Rough Idle problem finally fixed!

[slimjim]

My truck has idled rough for the past 8 months. When I say rough, it never sounded like it was missing or anything like that, but the RPMs would fluctuate slightly and it would just feel like a vibration that would come and go. I searched all the forums over and over, and put in a new CPS, ICP, cleaned my EBP tube and sensor, cleaned the FPR screen, new fuel filter, air filter...etc. You name it, I did it.

I'm sure it's out there, but I never found anyone talking about the EBP sensor causing a rough idle. Today I unplugged it and took it for a test drive. Not a single hiccup. Couldn't even feel the motor running.

I just wanted to post this so that maybe other people will find it and be able to fix the annoying vibration at idle issue. All the other things that I replaced did help in other areas such as acceleration and fuel mileage, though, and all of them can cause a rough idle, so if the ebp sensor doesn't fix your problem try doing those.

[White95f250]

Good to know, i'm about to tackle a little "miss" and rough idle here soon.

[mamatried01]

Mines running idleing with a miss too. Where's the EBP sensor?
I need to replace my fuelpump I think, there is fuel in the valley on top of the motor. I put on the 6637 filter, new fuel filter and opened up my exhaust, no cat or muffler. Still idles rough but when you stab the throttle it smooths out and runs strong. Shop that rebuild my tranny said injectors were good that it was probably something internal with one or more of the cylinders being bad.
Has 336k miles on it.

[psdstrkD95]

Same problem ebp huh I should try mine has been kicking on after it has been warm which is really goofy. Can I just unplug the turbo one or is it actually the signal to the pcm that's screwing the idle up? And the rough idle is also the "miss" that I hear on the driver side "ish" its kinda hard to tell over the diesel noise.

[Patrick Feeley]

The Exhaust Back Pressure (EBP) sensor is near the High Pressure Oil Pump (HPOP) Reservoir on the top front of the motor (the EBP has a tube from passenger side exhaust manifold going to it). This is the one you want to unplug to see if it runs differently). Cheers!

[MT_Truck]

Here's a great picture tutorial on how to fix it

[BigFuel]

That is a decent write-up but the EBP on the OBS is on the other side of the HPOP sump cover. Works the same way but just a little different position than the SDs in the pictures.