I have a 88 F-150 4 X 4 with a 300 EFI engine. I have developed an engine miss at an idle. It was erractic at first, but now does it all of the time. I have, in the mean time had the truck at the Ford dealership, they installed a new injector, O2 Sensor, plugs and new wire on the #1 cylinder and adjusted the idle. I have also installed a new TPS. I have removed the plug wire on number one cylinder while running but does not seem to change the miss. I have performed a compression check all was in spec. At times the engine almost is at the piont of dying, but at other times it will run fairly smooth, but still has that annoying miss. Does anyone have an idea what is going on, since the Ford shop can't seem to find it?

Thanks.

 

Can you hear any noise in the engine? Maybe a ticking sound coming from the valve cover or the lifter area? Try the old screwdrive listening device thingy method (get a long driver and hold it to the block and listen to the other end). See if you can hear any ticking that way. You and the dealer have gone over the obvius so it's time to look a little deeper. I am thinking that you might have a lifter that is bleeding down at low rpm's. A tick in the engine would confrim this but sometimes a bad lifter doesnt always make a rattle.