Detroit Diesel — Performing a Fuel System Test using minidiag2
Testing & diagnosis · Fuel system / unit pumps
From a Detroit Diesel service manual — check it applies to your exact model before use.
Before you start
- PERSONAL INJURY: remove loose items of clothing and jewelry; tie back long hair near an operating engine.
Procedure
- Plug minidiag2 into the truck diagnostic connector and connect to the VCU/DDEC-ECU system.
- Choose option 4 – Routines.
- Select option 4 – Idle Smoothly Balance and check each cylinder value.
- Look for option 5 – Impact Time Delay under Routines and check each cylinder value.
Tools required
- minidiag2 Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Idle Smoothly Balance range: -3% to 3%
- Impact delay time range: 1.2 to 2.1 milliseconds
Source: Detroit Diesel service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.