TSB-150127

Low Pressure Regulator Oscillation Causes Idle Surge
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SB-10058917-8141
Technical Service Bulletin Number
TSB150127
Technical Service Bulletin
Subject
Low Pressure Regulator Oscillation Causes Idle Surge
Issue
Affected low pressure regulators, Part Number 2883325, can cause intermittent engine surging
at idle and fault codes 6396 or 1861. The pressure oscillations have no impact on pressure
readings in INSITE™ electronic service tool or with a mechanical gauge, but can affect the gas
mass flow sensor measurement.




Calibrations released before 27 March 2015 may log fault code 1861 - Aftertreatment
Intake Oxygen Sensor - Data Erratic, Intermittent, or Incorrect.
Calibration released on or after 27 March 2015 may log fault code 6396 - Engine Exhaust
O2 Sensor Closed Loop Operation - Data Erratic, Intermittent, or Incorrect. The ECM has
detected a lean or rich condition for a sustained period of time.
Verification
Product Affected


ISX12 G CM2180 EJ
Most low pressure regulator performance issues are reproducible at idle but may require the
engine to be at a given temperature (operating temperature or ambient). Fault code 6396 or
1861 may be associated with an oscillating low pressure regulator.
Perform the following steps to recreate the customer complaint of idle surge.
NOTE: Once idle surge greater than 100 rpm is replicated go to step 6 in the instructions
below. Do not operate the engine above idle with the gas mass flow sensor unplugged.
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Instructions for diagnosing low pressure regulator oscillation observed as idle surge.
1. Connect to electronic control module (ECM) with INSITE™ electronic service tool.
a. Take an ECM image and go to step 2.
2. Start engine and bring to operating temperature.
a. If idle surge occurs, go to step 6.
b. If no surge at idle is observed, go to step 3.
3. Perform three throttle sweeps from idle rpm to high speed governor. INSITE™
parameter, Maximum Engine Speed without Vehicle Speed, is generally set at 1400 to
2400 rpm.
a. If the engine misfires, begins to surge, or the throttle becomes unresponsive and
will not reach high speed governor go to step 6.
b. If no misfire or surge is observed, go to step 4.
4. Turn keyswitch to OFF position. Restart engine. Perform two quick throttle sweeps.
Repeat sequence 1 time.
a. If idle surge occurs or the throttle becomes unresponsive go to step 6.
b. If no misfire or surge is observed, go to step 5.
5. Perform a short test drive including smooth acceleration and 2 key off and restart cycles.
a. If misfire or surging is observed, go to step 6.
b. If no surge, misfire, or low power is observed, the low pressure regulator has
passed and is acceptable for service. Clear fault codes and return vehicle to
service.
6. Unplug gas mass flow sensor from the idling engine and determine if idle improves.
a. If idle surge is corrected by unplugging the gas mass flow sensor, go to resolution
section.
b. If idle surge or misfire is not corrected, use published troubleshooting to diagnose
other symptoms or fault codes. If no symptoms or faults exist, escalate to technical
support. Do not replace the low pressure regulator or return vehicle to service.
Resolution
Perform the following only if indicated by verification steps above.










Replace low pressure regulator with a part built on or after 15 June 2015 (DOM 16615).
Clear fault codes with INSITE™ electronic service tool.
Perform fuel system table reset with INSITE™ electronic service tool.
Retest starting with step 2 in verification section.
If symptoms reoccur escalate to technical support.
Screening went into effect on 15 June 2015 to identify oscillating low pressure regulators.
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Figure 1, Low Pressure Regulator Part Number and Date of Manufacture




Low pressure regulator part number.
Date of manufacture. Format: DDDYY
 DDD: Day of year
 YY: Two digit year
Service Parts Availability
Service part is available. Low pressure regulator, Part Number 2883325
Associated Publications
Table 1, Associated Publications
Manual
Type
Engine
Bulletin
Number
Procedure Title
Procedure
Section
Service
Manual
ISX12 G
CM2180 EJ
4310682
Low Pressure
Regulator
Refer to Procedure
005-047
5
Warranty Statement
The information in this document authorizes specific changes to the repair practice for failures
covered under product warranty coverages.
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Document History
Date
2015-7-27
Details
Module Created
Last Modified: 30-Jul-2015
Copyright © 2000-2010 Cummins Inc. All rights reserved.
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8/3/2015