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4.5 misfiring under load

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Has anybody ever had the pleasure of trying to diagnose a misfire under load? And if so, what did you do to figure out the suspect cylinder? /forums/images/%%GRAEMLIN_URL%%/shrug.gif

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i dont work on lcf trucks but i do work on a ton of 6.0's. i will assume that it is pretty much the same. i have had a few 6 liters that have had injectors drop only under high load and high rpm with no codes. i have had good success diagnosing these actually starting the engine cold and watching which cylinders drop off when cold. I replace those injectors that are not contributing correctly and have had good success with this.

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Alex I ran into this with a VT-365 no too long ago and it requires the use of the injector disable feature in Master Diagnostics. If you don't have the MD Truck software and comm cable you are dead in the water. I have had the opportunity to play with this a bit and it gives you a real appreciation for the Ford electronics and the IDS capabilities...

 

See this topic as it might have something for you: http://www.forddoctorsdts.com/forums/ubbthreads.php?ubb=showflat&Number=13439&page=1#Post13439

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No kidding Keith. I can't believe how much more user friendly IDS is than MD Truck. The injector disable test isn't giving me anything to go on, and will not run under the conditions my misfire is present. I called the MD hotline, and was asked if I had a "suspect" cylinder. If I had a "suspect" cylinder, to replace all three cylinders on that bank. If the misfire was still present, swap the three injectors out with the three on the other bank... if it's still evident, replace the other three. Sheesh... ya think they could have added a phucking power balance test to that software!

 

And, on top of that... the "autorun" portion of injector disable test and relative compression will not highlight in the menu, so I can't select them... arrrrrrrrrgh! /forums/images/%%GRAEMLIN_URL%%/smhair.gif

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