ECU Remap — Mercury Marine QSD 4.2 350 350hp 704nm
The Mercury Marine QSD 4.2 350 350hp 704nm (Gasoline, 350 PS) can be tuned with a Stage 1 ECU remap to 420 PS — a gain of +70 PS without any hardware modifications. Our tuning files target the original ECU software and optimise parameters such as injection timing, boost pressure and fuel maps to unlock the full performance potential.
All tuning files at ecufiles.io are developed and tested by experienced engineers. The original ECU file is always preserved — the remap is 100% reversible at any time.
Frequently Asked Questions
What does an ECU remap do on the Mercury Marine QSD 4.2 350 350hp 704nm?
An ECU remap (chiptuning) modifies the engine control unit software to optimise parameters like injection timing, turbo boost pressure and fuel delivery. On the 350 350hp 704nm, this typically results in more power, better throttle response and improved fuel efficiency at part load.
How much power gain is possible with Stage 1 on the 350 350hp 704nm?
Stage 1 brings the 350 350hp 704nm from 350 PS to 420 PS — a gain of +70 PS. No hardware modifications are required, making it the most popular and cost-effective tuning option.
Is chiptuning reversible on the Mercury Marine QSD 4.2?
Yes. We always save the original ECU file before applying any remap. The tuning can be fully reversed to factory settings at any time.
How fast do I receive the tuning file?
We process orders Monday to Friday from 08:00–20:00 and Saturday from 10:00–16:00. Most tuning files for the Mercury Marine QSD 4.2 are delivered within 1–3 hours after uploading your original file.