Last post on Nov 27, 2013 at 12:52 PM
You are in the Chevrolet Metro/Geo Metro
What is this discussion about?
Geo Metro, Chevrolet Metro, Hatchback
#1179 of 1867 Re: Coil-resister or not? [zaken1]
Sep 27, 2007 (9:40 am)
I also want to add that there are two common mistakes which lead to Geo Metro engines burning valves. One can happen if the ignition timing is adjusted without first disconnecting and plugging the vacuum lines to the two advance diaphragms. Not disconnecting those vacuum lines will result in the timing being set about 8 degrees retarded from the factory specification. And that's a guaranteed valve burner.
The second mistake that can lead to Metro engines burning valves is to use the wrong spark plug heat range. Metro engines are more sensitive to plug heat range selection than probably any other stock engine out there. If you choose a spark plug from a cross-reference chart that compares it to another brand, there is a good chance you'll end up with the wrong plug. It's even worse if you use a particular plug in the Metro because it worked well in another type of engine. The ONLY safe way to select a plug is to look up your vehicle make, year, and engine model in a catalog published by the manufacturer of the same brand of plug that you intend to use.
I have owned a 1990 Metro for the last 15 years, during which I have put nearly 200,000 miles on the engine. It has never burned a valve, or had any other internal engine problem. This is the best engineered vehicle I have ever owned. So I am saddened when I see people reporting problems that I know come from improper maintenance.
#1180 of 1867 Re: stuck and pissed [zaken1]
Oct 07, 2007 (5:58 pm)
I have a 96 metro 1.3 liter with the same problem. I have changed the engine, timing belt, crank sensor, and still have the 4 sparks then nothing. Changed the ECM and nothing. My last hope is to change the cam sensor in the distributor and the pick up. Good luck
#1181 of 1867 Re: stuck and pissed [mailcarrier]
Oct 07, 2007 (8:56 pm)
There is one other possible cause, which I didn't mention in my previous post. The ignition switch may get an open circuit or develop excessive resistance in the "run" position. A switch that has gone bad in this manner may conduct adequately for the first few seconds, until the contacts heat up. Then it quits. Or, maybe the 4 sparks are all being produced while the key is held in the "start" position, and as soon as you release the key, and the switch snaps back to the "run" position, the circuit goes open.
Try keeping the switch held in the start position AFTER the engine fires, and see if it continues to run that way. If it does, you've got an ignition switch with a bad "run" position.
#1182 of 1867 Re: Rough Idle [whitetop]
Oct 12, 2007 (1:49 pm)
hey, I ran into the same problem too, did you fix the problem with the engine rough idle?
I have read somewhere that it could be the fuel injection system.
Your problem is like looking at my car.
#1183 of 1867 Re: Rough Idle [edonis]
Oct 12, 2007 (4:31 pm)
Considering that the "rough idle" message you responded to was originally posted in October of 2005, I don't think it's likely you'll get a reply from him now.
I also have a 3 cyl Metro, which ran well, but idled very roughly, at the time I bought it. The previous owner seemed to think it had always run like that. I've now had that car for 15 years, and have found that the idle quality is very much affected by the brand and type of spark plug being used, and also by the adjustment of the air bypass screw in the throttle body.
My Metro does not run well with NGK plugs. Because they're so popular, I've tried many different gap styles and heat ranges of NGKs, but none of them work as well as either Autolites, Champions, AC, or Bosch. The best all around plug has been the Autolite #63. (Yes, I know that is one heat range colder than the book recommends; but my engine runs and idles best with a slightly cooler plug.) My engine has excellent compression, and is not used for many short trips, so the plugs stay clean. For a car that gets more short trip driving, I'd probably use an AC #R42CXLS, which is the stock recommendation. Another excellent choice would be a Champion Truck plug; either #4430 or #4434. The #4430 is slightly less projected, and would do better on the highway; the #4434 would do better in city driving. Both of the Champion numbers mentioned here require a 5/8" plug socket, while the Autolite and the AC numbers I listed take the 13/16" socket that was standard for the Metro. But those plugs are otherwise completely interchangeable. And I make sure the gap is set to .043". Contrary to popular myth, most plugs do not come with their gap preset for your engine. A given plug will often be used in many different engine types, which do not all use the same gap. Since the Metro has an aluminum cylinder head, it is also very important to apply a light coating of "anti-seize compound" to the plug threads before installation. That will minimize the chance that the plug will bond itself to the head from corrosion. Otherwise, the next time the plug is removed, it might take the aluminum threads from the head out along with it. And that can create a major problem.
But back to the issue of rough idling; once the proper plug is in the engine, and the motor is fully warmed up, readjusting the air bypass screw can make a big difference in idle quality. But be aware; THE IDLE BYPASS SCREW IS A VERY SENSITIVE ADJUSTMENT. Because of this, it is not recommended to try adjusting it unless you are experienced with adjusting fuel mixtures. Sometimes just 1/16 turn can make a big difference, but other times it may be 1 or 2 full turns off.
And, of course, there can be no vacuum leaks in any hoses, and the ignition timing must be set correctly.
I hope this helps.
Oct 12, 2007 (5:01 pm)
I have a 1996 Geo Metro Coupe (2 Door), The running lights work but when I turn the head lights on they turn off but the back lights stay on. Have any ideas that can help me? Thanks
#1185 of 1867 Re: Headlights [chnsaw14]
Oct 12, 2007 (7:50 pm)
This kind of situation is usually caused by a loose or corroded ground connection from the front running light assemblies to the vehicle body. It also might come from the battery negative terminal being grounded to the engine, but not being also connected to the vehicle body.
There should be a dedicated ground wire coming from each of the running light assemblies. Be sure either of them is not broken off or disconnected. And if the ground wire is connected to the body, it would be worth taking the connection apart, cleaning it until it is shiny, and scraping off any rust or paint that might be keeping the connector from pressing on bare metal.
The original battery ground cable goes to a bolt on the engine; this cable also contains a second, smaller wire that is supposed to fasten to a bolt on the fender well. Sometimes people replace the ground cable with one that only goes to the engine. And that makes it very difficult for power coming from the lights to return to the battery. So, if your car does not have a second grounding wire from the battery negative post, you'll need to install a wire going from either the negative battery post, or any clean engine bolt, to any clean bolt on the fender or firewall.
Let me know if this helps. Joel
#1186 of 1867 Re: Rough Idle [zaken1]
Oct 15, 2007 (5:53 pm)
Hey guys - I'm still around, and still driving the same 93 Metro convertible to work every day. I still have some trouble with the rough idle at times, but it's not consistent. I have used several types of plugs. I currently am using Bosch. They seem to work pretty well, but the problem is still there some days. I keep my idle speed cranked up a bit to around 1,000, which helps to smooth it out.
After driving the car for six years I do think it has something to do with a dirty fuel injector system. I periodically run a bottle of fuel injector cleaner through the gas tank and that does more good than anything to clean up the rough idle. I really don't know what to do do make a more permanent solution.
Thanks for the detailed advice. I think my favorite thing about this car is you can drive it forever even when it's not operating at optimal level. My other car wants to shut itself down if you don't screw on the gas cap tight enough.
#1187 of 1867 Re: Rough Idle [whitetop]
Oct 15, 2007 (7:19 pm)
From this distance, it is pretty difficult to sort out a problem of this type. But here are a few more possibilities: If the spark plug wires have developed excessive resistance, that could cause an intermittent rough idle. That can be checked by measuring the resistance of each wire with an ohmmeter. If any wire, including the one from the coil to the distributor cap, has more than 1000 ohms resistance per inch of length, then that wire is bad. I.E. A 14 inch long wire cannot have more than 14,000 ohms resistance. It is best to take each wire out of the distributor cap in order to measure its resistance. Trying to clip a meter probe onto a contact inside the cap can give misleadingly high readings. And be sure the carbon button in the center of the cap is still in place. Sometimes they fall out. That could cause a rough idle, too.
Another possible cause could be a sticking EGR valve. Try (or ask a mechanic) to unbolt the EGR valve and thoroughly clean out the carbon from all the passages. Then work the stem back and forth, until you see that it moves and seats freely.
If the intake manifold or the throttle body bolts have come loose, that could create air leaks which mess up the idle.
Some brands of cheap fuel, or fuel which contains alcohol, can also create a rough idle. If you use the same brand of fuel all the time, try going to another station, or to a higher octane.
And if the coolant thermostat has been removed, the engine will run too cold, and that will mess up the idle quality. Your temperature gauge should run 1/3 to 1/2 way up, under normal conditions.
You say that you keep the idle speed cranked up. I hope you mean you just keep your foot on the gas a little when it is idling. If not, then how did you change the idle speed??? There is no adjustment for the idle speed on that engine. There is a stop for the throttle linkage, which is held in place by a lock nut. But that is not intended to be moved. Moving that stop will upset the air/fuel ratio, and will require resetting both the computer's throttle switch and the idle air bypass screw. And if that is not done, it will create a chronic rough idle.
I would also like to know how rough a 'rough idle' is in your experience. An abnormally rough idle will make the gearshift lever bounce from side to side. Anything less than that in a 3 cylinder car may not be abnormal.
See if any of that makes a difference.
#1188 of 1867 Re: Rough Idle [whitetop]
Oct 16, 2007 (5:21 am)
Sorry for my English
When you change the plugs ... you must change and adjust if necesary the distance between central pin and ground of the plug .
This must be 0.7 mm ( do it with a standard calibrated blade of 0.7 mm )
If there are no changes ... try to adjust the central plugs regulator ( were all wires from plugs are meeting )
Loos the screw and turn easily till the engine have the most hy turation or sounds good .
After that if it's too turated ... adjust the turation from the gas admision screw at the top of the engine .
Good luck and if you need details write me dicectly to e-mail : florinnicolici#ti.slr.com