I have a late 2004 f-350 6.0l powerstroke I bought the truck about 8 months ago with 127000 miles on it. it now has 140000 miles on it. i use it to tow the bobcat around and to get loads of materials for the guys at work (construction). however lately ive been using to go back and forth from school mostly. i did a oil change and fuel filter change about 500 miles ago and started using rev ex fuel and oil additive. at 135000 i put in a new bulletproof egr cooler and a stock oil cooler.

before i put in the new egr cooler i was having problems with the idel. i would come up to a stop light or be sitting in traffic and it would droop to about 500 rpm then shoot up to about 750 rpm. it only did this when the truck was warmed up and it would do it somewhat speradicly. i put the new egr and oil cooler in and it stoped for about 5000 miles but now it is doing it again. my oil and coolant temps are at about 185 F warmed up and it is not throwing codes (scanguage 2). any ideas what it might be? any help is much appreciated thanks

 

Are there any codes?

 

nope no codes. ive brought it to two different mechanics and nobody can figure out what it is

 

Make sure the camshaft and crankshaft position sensor are plugged in all the way and don't have dirty or corroded connections. Also check the wiring going to them to make sure they are not shorting out. Does it idle like this all the time or is it a sporadic thing?

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Does it still have EGR valve in it if they start getting sticky they will idle very erratic also just because your running Rev X doesn't mean you don't have a couple injectors sticking my 6.0s would start sticking injectors rev x or archoil would clear up for a bit but then take a dump later and never throw a code it also would never throw a code if the egr valve started to stick so I just deleted it

 

@george.maness86
thanks I will check those and it is pretty sporadic if im doing city driving but if I am drivng for a hour or so towing a trailer it is pretty consistent.

@FRIDAY88
ya I still have the EGR valve in it but i think im going to try cleaning it. and also i don't think its injectors because it was doing it then it stopped for 5000 miles and now its doing it again. i would think if it is injectors that it would be fairly consistent i could be wrong tho im pretty new to the whole diesel enginge ive always just had gas engines.

 

The 6.0 injectors are a mysterious thing egr valve will defiantly cause a erratic idle

 

ok ill make sure to look at the egr valve and thanks for the help

 

Check all wiring make sure there's no spots rubbed through on the engine harness anywhere expecially up by the FICM module to just to make sure

 

Also when was the last time you changed your Oil? I've had tons of 6.0s some that would run 7000 miles without issues some that I couldn't go more that 5000 miles on synthetic oil before it would start running rough these 6.0s like to break down oil and I'm sure you know that the Fuel Injectors are fired off the oil so you need good healthy oil in it at all times when it starts breaking down it will start missing and running very erratic