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rough idle; Idles rough, runs fine
Topic Started: Oct 18 2011, 06:38 AM (1,841 Views)
brikony
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I have a 97 Geo Metro 4 cylinder with 308,000+ miles on it. Recently it started idling rough. So I changed the plugs and plug wires. No plugs were fouled. It ran the same. Then I changed the distributer cap and rotor. Still idled rough. Next I took off the EGR valve and cleaned it. It did look plugged but it still idles rough. Maybe worse. When the car is under power it seems to run fine and has full power. This has been a great car but I'm at a loss. Where do I look next?
Edited by brikony, Oct 18 2011, 09:39 AM.
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captain1.0


Next you look at getting somone or do it yourself a engine compression test. Welcome to the forum.
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brikony
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O.K. I've done the compression test. Here's the results (and they don't look good to me but I'm listening). Cylinder 1 -- 155. Cylinder 2 -- 150. Cylinder 3 -- 140. Cylinder 4 -- 105. Now what do I do?

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brikony
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O.K. I've done a little more. I've pulled the plug wires off one at a time and plug wires 1 and 2 make the car run even rougher when pulled off. Plug wire 4 might make a little difference. But plug wire 3 doesn't make any difference at all. Where should I start looking?
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MR Bill
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Looks like number is dead, start there.
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captain1.0


Pull plugs and clean and inspect. Take a spare spark plug or a screwdriver and carefully ground the number 3 plug wire to ground somewhere and see if you are getting a spark to number 3 plug. Those low compression numbers do not help your idle at all. For further engine testing you might want to hook up a vaccum gauge and see what you get. Are you getting a check engine light?

Check out scenario 4, 5 and 6 here,

http://www.secondchancegarage.com/public/186.cfm
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brikony
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I had a check engine light for a while but it went out. If this kind of idling doesn't cause a check engine light, I don't know what will. Tomorrow I'll buy a vacuum tester and see what I can figure out. The web-site you led me to makes me wonder what I can learn.
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captain1.0


At 300000 miles it has to be worn out, if noone has done any major engine work to it.
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Woodie
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brikony
Oct 18 2011, 09:05 AM
O.K. I've done the compression test. Here's the results (and they don't look good to me but I'm listening). Cylinder 1 -- 155. Cylinder 2 -- 150. Cylinder 3 -- 140. Cylinder 4 -- 105. Now what do I do?

Pat it on the head with a "job well done" and rebuild it, it's finished. I'm surprised it still has that much compression at that mileage.
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brikony
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The check engine light is on. How do I figure out what that means?
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idmetro
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Head down to your local big box auto supply place and have the codes read with their scanner (this is assuming you don't have your own) Make note of the codes (some places will actually give you a print out) check here http://geometroforum.com/topic/638390/1/#new to see what you've got.
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Norby
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brikony
Oct 18 2011, 09:55 AM
O.K. I've done a little more. I've pulled the plug wires off one at a time and plug wires 1 and 2 make the car run even rougher when pulled off. Plug wire 4 might make a little difference. But plug wire 3 doesn't make any difference at all. Where should I start looking?
Reinstall the plug wires and instead disconnect the 3rd cylinder fuel injector. Does it still not make much difference in how it idles?
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bogs
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Duct tape heals all wounds

You can get the codes read at Advanced Auto or Autozone (or any number of parts places) for free, we have a codes section here for the results or they might advise you there ... take their advice with a grain of salt.

Check engine codes -> http://geometroforum.com/topic/638390/1/
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