Greetings - I have a 98 F150 with a 4.6 V8 and 135k miles. I recently changed the DPFE sensor (ERG insufficient flow) and the downstream O2 sensor to address some engine codes and seemed to clear OK. Previous to doing this, when I started cold and put into gear, the engine ran very rough and could smell rich exhaust, but after engine would warm up it would run OK. After reparis to DPFE and O2, this is still happening and I am now getting error codes for #4 and #7 cylinder misfires and systems too lean on Banks 1&2. Now also when I am accelerating the engine seems to miss and I get a jerking feeling from the engine and loss of power. In addition to the check engine light being on from the Codes listed above, at varied times the check engine light starts blinking (is it saying, please put me out of my misery?). I have been watching for a couple weeks and the error codes and engine roughness have been consistant, but seems to be getting slowly worse. Any help would be appreciated.

 

check the plugs and wires on the # 4 and 7 cylinder and check for water inside the plug slot. If you have not changed the plugs in a while change them both wires and plugs. check for vaccum leaks on the top of the engine, easily done buy sparying a carb cleaner around the engine where ever you spray and the idle increases is a sourse of a vaccum leak replace the pcv valve and check the hose for leaks. remove the throttle boddy and check the egr portal holes to see if they are clogged from the inside of the manifold if clogged clean out with a drill or something that can get in there after all that you may have to change both upstream O2 sensors, for the lean on banks one and two. The problem you having is comon with that truck there are many threads covering your problem. Good luck

Lance

 

Thanks Lance - I finally got to changing the plugs and wires this weekend and the truck is running just like new again.