Intermittent Miss

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- - - - - -- - - - - - - - - - - - -- - - - How many miles on plugs?

Seems to me that CEL doesnt lite on occasional miss, if it's a plug problem.

Brand of plug? Possibility it's Bosch.

it doesn't do it all the time and there is no check engine fault code. I thought the computer would detect a misfire and tell you which cylinder. Any ideas where to look to find the problem? Thanks

it doesn't do it all the time and there is no check engine fault code. I thought the computer would detect a misfire and tell you which cylinder. Any ideas where to look to find the problem? Thanks

I would start by cleaning or replacing the IAC. Your problem may be as simple as low idle speed especially if it does not always start the first time when cold.

The EEC system will detect a "dead miss" within a few (200?)revs, a random misfire within , IIRC, 400 revs. If the stumble is multiple cylinders, such as caused by a vacuum leak, it won't trigger a misfire code. It should catch a rich or lean condition though. You need to have someone monitor the PIDs (signals to and from the sensors) to help determine the problem. You don't mention mileage, but if it's over about

65K start thinking about a tune up (plugs, wires, filters). God, I can remember when plugs were needed for sure at ~15k and wires every 30k, (and points about every time you passed the city limits, it seemed).

Hey Backyard, I'll second your motion about Bosch plugs. ;) They drive later model Fords crazy. I just pulled a set out of an 01 3.0 Vulcan Taurus today. The owner put the Bosch plugs in about a month ago. All was fine then the car developed a stumble on light acceleration (tip in), no matter what speed. A set of Autolite Coppers, problem solved!!

99 Taurus has a intermittent miss noticeable while idling in gear. As I said, it doesn't do it all the time and there is no check engine fault code. I thought the computer would detect a misfire and tell you which cylinder. Any ideas where to look to find the problem? Thanks