Welcome Guest [Log In] [Register]
Posted ImageWelcome to the all new Geo Metro Forum. We hope you enjoy your visit.

You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are features you can't use and images you can't see. Registration is simple, fast, and completely free. If you're already a member please log in to your account to access all of our features:

Join our community!




Username:   Password:
Add Reply
95 Geo Metro dies while driving
Topic Started: Sep 27 2017, 01:23 PM (3,426 Views)
Metromightymouse
Member Avatar
Powdercoat Wizard

If the ISC was plugged in, unplug it and drive without it plugged in. If everything is normal (just no choke action ) then I would suspect something with the ISC.
Online Profile Quote Post Goto Top
 
suzukitom
Member Avatar
Tom

When the temporary spacer was in, the ISC idle switch began to function again, controlling the idle speed by moving the plunger in or out as required to maintain 750 rpm. Eventually the ISC plunger position was such that it could not move to where it wanted to be without disengaging the idle switch. This can set up an idle hunting action..ie. surging as the PCM attempts to command the ISC to move, but only when the idle switch is on.

The ISC spacer test was intended to verify:
1. whether the ISC motor works to control idle (yes), and
2.whether the idle switch inside it is operating ( yes), and
3.whether the idle switch is engaging when the throttle plate is closed at the correct idle position (no).

I compare the ISC to a seesaw. The throttle valve must be at a perfectly balanced position so the idle can go up or down
Edited by suzukitom, Nov 8 2017, 07:40 PM.
Offline Profile Quote Post Goto Top
 
freegeo
Member Avatar


suzukitom
Nov 8 2017, 07:37 PM
When the temporary spacer was in, the ISC idle switch began to function again, controlling the idle speed by moving the plunger in or out as required to maintain 750 rpm. Eventually the ISC plunger position was such that it could not move to where it wanted to be without disengaging the idle switch. This can set up an idle hunting action..ie. surging as the PCM attempts to command the ISC to move, but only when the idle switch is on.

The ISC spacer test was intended to verify:
1. whether the ISC motor works to control idle (yes), and
2.whether the idle switch inside it is operating ( yes), and
3.whether the idle switch is engaging when the throttle plate is closed at the correct idle position (no).

I compare the ISC to a seesaw. The throttle valve must be at a perfectly balanced position so the idle can go up or down
I agree. I know it has been done a couple of times, but it would be worth it to check the tps again. Step by step.
Offline Profile Quote Post Goto Top
 
clc
Member
[ *  *  * ]
OK guys. Thanks.
I will drive it around with the ISC disconnected and see if idle and surging change.
I will recheck TPS setting.
suzukitom you said "3.whether the idle switch is engaging when the throttle plate is closed at the correct idle position (no).", how can this be corrected?
Offline Profile Quote Post Goto Top
 
freegeo
Member Avatar


If you need help with the procedure for the tps just ask. There is one for checking and one for adjustment. Both are similar.

For the ECM do things right it needs good inputs for the outputs to be good.
Offline Profile Quote Post Goto Top
 
suzukitom
Member Avatar
Tom

clc
Nov 9 2017, 07:51 AM
suzukitom you said "3.whether the idle switch is engaging when the throttle plate is closed at the correct idle position (no).", how can this be corrected?
The ISC plunger tip must be firmly pressed against its stop, during warm idle. The internal spring inside the ISC plunger is fully compressed, so the idle switch is engaged. If this is not true, the PCM will not command the ISC motor to control idle properly. The nickel you used as a test spacer against the tip of the ISC plunger wasn't able to get the idle switch to engage exactly when the throttle plate is in a closed, idle position.

Read evmetro's post on this thread on adjusting the throttle plate to fully close at idle position. (Note the existing ISC assembly is simply removed to gain access, and reinstalled afterwards.)

http://geometroforum.com/topic/8103585/1/



Offline Profile Quote Post Goto Top
 
1 user reading this topic (1 Guest and 0 Anonymous)
« Previous Topic · Engine Tech & Diagnostics · Next Topic »
Add Reply