Quad-4 (1228707 ECM) Rough Idle Problem

Fri Apr 7 03:38:49 GMT 2000

In 89 there were 200 W41 HO quad 4 Calaiz GT's built, all were bright red
with grey cloth and 5 speeds with shorter 5th gear.  I had one brand new as
a Co car.  My mom bought another as a dealer demo.  Great Car!

The the Acheiva SCX was a showroom stock homologation  special with the W41
engine.  You need to find the prom app that matches your ecm.

Mark
-----Original Message-----
From: remaklus at attglobal.net <remaklus at attglobal.net>
To: gmecm at diy-efi.org <gmecm at diy-efi.org>
Date: Thursday, April 06, 2000 5:34 PM
Subject: Re: Quad-4 (1228707 ECM) Rough Idle Problem

>Shannen,
>
>The ECM is correct for the engine. Unfortunately, I have not yet been
>able to obtain the correct (factory) calibration.  This is because I
>bought the engine more or less new (race team spare).  Hopefully I
>will be able to get a copy of the factory cal.
>
>All of the sensors came with engine and are likely the same as the
>HO 2.3.  One problem which makes this more difficult to solve is
>that GM did not produce very many vehicles with the W-41 (190 HP)
>Quad-4 engine.  The HO 2.3 (180 HP) is plentiful, but not the W-41.
>
>When I finally get this engine to idle smoothly (and more importantly
>pass emissions), I look forward to tweaking the calibration to see
>if I can improve things.
>
>-Will
>
>Shannen Durphey wrote:
>
>> 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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