dd>&nbsp; 
<dd>Mike<br>

<dd>&nbsp; 
<dd>At 05:59 PM 12/31/2004, you wrote:
<dd>&gt;I look at it this way:&nbsp; BLM's greater than 128 means the ECM
is having to
<dd>&gt;add fuel to keep the mixture right.&nbsp; This means it's getting
more air than
<dd>&gt;it should according to the VE tables, which means the table
values need to
<dd>&gt;be raised by the appropriate factor.&nbsp; [(BLM/128)*current VE]
is a very
<dd>&gt;good formula for finding how much to adjust it.
<dd>&gt;
<dd>&gt;If you're getting 160 BLM's and you have 80's in the low-rpm VE
table,
<dd>&gt;then either your injectors are much bigger than the 24# that you
think
<dd>&gt;they are, or you have a pretty significant vacuum leak, or you're
getting
<dd>&gt;a false lean reading from the O2.&nbsp; First thing to do is
check for exhaust
<dd>&gt;leaks before/near the O2, as that will REALLY screw with your
BLMs.&nbsp; Where
<dd>&gt;did you get the injectors?&nbsp; Are they new or used, and have
they been flow
<dd>&gt;tested?
</dl></blockquote></body>
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