I've been searching but haven't found an answer. I have an 04 QCLB 3500 with the 48RE, 245,000 miles. Ony mod now is the Banks exhaust, there was a tuner on it before I bought it, but I don't know what it was. Appears to have a newer turbo, and has had the head off at some point in the last year or so.
My problem is that the truck occasionally surges, the first time I noticed it after about 3 hours on the interstate running 70 or so. It acted like I was power braking. Kind of akward when you're sitting at a stoplight next to a station wagon. It would surge 300-500 RPM. I changed the fuel filter and started running BG fuel conditioner. The surging is not nearly as bad now, but it occurs most often when the tank is under 1/4. It surges just a little(100 RPM) while driving.
It doesn't smoke, well, there's always a barely noticable black puff when I take off, but that's it. Starts easily, never more than 2 seconds cranking, usually less. I know gauges would help, but my wife lost her job last month so my toy budget is gone. Anyone have any ideas? I'm stumped.

 

when you say surging, is that the RPM are going up all by it's self?

 

Yup. I can pull up to a stop sign, foot on the brake, and the thing will act like I'm tapping the throttle. I did forget to mention I put on a new APPS from Timbo. I also had the fuel system cleaned(hooked up to some machine) I'll get the details of what all it does and post a little later. I can be idling down the road in town and the RPMs will jump 100-200 on it's own. It makes me look like I'm trying to impress someone. Not impressive when yer 43.

 

Two common causes for this is a rail pressure sensor on its way out or the FCA sticking.

 

soulzoo is right but I'm leaning more towards the FCA acting up since mine was doing same thing......except WWAAAYYYYYY worse!!! Mine would actually drop in rpm's to about 350 or so, rattle like an old 24v , and then race up to about 2k and then come back down........several times in a row......but only at idle. Other than that, it did have a slight surge while driving down the highway.

If you have a local Cummins shop nearby they should be able to hook you up for a $100 or so. DO NOT BUY THAT THING FROM THE DEALERSHIP!!!!!!!!

 

part # is 4932457
$92 from Freightliner

 

Thanks guys, I'll look into it.

 

Dealer wants over $200.

 

FYI
I buy a lot of parts at Freightliner for the company i work at, my price may be 10% over cost.

 

I would also recommend changing the FCA, especially if it's the original. Heck, I had to change mine at 65k miles because it was acting up.

Might as well install a fresh COV (Cascade Overflow Valve) also. Easy to change and only $40.

MikeyB

 

I think that's the route I'm going to take. Thanks guys.

 

Fixed it last month, but forgot to post the results. I wound up replacing the FCA and the cascade overflow valve. Took about 15 minutes, spent more time just looking things over than working.
Took care of all my problems, truck runs great. Combine that with the BG fuel injector cleaning I had done(posted elsewhere about that)I'm pulling down 19.5 mpg hand calculated to and from work. That's 75 miles each way with a 20 mile run at 76 mph and the rest at 60. Pretty respectable I'd say.

 

Good to hear that!

MikeyB

 

Did you replace with OE parts? Where did you buy from?

 

I wound up needing the parts in a hurry. Spent a few bucks more and got them from Geno's.