5.7 Hemi 545rfe OD Rpm Pulsing

[ckruzer]

2010 Ram 1500 Hemi 5.7 545rfe, No loads

Specifically and only in the mph range of 45 to 55mph, with cruise pedal pressure, and in OD with rpms being in the 1200 - 1490 range, the rpm needle and engine (noise) will pulse rapidly 50 rpm (think tach needle width) non stop until you either release gas, or get rpms up. Does not happen in any gear but OD, does not happen in OD when above 2,000 rpm (above 55 mph).

I can get it to happen nearly on command when the road and traffic enable me to perform a "lulling" OD cruise speed in that mph/rpm range.

MDS is turned off

Any thoughts on cause?

 

[crackerjack1957]

Miles on spark plugs?........this normally happens with the older copper plugs with large gap under low rpm load in OD.
May not be the problem but easiest to check if not sure of mileage on plug.

 

[ckruzer]

Good idea. Im gunna be tackling the exhaust manifold bolts and plugs in a few weeks. Ill report back if it changes it.