Odd idling issue

Quick background on the truck. It is an 05 F250. This is my brother's truck. He is stationed in South Korea for the next year so I am taking care of his truck and driving it on a regular basis so it doesnt sit for a year. He has the EGR removed, has done some work to the turbo and has a 4" downpipe. Has a tune as well. Since I have been driving the truck I have replaced his failing FICM module and upgraded his alternator to a 185amp.

The issue I am having is that the truck seems to have an odd idle issue that I have not noticed before, in warmer weather. Now that it is getting colder I am not sure if this is normal or not. I am still learning diesel engines. I will start it in the morning and it will be around the 700rpm range and after a few minutes I can hear it rev up and it is around the 1000-1100 rpm range. I can go otu and tap the gas pedal and it will drop back to 700 rpm range, but then it will go up after a few more minutes. Today I got in and hit the brake pedal and the rpm range dropped back down to 700rpm.

I havent noticed this before because it wasnt as cold. I am located in PA currently for work. I had to go out of town for a couple weeks and when I got back I started the truck up, it was a pretty cold morning and the truck started up fine but the voltage display he has in his truck was reading below 12 volts for about a minute. Now I have the same stumbling and bucking I had with the bad FICM module, so I fear that is out again as I am getting a P0611 code. I have that warrantied and can get it replaced and I will replace the batteries as well because the ccas were 700 and 750 and with the temp dropping I would like to have higher ccas to keep from frying the FICM. Could the FICM module going out be the cause of this odd idle??

Thanks
Andrew

The elavated idle is warm up high idle mode. Perfectly normal. The low voltage for a bit after start up I am sure was the glow plugs still on.

morepower02,

Awesome! Thank you for that information. I wanted to make sure I wasnt going to have a problem later on down the road.

Andrew

Does the stumbling and bucking issue come on while idling or when you take off driving?


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This happens while driving, usually during normal acceleration. Press harder on the pedal and it goes away. I have already replaced the FICM module once and it eliminated this. But the truck sat for 2 weeks and when I started it up for the first time it was 22 degrees out and I dont think the batteries had enough ccas and the module failed. It was working when I parked it and went out of town, then after that start up I noticed it again and when I pulled the codes I got the P0611 again.

Normally I have two EGR codes due to the EGR was d e l e t e d( sorry for the spaces but every time I type that word it is starred out like a cuss word). From the research I have done the EGR codes are due to the fact that even though the EGR is gone the PCM is still looking for it and this is the cause of the errors. I am going to get an SCT tuner for it so I can tell the PCM the EGR is gone.

Thanks
Andrew