[Diy_efi] desperate need of help

Programmer nwester at eidnet.org
Wed May 28 03:29:30 GMT 2003


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>> I have spoken to
> them many times and cannot get any answers for my
> problem.  The engine idles pretty good in open loop.=20
> Once in closed loop the idle will not stabilize.  It
> will surge up and down about 200 rpm.  I have checked
> for a vacuum leak and have none.  The block learns are
> around 114 at idle and map kpa is about 44.  The iac
> counts stay steady around 20 to 24 counts.  Under no
> load in park while holding the accelerator steady
> about 1500rpm the rpm will flucuate up and down about
> 100 rpm.<<

That's a characteristic of a slow O2 sensor. Depending on where
you've got the O2 placed, it may never get any better than that.

>>  The engine runs well under load.  I have
> checked the usual things like compression, valve adj.
> vacuum is good at around 21 in hg.  I spent time
> drifting propane around all vacuum fittings and into
> the crankcase to check for a leak under the intake. I
> can't find one.  I need help to determine what the
> problem is and how I can go about fixing it.  I wound
> appreciate any input.
>=20
> Thanks,
> Mike Opp

Your only solution may be an open loop calibration (at idle). Disconnect =
the O2
sensor and see if your "surge" is gone.

Lyndon.
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<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Diso-8859-1">
<META content=3D"MSHTML 6.00.2800.1106" name=3DGENERATOR>
<STYLE></STYLE>
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<BODY>
<DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial =
size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial><BR><FONT size=3D2></FONT></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>&gt;&gt;&nbsp;I have spoken to<BR>&gt; =
them many=20
times and cannot get any answers for my<BR>&gt; problem.&nbsp; The =
engine idles=20
pretty good in open loop. <BR>&gt; Once in closed loop the idle will not =

stabilize.&nbsp; It<BR>&gt; will surge up and down about 200 rpm.&nbsp; =
I have=20
checked<BR>&gt; for a vacuum leak and have none.&nbsp; The block learns=20
are<BR>&gt; around 114 at idle and map kpa is about 44.&nbsp; The =
iac<BR>&gt;=20
counts stay steady around 20 to 24 counts.&nbsp; Under no<BR>&gt; load =
in park=20
while holding the accelerator steady<BR>&gt; about 1500rpm the rpm will =
flucuate=20
up and down about<BR>&gt; 100 rpm.&lt;&lt;</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>That's a characteristic of a slow O2 =
sensor.=20
Depending on where</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>you've got the O2 placed, it may never =
get any=20
better than that.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>&gt;&gt;&nbsp; The engine runs well =
under=20
load.&nbsp; I have<BR>&gt; checked the usual things like compression, =
valve=20
adj.<BR>&gt; vacuum is good at around 21 in hg.&nbsp; I spent =
time<BR>&gt;=20
drifting propane around all vacuum fittings and into<BR>&gt; the =
crankcase to=20
check for a leak under the intake. I<BR>&gt; can't find one.&nbsp; I =
need help=20
to determine what the<BR>&gt; problem is and how I can go about fixing =
it.&nbsp;=20
I wound<BR>&gt; appreciate any input.<BR>&gt; <BR>&gt; Thanks,<BR>&gt; =
Mike=20
Opp<BR></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Your only solution may be an open loop =
calibration=20
(at idle). Disconnect the O2</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>sensor and see if your "surge" is=20
gone.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>Lyndon.</DIV></FONT></BODY></HTML>

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