Hi everyone, I've been dealing with this issue for a while and I'm completely stumped. Hoping someone here has seen this before.
Volvo V40 2.0 diesel 120hp
The car stutters/jerks but ONLY under very specific conditions:
- Only when the engine is fully warmed up to operating temperature
- Only at light/gentle throttle input
- When cold - drives perfectly smooth, no issues at all
- Under full load/acceleration - completely smooth, no problems whatsoever
- No fault codes showing on diagnostics
- Sensor readings all look normal on live diagnostics
What I've already tried and eliminated:
- EGR valve - blanked physically AND disabled in software - still stutters
- Swirl flaps actuator - unplugged - still stutters
- MAF sensor - cleaned - no improvement
- MAP sensor - cleaned - no improvement
The key clue: When I unplug the MAP or MAF sensor the car goes into safe/limp mode and the stuttering completely disappears. As soon as I plug it back in and engine warms up - stuttering returns. This makes me think the issue is somehow related to boost pressure readings.
Current theory: Possibly a hairline crack in one of the intercooler pipes that only opens up when the engine/rubber is hot, causing a boost leak that the MAP sensor picks up and tries to compensate for, causing the stutter. In safe mode ECU uses fixed values and ignores the pressure fluctuations hence no stutter.
Has anyone seen anything like this? Any ideas would be greatly appreciated!