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Unread 01-29-2013, 10:10 AM   #1
DoctorBill
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1989 MJ Comanche 
 
Join Date: Jan 2013
Location: Spokane, WA
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Is my '89 Comanche's Idle controlled by Computer ?

I have tried to set the Idle on my Straight Six '89 Comanche 4x4 via that
screw on the Lever Post, but the idle remains at 1,000 rpm.

THEN - once in a while (seldom) drops to about 600 rpm ! (?)

Is the idle kept where the computer wants it to be - am I wasting my time
trying to adjust it ?

DoctorBill



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Unread 01-29-2013, 03:46 PM   #2
cruiser54
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Yes. Get it back to stock using the following instructions. Then, get to the real root of the problem. TPS? Bad oxygen sensor? Poor sensor grounds?

Cruiser’s Renix Throttle Body Butterfly Adjustment

Okay. Let's start from scratch. First off, that's not an idle adjustment screw. It's a throttle butterfly stop screw. It's purpose is to allow the butterfly to be as close to completely closed as it can be without binding or wearing into the throttle body. It was never intended to be adjusted in the field. But, Uncle Bob didn’t know that, did he?

Engine off. Back off the butterfly stop screw with a 3/32” allen wrench until the butterfly is completely closed. Now. turn the screw in until the FAINTEST movement of the butterfly opening is detected. This can be done more easily with the throttle body removed. If you remove the throttle body, be sure to replace the gasket underneath it after thoroughly cleaning the old one off.

Revised 07/07/2012
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Unread 02-02-2013, 08:10 AM   #3
DoctorBill
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A mechanic looked at the engine yesterday and found that the hard vacuum vapor tube
from the rear of the valve cover up to the front right side throttle body was not connected.

The Chilton Manual (p 4-27) first line says "Verify that there are no vacuum leaks...."



The right angle rubber connector at the throttle body is all floppy and loose - the rubber has degenerated.
Red Arrows in diagram.

He said that a vacuum leak there allows an electronic valve inside throttle body (the IAC),
that controls the throttle at Idle, can't adjust properly with a vacuum leak there.
Probably causing the high idle speed.

A new Vapor Tube assembly costs $27, and I give a s**t about environmental oil vapor leaks -
so I am going to plug up the barb on the throttle body to stop the vacuum leak.

Also the larger oil vapor tube assembly at the front of the Valve Cover (over to the air filter)
is all shot with age - THAT assembly costs around $75 if I remember right....
I'll let that alone - no big deal - just feeds into the Air Filter Canister. Blue Arrow.

I'll let you know what happens....

DoctorBill
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Last edited by DoctorBill; 02-02-2013 at 08:27 AM..
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Unread 02-02-2013, 10:41 AM   #4
DoctorBill
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Plugging the Vacuum tube from the previous post did the trick - the Idle is back to where it
should be, below 1,000 rpm.



The rubber right angle connector was replaced with gas line tubing (A) and
plugged inside with a wood dowel and reconnected to the rigid Vacuum line
going to the back of the Valve Cover.

That stopped the Throttle Idle Advance Valve (C) from opening the throttle (D)
too much.

The Oil Vent Tube (B) is broken - was taped, but the tape became gooey and fell off.
I'll re-tape it and wrap it with wire. Too expensive to replace !
Maybe a Wrecking Yard might have one - (?)

All is well now....

DoctorBill
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Unread 02-02-2013, 11:31 AM   #5
cruiser54
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Somebody's blowing smoke about the prices.

Renix Vacuum Harnesses

The vacuum harness that attaches to the front of the valve cover and includes the grommet/fitting, and is called the front harness, is Napa part number BK 715-1367


http://www.napaonline.com/Catalog/Ca...367_0269070623


The vacuum harness that is closest to the air cleaner, EGR etc, and is called the rear harness, is Napa part number BK-715-1366.

http://www.napaonline.com/Catalog/Ca...366_0269070622


The tube from the rear of the valve cover to the intake manifold is part number 715-1365.

http://www.napaonline.com/Catalog/Ca...365_0066877355


Revised 09-11-2012
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Unread 02-02-2013, 05:03 PM   #6
DoctorBill
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cruiser54 - NONE of the links or Part Numbers you show bring up anything on NAPA except "ERROR" !

"We're sorry, an error has occurred. We are working to resolve it. Please try your request again."

Going to the NAPA web site and entering the Part Numbers you gave me
bring up _ "Not Found".

BK 715-1367 for instance. In general or for 1989 Jeeps.

I don't know where you are getting this from, but I sure can't get to it....

DoctorBill
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Unread 02-02-2013, 05:11 PM   #7
cruiser54
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Quote:
Originally Posted by DoctorBill View Post
cruiser54 - NONE of the links or Part Numbers you show bring up anything on NAPA except "ERROR" !

"We're sorry, an error has occurred. We are working to resolve it. Please try your request again."

Going to the NAPA web site and entering the Part Numbers you gave me
bring up _ "Not Found".

BK 715-1367 for instance. In general or for 1989 Jeeps.

I don't know where you are getting this from, but I sure can't get to it....

DoctorBill
Call your local Napa with the numbers then. The links used to work. I just bought the one from the valve cover to intake manifold and comes with the grommet. $11 last week.
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Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
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Unread 02-02-2013, 07:39 PM   #8
DoctorBill
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cruiser - I will look into that.

Question though - what purpose does that small vacuum tube serve going to the rear
of the Valve Cover ?

If it sucks oil fumes into the intake manifold - WHY ?

The front large tube going to the Air Intake Filter Canister sucks the oil fumes into the Air Intake -
why the redundancy ?

Oil going into the Intake Manifold serves what purpose ?

DoctorBill
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Unread 02-02-2013, 07:51 PM   #9
cruiser54
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The intake manifold sucks crankcase fumes into the intake manifold through the metered orifice in the rear valve cover grommet/fitting. The air into the valve cover comes through the air filter and into the large fitting on the front of the valve cover.
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Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
Refresh*Connections*Before*Replacing*Components
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