Hesitation at low rpm's

[RMaguire]

I just bought an '05 2500 (3. 73 automatic) 2 weeks ago and have noticed some hesitation at low rpm's. As I'm driving through my neighborhood it feels as though the truck wants to shift but doesn't. I notice it most at about 1600 rpms. If I hold it steady the engine seems to hesitate and the trans will, sometimes, shift back and forth between 1st and 2nd as I drive at about 15-20 mph. Even when the trans does nothing it feels as though the power isn't steady.



To the best of my knowledge the truck is stock, minus the afe intake I installed (this all started prior to the intake).



I am at a loss and hope that someone has some input... help! #@$%!

 

[rbattelle]

I'm not sure I can be of any assistance. But on a new truck I'd recommend an immediate fuel filter change and check the transmission fluid level.

Ryan

 

[RMaguire]

I had similar thoughts... just haven't acted on them yet. The truck is an '05 but has 80k miles. I hope its something that simple!

 

[rbattelle]

To the best of my knowledge the truck is stock

Is stock, or was always stock? There's a subtle but important distinction there.



If the previous owner had a (several) fueling box(es) installed on the truck, and ran it hard, there are a number of other things that could cause a hesitation.



Things that come to mind include rail pressure relief valve, fuel control actuator, and injectors.



But like I said, start with the simple stuff first. Lots of diesel owners seem to be utterly clueless (not here, but in the real world), and maybe the last guy never changed the fuel filter.



Ryan

 

[PBrauer]

I just bought an '05 2500 (3. 73 automatic) 2 weeks ago and have noticed some hesitation at low rpm's. As I'm driving through my neighborhood it feels as though the truck wants to shift but doesn't. I notice it most at about 1600 rpms. If I hold it steady the engine seems to hesitate and the trans will, sometimes, shift back and forth between 1st and 2nd as I drive at about 15-20 mph. Even when the trans does nothing it feels as though the power isn't steady.



To the best of my knowledge the truck is stock, minus the afe intake I installed (this all started prior to the intake).



I am at a loss and hope that someone has some input... help! #@$%!

Governer regulator transducer and/or solenoid.



A sharp tech with a scan tool can watch the transducer with a scanner, drive it around and diagnose quickly. Transducer is highly suspect if it really does go back down to 1st gear. Sensor voltage is probably "hanging" at low pressure. Not a terribly expensive part or repair... good to do w/next trans. filter service.

 

[testraub]

Might also see about getting the transmission bands adjusted if it seems to be shifting kinda strange or at very high RPM's.

 

[Hoefler]

Governor regulator transducer and/or solenoid.



A sharp tech with a scan tool can watch the transducer with a scanner, drive it around and diagnose quickly. Transducer is highly suspect if it really does go back down to 1st gear. Sensor voltage is probably "hanging" at low pressure. Not a terribly expensive part or repair... good to do w/next trans. filter service.

There is a TSB out that addresses this.

 

[RMaguire]

I have yet to check the fuel filter, but will this weekend. When I changed the air filter it was completely black... I would not be surprised if the fuel filter has not been changed. I'll let you know what I find.



Should I look into some injector cleaning additives? ... which one?



Thanks for the help.

 

[JEstes]

When I changed the air filter it was completely black... I would not be surprised if the fuel filter has not been changed.

I would. I can tell a difference in my '03 after changing it at 10,000 miles so I can't believe it would make it to 80k and still run. It may have though! Did that seem to help how it ran?



Alot of people have reported having a black fuel filter too. Mine's pretty dark after 10k, and I'm pretty dang picky about where I get my fuel.



As far as the injector cleaning additives, that seems to be one of those things where you ask 10 different people, and get 13 different answers. I've used Power Service just to goof around, and that seemed to do a little bit. However, pulling my trailer and getting the EGT's up near 900-1000 and keeping them there seemed to be the best deal. As a daily driver, the egt's never get hot enough to really keep the engine clean. It's an industrial design, so it's intended to be really loaded up and worked hard.

 

[RMaguire]

I changed the fuel filter this morning and had my trans fluid and oil changed yesterday. The problem is still there, but does seem somewhat better. I've not driven a lot... we'll see how it acts after the weekend.



Thanks for the input!

 

[RMaguire]

"Governer regulator transducer and/or solenoid. "



Anyone have part numbers for these?

 

[PBrauer]

"Governer regulator transducer and/or solenoid. "



Anyone have part numbers for these?

Most dealers keep the solenoid and transducer in stock. There are about four parts that most experienced trans techs will "shotgun" before spending too much time troubleshooting. These are the first two. Speed sensor and the Overdrive/TC solenoid are two more. The speed sensor is cheap ($15 and mounted outside) and the OD transducer is semi-easy to replace once the pan is off. I'd replace the first two and have the bands adjusted while they're in there (one is inside the pan and you need a low in-lb torque wrench to DIY). If anyone asks, the thermistor is built into the transducer so don't "hunt" for a separate part.



Better nomenclature:

Governer Pressure Solenoid Valve (Solenoid)

Governer Pressure Sensor (Transducer w/Thermistor)

(Transmission or Output) Speed Sensor

Overdrive/Converter Clutch Solenoid (ONE part w/two solenoids)



I actually have all of these parts (for '06 48RE) ready to go in myself but they're buried right now. I'll try to get pn's into the thread but a dealer should find them easily... don't think you can get them anywhere else anyway. The OD/CC solenoid probably isn't your problem unless that sensation of "1st gear" you're feeling is actually TC lockup related... . not likely but possible, I guess. It's also the most expensive part I think.



It wouldn't hurt to verify operation of the Tranmission Range Sensor, since it's easy, but in your case I doubt it's the problem. Several resistance checks with a DVM while you move the shift lever... nothing fancy and the plug is easy to get to. If you intentionally "jiggle" the shift lever while your at it you can detect a problem with the cable/adjustment.

 

[JimB1]

Bio-diesel is excellent fuel system cleaner and lubrication. National Biodiesel Board - www.biodiesel.org - www.nbb.org is website with national map of retailers. Change fuel filter again after couple tanks.