This is my first thread on this forum but I have been getting very good info for years.

I have a 2007 Dodge Ram 1500 with the 5.7L Hemi with 115K miles. Nothing has been modified on the truck except I put a drop in K&N air filter and magna flow exhaust.

When I am traveling at just about any speed including stopped sometimes my RPM's bounce and have noticed it more with my exhaust. I set my cruise control all the time on my way to work at about 70MPH and notice my RPM's bounce from 1900-2100 constantly. It does it at lower speeds but that is the speed I notice the most. I have tried turning off my A/C and taking my truck out of over drive but it still does it. I recently had all 16 plugs and boots changed out and no improvements with the RPM's. There isnt a check ingine light or any codes on. If you have any info on what this could be please let me know. Thanks Dodge Forum

 

Does it also fluctuate at idle or is the needle rock steady???

 

it fluctuates at idle also.

 

My idle its a rock steady 650... I grounded the TB and that is why.
The MDS kicking in and out at 70 mph is why your rpms bounce around a little.
My truck fluctuates about 100 rpm with 3.92 gears at 70-75 I think this is normal...though the slight drone makes it seem worse.

 

Yep, ground your throttle body...

 

I will try this for sure. I dont understand it 100% but it is free and it cant hurt anything. I will post tomorrow if I see any change. Thanks everyone!!!

 

Well its a little crazy to me but I grounded my TB and put in a new K&N Air Filter and seems to have worked for now. I still have to go to work tonight so the 37 mile trip should tell for sure. I forgot to take pictures but it took about 30 minutes to do this mod because my tools seem to get up and walk away sometimes so it is a treasure hunt to find them. I connected the 10G wire to the lower right bolt on the TB and the other end to the ground coming off of the battery that is connected to the body of the truck. Thanks again for the comments and I will post again if I dont have any problems on the way to work.

 

Well on my way to work my truck does seem to be responding better since I grounded the TB and installed the new K&N filter. The RPM's are still bouncing at all speeds though. It sounded a little too go to be true but it was worth the try.

Is it possible that my torque converter could be going out or one of my ignition coils could be getting weak?

I havent changed my fuel filter or cleaned my injector yet but I am trying to rule out the obvious first.

 

Has this always happened, or have you just now noticed it?

 

Well unfoutnately you cant change fuel filter without changing the pump.


When your trucks RPMs bounce does it sond like the trucks motor is bouncing with the RPMs or the RPMs bounce by them selves with no motor noise, if so id start looking electrical