Rough Idle

What could be causing my stylish ride to be idling a little rough? Is there something that I can tweak? Or is it just the way of the car?

Here's more information that should help people out. I have a 94 Geo metro with about 171K miles on it. I have only put on 7K of those miles. My engine is the 1.0L not the 1.3L. All work that has been done to it have have done since I got the car back in February. I have very little experience in doing automotive repair. Everything I know I either got from my dad, a manual, or this website. Now along with the rough idle I have noticed a grinding sound. It sounds to me like gears aren't completely meshing. Does anyone know what could be causing this noise?

If your car has A/C, remove the belt and see if that helps.

Are there any other symptoms you can think of? Lack of power, stumbling, backfire, noticeable change in fuel economy?

-MechanicMatt

94's only got the three cylinder, they started putting the four in Metros in '95. The three does idle rough but I'll assume that you've noticed a change. Might just be idling too slow, bad idle air controller or the thingy that compensates for extra load (can't remember what they call that). Bad sparkplug or wire, crusty fuel injector. With 171K miles, I would expect a burned exhaust valve, you don't know if the head has ever been redone since you bought it used. Get a compression check.

Is the grinding sound constant or just when you shift gears? If constant, might be a wheel bearing. If just when you shift, check the clutch adjustment for freeplay. Your pedal should move half an inch or less by hand before you feel the resistance of the clutch. If you stand in front of the driver's seat and look straight down between the distributor and the battery you will see a six inch long lever with a cable connected to it on the battery end. The other end goes into the bellhousing and works the clutch. There's a screw adjustment on the end of the cable. Tighten that up until there's no slack in the cable, then back it off one full turn, maybe one millimeter of slack. Also could be low or wrong transmission fluid, these cars require pretty thin fluid, mechanics often put in standard fluid that's good for most cars. It works in the summer, but when the temperature gets below 30 it gets hard to shift. Needs 75W-90 GM Synchromesh.

I don't have any A/C so I don't have to worry about that belt. I haven't noticed anything that has noticeably cnaged, meaning no lack of power, no stumbling, no backfiring, and absolutely no loss in fuel economy. The only loss in fuel economy I have noticed is when the seasons changed I lost a few mpg's.

It is common for the idle to need to be increased in winter...

If you have a Dwell-Tachometer, or can get one from a friend, you can find
out how fast the car idles.

Mine idles around 1,000 rpm - a bit high, but no worries.....
If yours idles at 500 or so, it will be rough.

If you plan to keep this Metro, consider buying a Chilton or Haynes Manual.

It has pictures....worth a thousand words here. $20 at Schucks or NAPA or most
Automotive Parts Stores.

A Metro with that many miles may, indeed, have burned valves -

BUT - for all you know, the engine may have been overhauled before you
aquired the car!

Do you know ANY of the history of your Metro ?

The older Geo Metro 3 cylinder cars are FUN to work on!

Everything is so small and light weight, some call them TOY cars...

I enjoyed working on mine - I was afraid at first, but EVERYTHING worked out fine!

I learned a Butt-Load about engines, bearings, fuel tanks, dashboards, injectors,
ECM's, Batteries - you name it!

My next BIG PROJECT may be the manual transmission and clutch in a while...

DoctorBill

First thing I'd do is replace the plugs AND wires. Easy to do, doesn't cost over $20 and may take care of the problem (and probably needs to be done anyway)

The grinding sound is constant. It starts when when I turn the engine on and continues throughout the whole time that I'm driving.

You could drain the oil and look for any metal particles. Also check the transmission oil for particles.

Check the fan belt and timing belt for anything rubbing.

You can also pull the lower plate from the bell housing, and check to see that all the bolts are tight. If yours is an automatic, there would be 6 bolts, that hold the torque converter to the fly wheel. If one backs out, then something could cause a problem.

I hope this helps.

My manual transmission is quite loud. In the cold, it has a coffee grinder sound.

Probably just age and the way it was made....like a motorcycle transmission.

Mine has about 170,000 miles on it now.

Getting rather long in the tooth - like me.

I'll drive it until it explodes !

At $3.20 per gallon and going up, you'd think more people would be demanding
1 Liter Geo Metros be made again - 50 mpg!

DoctorBill