Engine shuddering at 2.5k RPM and cruise

Tags: #problem · #jerking · #egr · #catalytic-converter · #conflict

Symptom. Multiple X80 owners report engine jerking/shuddering that occurs in two related situations: (1) consistently at around 2.5k RPM, and (2) while cruising at a steady 120-150 km/h on constant throttle/RPM. The jerk is described as light, and it stops if the driver accelerates harder, releases the gas completely, or downshifts. A related pulsing sensation at 1.5-2k RPM is also reported. Severity is minor and doesn't meaningfully affect drivability if the throttle is adjusted around it^12345678910.

Root cause — community divided. No single cause is agreed on. Candidates discussed: a fouled DAD sensor from crankcase gases, an EGR valve malfunction (a screenshot of an EGR-related fault code was shared in this thread), spark-plug fouling (plugs last checked 40-50k km prior), a catalytic converter issue, or simply a transmission quirk — some owners suggest it's the transmission hesitating/undecided between gears, which would be normal behavior rather than a fault. Similar complaints reportedly exist on Mazda 6 forums, suggesting a shared-platform characteristic rather than an X80-specific defect^12345678910. Conflict: root cause disputed between EGR, DAD sensor, catalytic converter, transmission behavior, and spark plugs — not resolved in this data batch.

Media

Screenshot of a diagnostic error-code display showing an EGR-related fault code

Related pages

• Low-speed jerking — multiple causes
• AKPP jerking — spark plug and fluid fix
• Cruise control behavior and limitations
• Engine chip tuning (ECU remapping)
• Engine "loses sync" and stalls — diagnosis

Sources

This page is compiled from 10 community messages. Every fact carries a numbered reference to its original author and message.

Last updated: 2026-07-24