7.3 engine misses till normal temp in cold weather

[George K]

My 2002 F350, 7.3 misses when the weather is very cold, below 35 degrees, until it warms completely up. But it only misses in a crusing mode. When I step on it, it straightens out and pulls very well until I let off on the throttle and it starts to flutter again. When the engine is at normal temp it runs very smoothly in all throttle positions. Anyone have this problem and solved it? I hate to take it in to the Ford Garage and have them change every sensor till they fine the right one. I can do that myself if I have to. Any help would be greatly appreciated.

[mschn99]

its probably an injector or two dropping out cold. Without looking at a few readings on a high dollar scan tool though..i cant say for sure...

[George K]

The engine missing or fluttering that I had until the engine was totally warm, I cured today after looking at the truck engine in our near subzero Wisconsin morning. Because of the way the truck acted by running smooth when I was on the throttle made me think it was some sensor cutting fuel delivery, thinking the engine was warm, when it was not. Well I don't think it was that but looking at the turbo I can see a valve assembly under the two sections in the middle. Probably holds back on air until it warms up. I could not see the rear of it but I disconected the connection going in to it to see if that had anything to do with it. I took it out for a drive and like a miracle the engine runs perfect. I think it does take a little longer to warm up than it did, but what a relief to have it run good. Apparently there is something wrong in that valve or what activates it but it must fail/safe in a open mode because the truck has all the power it should. Anyone have any ideas of what I should do now. I don't think this valve is needed because a friend of mine has a F550 with a 7.3 and that valve is not in it. It might just be another gadget to make the truck more comfortable for the folks who buy these big trucks to go to the grocery store. Thanks for any help guys.

[djsdiesel]

George
That is the Exhaust Back Pressure Valve. It is there to aid in cold weather warm up. Most people unhook this or take it completly out. If you are going to unhook it, unplug the wires. If you just unhook the rod you will get an oil leak.

[George K]

Actually thats what I did, I couldn't even get to see the linkage on the back side in the 10 degree weather. It does take longer to heat up, you're right. Heading to Arizona after the first and it will be fine then: Thanks again!