2007 5.7 HEMI – Bogging at Cruising Speed 1500-1800rpm (Possible MDS Issue?)

[Smeeks]

Hey everyone,


I’m looking for some help or insight on an issue I’ve been dealing with on my 2007 Dodge Ram 1500 with the 5.7 HEMI. I recently did a bit of work to resolve a misfire issue and some other check engine codes I was getting (misfire, O2 sensors, camshaft, and crankshaft sensors). Here’s what’s been replaced recently:

• Spark plugs (iridium, not copper)
• All coil packs (NGK)
• Camshaft and crankshaft sensors.
• O2 sensors
• MAP sensor
• Starter (this was just going bad so I replaced it)

After all this work, the truck runs and accelerates fine. No more misfires, and no active codes. However, I’m noticing a strange issue when I reach cruising speed—typically between 45 to 60 mph, and around 1500–1800 RPMs. It feels like the truck is bogging down slightly—the exhaust note changes—but it’s not actually losing speed or fluctuating RPMs.

I suspect it could be the MDS system kicking in and maybe not running quite right. But I’m not sure. I’m a novice when it comes to the 5.7 HEMI, so I wanted to ask the community:

Has anyone else experienced this sort of bogging when at cruising speed?

Could this be related to running iridium plugs instead of the OEM copper ones?

Any ideas on what to check next?

The truck starts fine, pulls strong, and doesn’t throw any new codes.


Appreciate any guidance you all can give. Thanks in advance!

 

[jws123]

Yes that sounds like the MDS kicking in It will bog down when it does at crusing speed. Just tune it out it does not work well to begin with and gets worse with age it has no benefit.