RE: [DML] Re: Tuning Idle Speed Circuit. (was: Re: idle problem)

["John Hervey" <john@xxxx>]

Rustproof, See below.My 2 Cents.
John Hervey


-----Original Message-----
From: Rustproof [mailto:Rustproof@xxxx]
Sent: Thursday, August 28, 2003 9:36 AM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: Re: [DML] Re: Tuning Idle Speed Circuit. (was: Re: idle
problem)


Having taken all the advice I could get from the list and the archives, I
have attempted to set up both the CO mixture as well as the CIS idle. This
was fiddled with by the previous owner and never properly reset. I set the
(CO Mixture Screw) air/fuel mixture using an exhaust gas analyzer at 14.1:1
with CO emmission at less than 1%. Idle set was 750 and varied about 50rpms
high and low.

( First I would adjust by ear and set the idle at 950. Makes sure the lower
idle speed screw on the throttle body lever is resting on the stricker plate
and then the upper screw is turned in about 30 thousands and hitting the
microswitch to activate the idle speed motor 1st..)


The frequency valve could be heard at idle at a relatively
constant and stable pitch. ( Good, it should be.)

The engine appeared to run very smoothly.
However, upon shutting it off, it would not restart! I then advanced the
mixture screw by 1/8th turn intervals clockwise until the engine was able to
start. The idle was erratic and fluctuated several hundred RPMs hunting
wildly. The frequency valve buzzed on the lean upswings and was silent on
the downswings. I then adjusted the CO screw (by ear) until the engine ran
smooth again but I could see by the analyzer that it was running on the rich
side to get it to settle down. I then set the idle again to 750. This time
the idle remained on 750 exactly with no fluctuation at all but the
frequency valve remained silent. I assume that this is due to the very rich
mixture. The engine seems to run fine set like this but I realize that I am
essentially nullifying the lambda system with the over-rich mixture.
( The Lambda ECU is electronicly set to enrich untill the 02 kicks in, That
why it's running rich.)

The engine has been checked methodically and no vacuum leaks can be found.
All
o-rings, tubing and fuel system parts including pump, accumulator and hot
start kits are new. The engine has only 8,000 miles on it.

( When you adjusted the 02 about 1/8th turn, Do you know what you did. Was
the engine hot,and did you push down on the tool or just let it rest in the
screw head and turn.)

I was hoping that someone on the list with a pefectly operationg system
might answer the following questions:

1. At idle, should the frequency valve buzz constantly and steadily?
( If everything is properly adjusted my answer would be yes.)


2. With the O2 sensor unplugged, I am able to set up everything exactly to
spec. and the engine runs smooth and perfect. As soon as I reconnect it, it
hunts wildly again and I am forced to adjust the CO mix again to get it to
settle down! Why is this happening?
( Your doing a manuel adjustment and the 02 does it electronicly.The 02 it's
going to monitor it every step of the way which is what it's supposed to
do.You just have to get to the 14.0 to 1 so there will be very little swing
by the 02 to the Lambda ECU to the FV.)

3. At 750 idle, should the CIS adjust to compensate for the A/C load or does
the idle normally drop 100 RPMs.
( The CIS,??? has nothing to do with the extra load.Not for sure what you
mean Should the CIS compensate.)

Your input will be greatly appreciated!
Thanks,
Rustproof
Vin #1559





> To address comments privately to the moderating team, please address:
> moderators@xxxx
>
> For more info on the list, tech articles, cars for sale see
www.dmcnews.com
>
> To search the archives or view files, log in at
http://groups.yahoo.com/group/dmcnews
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>




To address comments privately to the moderating team, please address:
moderators@xxxx

For more info on the list, tech articles, cars for sale see www.dmcnews.com

To search the archives or view files, log in at
http://groups.yahoo.com/group/dmcnews

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/