Engine Missfire??

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Apr 19, 2005 | 02:54 PM

merlins'92f250d

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Joined: Apr 2004

Posts: 140

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From: Marinette, WI

Engine Missfire??

My '93 f250 7.3 has a miss I can not figure out....been looking for a while but missing something and would like some help from you guys!

Truck starts good runs great( had to change tranny last week but that is minor)
when I start it up it has a miss untill warms up (cold ignition temp I figure) then after it warms up it will start missing again as I go down the road usally around 2200 rpm once it upshifts the miss is gone, I ran it 200mi at 75mph and no miss, just while it is shifting up
with the miss I get a puff of white smoke then it shifts and smothes right out!
any ideas??
thanks!

Apr 20, 2005 | 05:45 AM

bilder12

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Joined: Sep 2002

Posts: 1,897

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From: Northeastern Pa - USA

The miss on start up could be due to a bad glow plug not helping a cylinder fire up while cold. Should show up as white smoke at the exhaust and rich fuel odor. The miss after warm up cold be anything from a weak/broken injector to a failing injection pump. Try plugging in the block heater in the morning for a few hours and see if that helps the first problem. Give the fuel a rich dose of power service or the like to see if you can clean up a bad injector. To test for the bad injector, with the engine at idle, break loose the fuel line at the top of the injector and see if one of the cylinders does not make a difference ... that would be the bad one. You may have to loosen the lines before you start the engine then snug them back. This will keep you from performing lots of work around moving parts. Hope this helps.