rough idle

1999 CHRYSLER CONCORDE
162,000 MILES
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CARLOS1382
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1999chrysler concorde 3.2 v6 started to idle rough I changed spark plugs air filter and three ignition coils and its still the same so took it to a shop they said compression in #5was at 70 and and it was suppose to b at 100 then I took it to the dealer where I got it and they say its reading fine so my question is what is the compression suppose to b at and how low can it go before it is considered a bad cylinder also between 40-50mph car shakes horribly
Jun 14, 2011 at 8:53 PM
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RASMATAZ
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If the dealer says the compression is good on all cylinders something else is causing it could be one of the following below:

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

1.Defective spark plugs
2.Inadequate spark/coil,defective spark plug wire.
3.Lack of compression
4.False air leakage.
5.Faulty fuel injectors.
6.Insufficient fuel pressure.
7.Contaminated fuel.
8.EGR valve that is leaking.
9.Oxygen sensors.
10.Throttle position sensor.
11.Manifold absolute pressure sensor
12.Mass Airflow Sensor
13.Idle air control valve
Jun 14, 2011 at 9:05 PM
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CARLOS1382
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Would u know what the standard compression is supposed to b at
Jun 14, 2011 at 9:23 PM
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RASMATAZ
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Should be around 140-160psi and no more than 10psi differences from each cylinder
Jun 14, 2011 at 9:45 PM
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CARLOS1382
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So if cylinder five is at 117 should I b worried
Jun 14, 2011 at 9:52 PM
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RASMATAZ
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Give me all your compression readings and also you can do a cylinder leakage test to confirm where the excessivbe leak at-
Jun 14, 2011 at 10:34 PM
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CARLOS1382
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Ok I can get that info
Jun 14, 2011 at 11:24 PM
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CARLOS1382
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#1 120#2 117#3 120#4 118#5 117#6 120
Jun 15, 2011 at 9:32 PM
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RASMATAZ
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Is these dry or wet tests-Do a cylinder leakage test-sounds like timing chain or belt problem
Jun 16, 2011 at 12:29 PM