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Old 01-08-2007, 12:45 PM   #1
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Default Rough Idle

I am having a little bit of a rough idle. It is nothing real bad or serious, just not "smooth".

The plugs and wires have less than 5k on them, I did the ignition swap and got all my coils pretty close to the same resistance values, new air filter and pcv valve same time as plugs.

I have also had the fuel pump replaced due to failure around 2k ago. Fuel filter replaced when pump changed. I also replaced the MAF and adjusted the TPS.

What are some other things to look at? It is not an issue that is causing problems, just a concern.

P.*. the MAF was only changed due to it getting broke when cleaning the TB.
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Old 01-08-2007, 01:35 PM   #2
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Old vacuum lines rotting out and leaking will frequently cause a rough idle.

Since you've done plugs, wires, cleaned TB etc.. that would be the first area to check.
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Old 01-08-2007, 06:40 PM   #3
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You have to explain a bit on rough idle. If by rough that it shakes the car, and smooths out with higher revs, that could be your balancer. If the tach hunts for idle, that'* IAC. If it doesn't sound smooth at the exhaust, that'* uneven compression/ turbulent airflow [carbon caused]. You've got the basics checked out... but you do have low mileage [low chance of low compression, along with carbon buildup]... could be injector caused. Leaky injector by chance? Good O2?

Again, vacuum lines can be the cause as well. Vacuum gauge it, and see. 18inlbs right on the dot for me. So it should be exactly the same for you...
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Old 01-08-2007, 07:37 PM   #4
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didn't notice any bad vacuum lines, and I have never done the O2 sensor. It does look to be the original.

It is not a real rough idle that shakes the car. It is only noticed when I open the hood and listen to it idle, when engine is slightly accelerated it isn't noticed.
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Old 01-09-2007, 10:36 AM   #5
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Yeah, I have the same exact thing. Don't worry about it, just one of those things about owning an older car. Listen to the exhaust when it is idling [hot], doesn't it sound sick? At idle, my tach is smooth, and under the hood if you really really listen you can kinda hear a bit of an off idle... but at the exhaust it makes it sounds like it has a blown head gasket and no compression on 2 cylinders.

You may want to also check out the PCV system. That seems to make a big difference when that seals up perfect.
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