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Re: Quad-4 (1228707 ECM) Rough Idle Problem



Ah, sigh . . . (or is that "grunt"?)

I still stand by my message (below) of a few minutes ago, but when I saw the FTP URL - and I expected a WWW URL - I should have checked . . .

<http://www.se-r.net/about/200sx/scc/july97/july.html>

. . . is thw _WWW_(!) URL for the article with the seemingly wrong information. (What?, wrong information in the WWW?)

I'm still soliciting any input on this question,

thanks,
Mike


From: "mike mager" <mikemager@hotmail.com>
Reply-To: gmecm@diy-efi.org
To: gmecm@diy-efi.org
Subject: Re: Quad-4 (1228707 ECM) Rough Idle Problem
Date: Thu, 06 Apr 2000 22:33:56 PDT

Uh, did anybody else catch that (or do I need better drugs?)?
[complete quotation below]

[this is quoted from the FTP site:]
<ftp://ftp.diy-efi.org/incoming/Quad-4%20Idle%20Miss.pdf>

"Very high overlap cams will exhibit an "eight stroking" phenomena . . . "

Sure, well known, and a two-stroke-cycle may analogously 'four-stroke'.

" . . . pumping out a cylinder full of unburned gas . . . "

Alright, lotsa unburned fuel (HC), sure
              - but -
lotsa unburned _air_(!). (at ~20% O2!)

"The over-rich exhaust will not contain enough oxygen for the catalytic
converter . . . "

Here it is - What?
The unburned air is ~20% oxygen, radically more than _any_ combustion event
could _ever_ put out!  The EGO reads the oxygen (O) in the exhaust (E) gas
(G), not the HC.

<brag>
Ima ASE certified drivability mechanic, and . . .
</brag>

It is common for a plain-old Motor City rig to have the EGO read a dead miss
as a too-lean condition, just _because_ of that ~20% O2 in the unburned air
after a misfire.

What are they getting at?  (or what did I miss?)

Mike (an IR intake helps to 'tame' high overlap)


From: Shannen Durphey <shannen@grolen.com>
Reply-To: gmecm@diy-efi.org
To: gmecm@diy-efi.org
Subject: Re: Quad-4 (1228707 ECM) Rough Idle Problem
Date: Thu, 06 Apr 2000 19:08:16 -0400

Will, I've got a few questions.

1) I know you've mentioned this, but please tell me again:  Do you
have the correct calibration and ecm that was originally used with the
HO 2.3 engine?  Is this what you are using now, while you
troubleshoot?

2)  Are all your sensors the same as the HO 2.3 engine?  How different
is your configuration from the factory HO car?

3)  Have you spoken to anyone that has a vehicle that was originally
released with this engine?  Do they have the same problems?

Shannen
Will Remaklus wrote:
>
> david garnier wrote:
>
> > I haven't been paying all the close to this thread, I
> > appologize if I am off base...
> >
> > I have seen rough, unsteady or idle that never seems
> > to smoothly come down, until maybe the engine starts
> > to warm up.  Dumb question, when was the last time
> > you removed your IAC and cleaned the pintle and
> > mating seat with gas or cab cleaner?  I am amazed at
> > the difference cleaing the pintle and seat will do on
> > idling.
>
> I pulled the throttle body about a month ago and cleaned
> it and the IAC pintle.  There was very little build up
> to remove and hence I did not get any improvement.
>
> Here are some new findings on the problem:
>
> In pursuit of trying to understand my rough idling problem I
> decided that the 2X reference pulses from the ignition module
> did not provide enough resolution.  Therefore, several weeks ago
> I fabricated a 24 slot crank position sensor using an IR LED and
> photodetector.  The .pdf file:
>
>  ftp://ftp.diy-efi.org/incoming/Quad-4%20Idle%20Miss.pdf
>
> shows the instantaneous RPM, that is RPM calculated based on the
> time between two adjacent slots in the wheel, versus time.  I also
> included the slot number off the wheel to aid in identifying the
> relative position of the crank.
>
> The first page is the engine at idle.  Notice that it appears
> that all four cylinders fire, followed by two revolutions of
> little if any power.  In contrast, the second plot, at 1900 RPM,
> shows a much better situation: an increase in crank speed as each
> cylinder fires.  At first I thought that the engine control
> computer was causing this, but now I am pretty sure that is
> not the case.
>
> While surfing the net I located the following:
>
>   Very high overlap cams will exhibit an "eight stroking"
>   phenomena at idle where each cylinder will completely misfire
>   on every other compression stroke...  This phenonmenon is
>   responsible for the loping idle of the older hot-rod V-8s.
>   Unfortunately, with every other exhaust stroke pumping out
>   a cylinder full of unburned gas, hydrocarbon emissions soar.
>   The over-rich exhaust will not contain enough oxygen for the
>   catalytic converter to complete its breakdown of unburned
>   hydrocarbons, so even with the cat in place it will become
>   ineffective.
>
> The above explanation seem to perfectly describe the problem
> that I am having.  The exhaust is very rich, yet the catalytic
> converter is not all that hot (or glowing red, like it did
> years ago when I had an ignition coil go bad!).
>
> Therefore, it appears that the problem is likely caused by
> something in the top end.  When I checked the timing chain
> several weeks ago I verified that at TDC the camshaft alignment
> dowel pins went in easily.  As such, the only things left to
> check are the lifters and the cams.
>
> Any ideas?
>
> -Will


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