99 running rough

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Mar 22, 2011 | 02:20 AM

fastnboulbous

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99 running rough

I have a 99 S Type which I have had since new. No major problems. Recently though it has started to idle rough once it has warmed up. It does not feel as though it will stall. Just this rather unpleasant feeling sitting at traffic lights.

It runs ok once you are moving and the revs are up but on idle it is quite rough.

Any thoughts?

Mar 22, 2011 | 05:56 AM

Thermo

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Joined: May 2008

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From: Great Mills, MD

Fast, try cleaning the throttlebody. Odds are, your throttlebody is sticking some and it is leading to your rough idle. The other thing to consider is when was the last time you changed the plugs. That can also play into this.

Mar 22, 2011 | 10:02 AM

H20boy

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From: Oak Ridge, TN

moved, and also revised title so it wasn't so vague, g-luck!

Mar 22, 2011 | 10:08 AM

bfsgross

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Joined: Nov 2009

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From: NY

X2 to Thermo's new plugs and clean throttle body. Plus: when was fuel/air filters replaced?

Mar 22, 2011 | 10:37 AM

JagV8

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From: Yorkshire, England

Don't clean throttle body yet. Post fuller car details instead

Mar 22, 2011 | 05:17 PM

jag79

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From: Orlando, Florida

...throw some lucas fuel cleaner in it, and cross your fingers.

Mar 23, 2011 | 08:29 AM

motorcarman

Joined: Dec 2009

Posts: 13,697

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From: Wise County,TX

Sounds like a failing on-plug ignition coil.

V8 or V6 does not matter as the on-plug coils are notorious for failing. I have BOXES of failed coils and most have green/yellow labels. The newer V8 coils have a BLACK label and seem to last longer. I haven't replaced a V6 coil in a while but I know some people get the replacements from parts suppliers for a FORD to save money.

V8 and V6 coils are different and won't interchange so get the correct ones.

bob gauff