roccon31
Bronze Member
(Or you didn't use them properly. Cycle the key switch 2-3 times waiting for the glow light to go out before doing it again.)
john, please do not take offense to this, i am not singling you out.
it is a common misconception that you have to cycle the glow plugs on the powerstrokes, like you did on a poorly functioning older style system. YOU DO NOT have to cycle them several times. all this does is prematurely burn out the plugs!!!! the older 6.9 and 7.3 engines used a sensor mounted on the back of the block, determining the glow times. they were semi-reliable, as long as the plugs were all good. one plug went out, and the cycle times were affected. this is when you had to cycle them to get the truck to start. most folks dont realize they have a plug or two out until the truck no longer starts, then they realize they have 5 or more out.
the powerstroke computer is programmed so that after the dash light goes out, the plugs remain on for a certain amount of time, up to about 2 minutes with the engine off. once you crank and start the engine, the plugs will cycle on and off to reduce smoke by increasing combustion chamber temperature. this is decided by the oxygen sensor among other things (knock, etc)
the light stays on for a predetermined amount of time, depending upon engine temp and ambient air temp, all decided by the computer and glow controller.
i recently had a friend with a 99 7.3 f250 call me up complaining about his truck that it would not start below 40 degrees. it started fine above 40, no problem. first thing i did was check the plugs. ALL 8 WERE OUT!!!! i couldnt beleive it, i checked the relay, the valve cover gaskets (the wires go through the gasket under the valve cover, they do fail) i yanked the valve covers, threw 8 plugs in it and sent him home. the next week it was 14 degreesin the AM, and the truck fired right up without a block heater. moral of the story is- CHECK YOUR GLOW PLUGS!!! pm me if you need to know how. its easy.