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3406a misfire

324 Views 5 Replies 3 Participants Last post by  sname5978
I'm having problems with a 400 hp 3406a DI engine. It runs fine when engine is cool but at about 150 degrees it starts to misfire at idle. By the time it reaches 180 degrees, it misfires at 1500 rpm. It only misfires at a very narrow range of rpm. Speed up or slow down a few rpm and it smooths out. It's not like a miss on one cylinder, but like all cylinders are short of fuel.

Under load it runs fine, good power 30 pounds of boost. The only time it misfires is at no or minimum load. Fuel pressure is steady at 30 pounds. Valves have been lashed, I had the nozzles tested, checked the timing, no air in bypass fuel, plungers appear to have been replaced. I purchased this as a used engine and put it in my 1980 W900.
It has run like this since installation probably 400 miles ago. Any suggestions would be appreciated.
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Don't use open flames. Even up in Alaska in the good ol days they used a pan of hot coals not a camp fire like some people claim, clearly that'd melt anything rubber. Best option is some sort of propane heater or engine block heater
momix activate
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