Section 87.1
SPN 1325/FMI 31

This diagnosis is typically a misfire has been detected in cylinder #3.‪

Section 87.1.1
Cylinder #3 Misfire Detected

SPN 1325/FMI 31 indicates a misfire event on cylinder #3, conditions for this fault are:‪

• Engine speed: 1350 - 2200 rpm
• Engine load: Steady

Cylinder misfire can occur due to any of the conditions below:‪

• Injector - worn or faulty
• Fuel leak at transfer tube or high pressure fuel line
• Poor cylinder compression
• Valve lash maladjustment
• Cylinder kit failure
• Valve train failure

Check as follows:‪

1. Start and bring the engine up to operating temperature.
2. Using DDDL 7.x perform the “Compression Test” service routine:
   1. If cylinder #3 shows low compression, the issue is related to a possible mechanical failure such as valve lash, maladjustment, valve train damage etc. Repair the cylinder concern.
   2. If all cylinders are within 10% of each other, go to step 3 .

      Note: Engine must be at idle while using this routine

3. Using DDDL 7.x access the “ISB” service routine.
   1. If the “ISB” service routine results for cylinder #3 are +/- 100%, go to step 4 .
   2. If the “ISB” service routine results are not equal to +/- 100%, the fault may be intermittent. Continue to run the test for 3 minutes. If the above values are seen, go to step 4 .
   3. If ISC values are not +/- 100% after 3 minutes, obtain added information from the customer on the vehicle's operating conditions. Fault code “extended data” may be used in order to determine the engines operating range when the fault actually occurred. Obtain a DDDL log file of the condition and contact the Detroit Diesel Customer Support Center at 313–592–5800 for further instruction.

   NOTICE:
   Never re-use a high pressure fuel line or transfer tube.‪

4. Visually inspect the high pressure fuel line and transfer tube on cylinder #3 for any leakage or damage.
   1. If any leakage or damage is found, replace the high pressure fuel line, and transfer tube. Refer to "2.3 High Pressure Fuel Lines and Transfer Tubes" .
   2. If no leakage or damage is found, replace the #3 fuel injector, high pressure fuel line, and transfer tube. Refer to "2.4 Fuel Injector" .