The 2017 Acura TLX experiencing misfires specifically under load with P0303 indicating cylinder 3 issues presents a diagnostic pattern pointing to specific causes. Load-dependent misfires behave differently from idle misfires and require targeted investigation.
Understanding Load-Dependent Misfires
Misfires occurring under load (acceleration, climbing hills) but not at idle indicate components that work adequately under low-demand conditions but fail when combustion pressures and temperatures increase. This pattern narrows diagnostic focus to specific causes.
Common Causes of Load Misfires
Weak ignition coils may fire at idle but fail under boost or high compression. Spark plugs with worn electrodes can't bridge the increased gap under load. Fuel injectors providing marginal flow fail to deliver adequate fuel during acceleration. Carbon deposits affecting valve sealing become problematic under higher cylinder pressures. Low compression in the affected cylinder shows up more under load.
V6-Specific Considerations
The TLX V6 with VCM may experience different wear patterns on affected cylinders. Cylinder 3's position affects access for diagnosis. The V6's higher compression compared to the four-cylinder makes it more demanding on ignition components under load.
Diagnostic Approach
Verify the misfire occurs specifically under load by monitoring data during driving. Test ignition system capacity—coils and plugs may test good at idle but fail under load conditions. Check fuel pressure under load to ensure adequate delivery. Perform compression test comparing all cylinders.