Quad-4 (1228707 ECM) Rough Idle Problem

Fri Apr 7 05:50:59 GMT 2000

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 at hotmail.com>
>Reply-To: gmecm at diy-efi.org
>To: gmecm at 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 at grolen.com>
>>Reply-To: gmecm at diy-efi.org
>>To: gmecm at 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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