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
Check Engine Light/Surging Idle
Topic Started: Oct 1 2017, 12:22 PM (308 Views)
pyratenomad
Trying To Figure Out This Little Car....
[ *  * ]
1998 3/5

Up to now, my Metro has been running great. Today, after a 15 mile, in town drive, the check engine light went on. I got home and let it rest for a little while and went to start it and it didn't want to idle and idled rough. After a few seconds, it started to idle ok, but lightly surging.

I pulled the plugs one at a time and all cylinders were firing, but the engine seems to shake a bit more than it has in the past.

This could be something simple, but I have no OBD reader to check the codes.

I know that I have not given you much info to work with, but I figured that someone on here has experienced these same symptoms at some point.

Thanks in advance.
Offline Profile Quote Post Goto Top
 
MR1 Kingsbury
Member Avatar
Exp. builder/rebuilder

sounds like vacuum leak or MAP sensor failure/clog/leak.
Offline Profile Quote Post Goto Top
 
freegeo
Member Avatar


Drive the car to a auto parts store that checks codes for free. Make sure you get the actual code, not just a description. That would be a good place to start.
Offline Profile Quote Post Goto Top
 
pyratenomad
Trying To Figure Out This Little Car....
[ *  * ]
Just got back from O'reilly's and it turns out to be a PO420 code. Maybe in need of a new cat?
Edited by pyratenomad, Oct 1 2017, 01:38 PM.
Offline Profile Quote Post Goto Top
 
Dystopiate666
Member Avatar
Tree Banger

Not sure the Cat Code relates to surging. That one is telling you the rear o2 doesn't see enough of a change from the first one, as in the cat isn't doing its job anymore (or less likely you have a bad 02 sensor)

Usually surging is from vacuum leaks, TPS or MAP sensor.

I think most people start by changing out vacuum lines and cleaning the grounds on the back of the throttle body.
Offline Profile Quote Post Goto Top
 
pyratenomad
Trying To Figure Out This Little Car....
[ *  * ]
Dystopiate666
Oct 1 2017, 03:48 PM
Not sure the Cat Code relates to surging. That one is telling you the rear o2 doesn't see enough of a change from the first one, as in the cat isn't doing its job anymore (or less likely you have a bad 02 sensor)

Usually surging is from vacuum leaks, TPS or MAP sensor.

I think most people start by changing out vacuum lines and cleaning the grounds on the back of the throttle body.
Thanks for the info. I still have a LOT to learn. Usually, when people here reference a particular part, I have to research what it is and where it is. After that, I have to try and locate it on the car. This can be difficult when the pics that I see are shiny, clean engines and what I am actually looking at under my hood is an old, dirty engine. :)

With all the help that I am getting here, I will be able to figure all these problems out. I really appreciate it, folks.

Hopefully, with all this new information and experience, I can help someone else out on down the road.

Now to locate and check those vacuum lines and figure out what and where this MAP thing is....
Offline Profile Quote Post Goto Top
 
ptcapboy


I think the MAP sensor is quite close to the windshield wiper motor
Offline Profile Quote Post Goto Top
 
pyratenomad
Trying To Figure Out This Little Car....
[ *  * ]
ptcapboy
Oct 1 2017, 04:09 PM
I think the MAP sensor is quite close to the windshield wiper motor
Yes. Thanks. I looked there and that is exactly where I found it. A bit smaller than I expected.
Offline Profile Quote Post Goto Top
 
Dystopiate666
Member Avatar
Tree Banger

The vac lines are all the little rubber hoses you can see connecting the different components on top of the engine, if you follow them, they all have a source on the throttle body or air intake. To replace them, you simply pull off one end, follow it to the other, pull that end off, cut a length of hose with matching inside diameter and reattach, then move on to the next one.

It sounds tedious because it is, but it is easy and will only help your engine performance. Do them one at a time so you don't mix any up, and if you do get confused you can use the diagram on the underside of the hood for reference, or ask for one here.

The grounds on the back of the throttle body are even easier to address. The throttle body is directly under the air intake (air filter housing). Remove the wingnut on top of the air filter, one hose clamp and the four clips holding the top part on. Then under the air filter, there are (I believe ) 2 more nuts holding the bottom part on, plus a sensor connection. Once you have that off, you are looking right down the throttle. On the back of the throttle body, the side closest to the firewall, there are two 10mm bolts holding wire terminals. These are the grounds for all your major sensors. Undo the bolts, and clean the terminals and the mounting surface of the throttle body with a wire brush, then button back up.

Although slightly time consuming, these two tasks require no technical knowledge and will almost certainly improve performance on our often neglected little engines. If you still have the surging after doing the hoses and grounds, then its time to start digging deeper, which will require basic multimeter skills.
Offline Profile Quote Post Goto Top
 
pyratenomad
Trying To Figure Out This Little Car....
[ *  * ]
Thanks for taking the time to write that out for me. I will attack that this weekend.

I notice that the throttle body is really dirty when I look down in to it and also around the edges. What would be the best way to clean that?
Offline Profile Quote Post Goto Top
 
freegeo
Member Avatar


Use a sensor safe throttle body or carb cleaner. Start the engine and spray it in it to clean it up. You will probably need to rev the engine up some to keep it from dying.
Offline Profile Quote Post Goto Top
 
pyratenomad
Trying To Figure Out This Little Car....
[ *  * ]
Well, I took the advice offered here with great success. I pulled the EGR valve, gave it a good cleaning and replaced it with a fresh gasket.
While preparing the throttle body for cleaning, I found 2 disconnected vacuum hoses. Reconnected those.

The little motor sounds a bit better now. :)

Offline Profile Quote Post Goto Top
 
freegeo
Member Avatar


Glad to hear you got it sorted out. Thanks for the response, it helps those in the future that read this to know the outcome.
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