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The power of built in scan tool functions
Posted to Technical Discussion Forum on 6/27/2013 47 Replies

I had a 2005 Ford Taurus come my way requiring a drivability diagnosis. It had a dead misfire, and even taking the misfire into account it was idling very poorly. I checked Continuous Mode DTCs, the P0171 Freeze Frame, and PCM KOEO codes . There are many ways to handle this vehicle, but I'll share what I did with my IDS.

First, I checked power balance. Next, I checked relative compression. I then checked relative injector flow. I was already in the Fuel System tests, and I did have a P0171 so I thought I'd just check running fuel pressure and fuel pressure leak down really quickly. I already knew where I was going for the misfire, but before I got out of the driver seat I thought I'd just peek at some scan data.

At this point I already know I have an ignition system related misfire. Not hard to guess, certainly not hard to determine through other methods. I was able to quickly eliminate/confirm a variety of things and narrow my testing down to the most pertinent area.

I put my capacitance pickup on cylinder #3's ignition cable and checked Power and Waste secondary waveforms. The spark is not occurring in the combustion chamber. I put a spark tester set to 20kv on the end of the ignition cable, and a low amp probe around the coil common power wire. No spark at the spark tester.

100k on the odometer, original plugs, orginal ignition cables, and a defective coil. A set of plugs and cables, with a new coil and the misfire was corrected. A KAM Reset, fuel trims back to normal, misfire gone, and away goes the vehicle: fixed.

This was not a complicated failure, nor a complicated diagnosis. This vehicle certainly could have been diagnosed a number of ways utilizing a wide variety of tools and/or methods. Still, the power of the built in test functions of the Ford IDS for this vehicle made it a no risk, low effort, high comfort diagnosis.

Shannon from California

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car Vehicle Data

2005 Ford Taurus SE 3.0L

Engine3.0 L
Trans4-speed Automatic (Electronic)