P0308 on Dodge

Some 2015-2021 Dodge Challenger 5.7L and 6.4L engines can develop a persistent engine-speed-related tick, rough idle, loss of power, or misfire from hydraulic roller-lifter, roller, or cam-lobe wear. A tick alone does not prove internal wear: exhaust-manifold leakage, injector noise, oil-pressure concerns, and other causes must be ruled out. MDS fitment is transmission-specific, not engine-name-wide: automatic 5.7L and 6.4L applications use cylinder deactivation, while six-speed manual applications are non-MDS. Cam and lifter wear is not limited to MDS hardware.

The 3.6L Pentastar V6 engine can develop a ticking noise from worn rocker arms. Unlike the HEMI MDS tick, this is caused by the roller follower rocker arms wearing out prematurely. The issue typically appears between 50,000-100,000 miles and is more common on 2011-2013 engines but can occur on later models.

A P0300 "random/multiple cylinder misfire" code with a rough, shaking idle is one of the most common drivability complaints on the Dodge Challenger, and on a high-mileage or maintenance-overdue car it is most often caused by worn spark plugs and/or weak ignition coils rather than an internal engine fault. The 5.7L and 6.4L HEMI V8s are especially prone because they run two spark plugs per cylinder (16 total), so worn plugs are a frequent misfire source; the 3.6L Pentastar V6 also commonly throws misfires from failing coil-on-plug units. Because P0300 is the "random/multiple" code (versus cylinder-specific P0301–P0308), it points to a condition affecting several cylinders at once — typically a full set of tired plugs, or coils that break down intermittently under load/heat. Owners notice it most at idle and during light acceleration. Critical: if the check engine light is FLASHING, the misfire is severe enough to dump raw fuel into the exhaust, which can quickly overheat and destroy the catalytic converter(s) — turning a routine tune-up into a far more expensive repair. Note: the 2011–2013 3.6L V6 also had a documented left-cylinder-head defect (Chrysler warranty extension X56), and 2014+ Pentastars can suffer rocker-arm needle-bearing wear; these can present similar misfire codes and should be ruled out if new plugs and coils don't resolve the P0300.

The production valve springs on the 6.4L 392 HEMI can crack or fracture. A weakened spring can cause a persistent single-cylinder misfire that remains after plug, coil, or injector swaps; a complete fracture can let the valve contact the piston and cause major cylinder-head or engine damage. High-RPM and modified/cammed use changes valvetrain load, but the correct replacement spring must be selected from the camshaft's lift and required installed/open pressures rather than from boost alone.

HEMI engines with Multi-Displacement System (MDS) can develop a ticking noise from the MDS lifters. This tick is most noticeable at idle and during light acceleration. While often not causing immediate damage, it can indicate lifter wear that may eventually require attention.

The 3.6L Pentastar V6 can develop a ticking noise often related to the rocker arms or hydraulic lifters. This is common on engines with higher mileage or irregular oil change intervals. Some early Pentastar engines had rocker arm design issues that were later updated.

The 3.9L and 5.2L Magnum engines use a two-piece intake manifold: a cast-aluminum upper and a stamped-steel plenum pan bolted to the underside with a gasket sealing them. Because the steel plate and aluminum manifold expand at different rates, over years of heat cycling the steel plate shifts and tears the gasket. Manifold vacuum then draws crankcase oil mist and blow-by up through the failed gasket into the intake runners, most notably feeding cylinder #8 on the V8. This is one of the most universally documented failures on 1992-1999 Magnum-powered Dakotas (the LA engines in 1990-1991 do not use this plenum-pan design). Chrysler issued TSBs 18-34-97, 18-48-98 and 09-05-00 addressing it.

HEMI engines with Multi-Displacement System (MDS) can develop a ticking noise from the MDS lifters. This is most noticeable at idle and during light acceleration. While often not immediately harmful, it can indicate lifter wear.