APPENDIX A

FINAL TECHNICAL SUPPORT DOCUMENT

Amendments to the New Engine Tier 4

Off-Road Compression-Ignition Regulations
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FINAL TECHNICAL SUPPORT DOCUMENT: TIER 4

Note: This appendix provides background information regarding the Tier 4 Off-Road 

Compression-Ignition Regulations and Test Procedures approved by the Air 

Resources Board on December 16, 2011, and with subsequent conforming 

modifications authorized under Resolution 11-41. Revisions to the original 

Appendix R, published on October 26, 2011, as part of the Staff Report: Initial 

Statement of Reasons, are meant solely to indicate the transition from a 

proposed document to a final document, and are indicated either by underlined

type to indicate additions (except that some existing headings within the 

document were underlined originally for emphasis, and remain so, and thus do 

not constitute new language) or by strikeout to indicate deletions.
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Detailed Descriptions of Proposed Final Amendments: Tier 4 Off-Road CI 

Engines

I. DEFINITIONS

This section provides background on key terms that staff is proposing for have 

been incorporationed or modificationed in to the California off-road diesel 

regulations and/or test procedures.

• 2011 and Later Test Procedures:

In keeping with the precedence for incorporating test procedures and defining a 

standardized abbreviation for them in the definition section §2421 of the off-road 

diesel regulation, staff’s proposal assigns the updated test procedures titled 

“California Exhaust Emission Standards and Test Procedures for New 2011 and 

Later Tier 4 Off-Road Compression Ignition Engines, Parts I-D, I-E, and I-F,” have 

been assigned to new subparagraph (a)(4)(B) as the 2011 and Later Test 

Procedures. The previous version of the test procedures are relocated to new 

subparagraph (a)(4)(A), previously just (a)(4), and retitled to indicate model 

year-limited applicability through the 2010 model year (i.e., 2008-2010 Test 

Procedures).

• Constant Speed Engine:

Staff proposes to align with tThe definition of a “constant speed engine” has been 

aligned with the federal definition of “constant speed engine/operation” in 40 CFR, 

part 1039.801. The new definition more accurately describes the normal 

operation of a constant speed engine, including a more realistic allowance for 

fluctuating engine speed under changing loads. The revised definition is 

appended to the existing definitions of “constant speed engine” in new 

subparagraph (a)(15)(C) with referenced applicability to 2011 and later model 

year engines,

• Date of Manufacture or Build Date:

The proposal aligns with definition of “date of manufacture” has been aligned with 

the federal definition of “date of manufacture” described in 40 CFR, part 1068.30 

to standardize the assignment of engine build dates. Further, the use of the term 

in §2423(j)(1) of the regulation to characterize the type of power to be included on 

the emissions label for replacement engines necessitates the creation of a new 

definition for “Date of Manufacture” in §2421(a)(19). All subsequent definitions 

are renumbered to preserve alphabetical order.
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• Carryover:

Staff proposes to alignThe definition of “carryover” has been aligned with the 

federal definition of “carryover’ in 40 CFR, part 1039.801 to ensure uniform criteria 

for the application of data from previous model year engine families.

II. EMISSION STANDARDS

• Proposed Alternate Tier 4 NMHC+NOx standards and FEL Caps.

Table R - II.A; Tier 4 Exhaust Emission Standards

(grams per kilowatt-hour)

MAXIMUM

ENGINE 

POWER

MODEL YEAR TYPE

PM NMHC+

NOX NMHC NOX CO

grams per kilowatt-hour

56≤kW<75

2012-2014

PHASE-IN

0.02

- 0.19 0.40

5.0

PHASE-OUT 4.7 - -

or/ ALT NOX - 0.19 3.4

or/ ALT NOX+NMHC 3.5 - -

2015 and later FINAL - 0.19 0.40

75≤kW<130

2012-2014

PHASE-IN

0.02

- 0.19 0.40

5.0

PHASE-OUT 4.0 - -

or/ ALT NOX - 0.19 3.4

or/ ALT NOX+NMHC 3.5 - -

2015 and later FINAL - 0.19 0.40

130≤kW≤560

2011-2013

PHASE-IN

0.02

- 0.19 0.40

3.5

PHASE-OUT 4.0 - -

or/ ALT NOX - 0.19 2.0

or/ ALT NOX+NMHC 2.1 - -

2014 and later FINAL - 0.19 0.40
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• Proposed ALT NOx FEL Cap Applicability

Table R - II.B; Tier 4 Family Emission Limit (FEL) Caps

MAXIMUM

ENGINE POWER FEL TYPE MODEL YEAR

PM NOX NMHC+

NOX

grams per kilowatt-hour

56≤kW<75

Phase-in

2012-2014 0.04

0.80 -

Phase-out - 7.5

Alternate NOx Std

2012-2013

0.04

3.0 - 2012-2014 4.4

Alternate NOx+NMHC Std 2012-2013/2014 0.04 - 4.7

Primary 2014/2015 and later 0.04 0.80 -

ALT 20% PM 2012-2015 0.40 -

ALT 20% NOX 2012-2015 4.4 -

ALT 20% NOx+NMHC Std 2012-2015 - - 4.7

ALT 5% 2016 and later 0.40 4.4 -

75≤kW<130

Phase-in

2012-2014

0.04

0.80 -

Phase-out - 6.6

Alternate NOx Std

2012-2013 3.07 -

2012-2014 3.8 -

Alternate NOx+NMHC Std 2012-2013/2014 - 4.0

Primary 2014/2015 and later 0.80 -

ALT 20% PM 2012-2015 0.30 -

ALT 20% NOX 2012-2015 3.8 -

ALT 20% NOx+NMHC Std 2012-2015 - - 4.0

ALT 5% 2016 and later 0.30 3.8 -

130≤kW≤560

Phase-in

2011-2013

0.04

0.80 -

Phase-out - 6.6/6.4

Alternate NOx Std 2011-2013 2.7 -

Alternate NOx+NMHC Std 2011-2013 - 4.0

Primary 2014 and later 0.80 -

ALT 20% PM 2011-2014 0.20 -

ALT 20% NOX 2011-2014 3.8 -

ALT 20% NOx+NMHC Std 2012-2015 - - 4.0

ALT 5% 2015 and later 0.20 3.8 -
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III. DIFFERENCES BETWEEN CALIFORNIA AND FEDERAL REGULATIONS

A. PROPOSED NEW NON-ALIGNMENT REQUIREMENTS

1. Replacement Engine Labeling

Staff proposes to include aAdditional information is required on replacement 

engine labels to assist ARB’s in-use off-road diesel modernization programs that 

rely on accurate power and emissions performance information to ensure the 

calculation of appropriate fleet emission averages. In addition to the proposed

harmonized statement of compliance in §2423(j)(1) of the regulations and 

§1068.240 of the Test Procedures, the new California label would also includes

“engine power,” “reference family name,” and “date of manufacture.” These 

additional parameters would provide end-users with the information necessary to 

accurately register their engines and equipment, and would should greatly 

enhance the ability of ARB’s field inspectors to enforce the regulations. Federal 

regulations do not include a similar requirement because U.S. EPA does not 

currently regulate in-use off-road engines, making knowledge of these parameters 

less critical outside of California. 

2. Preliminary Approval

ARB is not aligningStaff proposes not to align with a U.S. EPA amendment to 

§1039.210 that gives manufacturers the assurance that preliminary approvals 

(i.e., those given prior to the approval of a manufacturer’s certification application) 

will not usually be reversed apart from the discovery of new information contrary 

to the findings that resulted in the preliminary approval. Rather than to provide 

potentially specious global assurances, staff prefers to continue the practice of 

working with industry on a case-by-case basis to provide direction on certification 

requirements and options prior to application. Ultimately, however, it is the 

manufacturer’s responsibility to ensure that it has met the letter of the law 

regarding certification requirements. The issuance of an Executive Order, after 

reviewing an application for certification, is, and should remain, the official means 

for granting binding approval.

3. Untracked Replacement Engine Provision

ARB is not aligningStaff proposes not to align with an amendment to §1068.240

permitting a small number of replacement engines to be exempt from tracking 

requirements (e.g., labels). As noted above in the discussion for replacement 

engine labeling, properly labeled engines are extremely important for the correct 

implementation and enforcement of California’s in-use off-road fleet 

modernization programs. Even a small number of engines without labels could 

hamper registration and enforcement efforts sufficiently to compromise the 

effectiveness of those programs and the emission reduction benefits associated 
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with them. This is not as large a concern federally because U.S. EPA does not 

regulate in-use off-road engines like California. 

4. Engine Definition

ARB is not aligningStaff proposes not to align with U.S. EPA’s definition of an 

engine as an engine block with an installed crankshaft, nor U.S. EPA’s definition 

of a partially complete engine as defined in §1068.240. Rather, staff chooses to 

remain flexible in its interpretation of what constitutes an engine, generally, an 

assemblage of systems and components that are capable of providing power and 

generating emissions. Nevertheless, the lack of a generic and formal “engine” 

definition is not necessary for compliance with the California regulation or any 

portion of the incorporated Test Procedures. The California regulations already 

provide for the labeling and final assembly of partially complete (or ““incomplete”) 

engines in §2423(l). This section, as noted below in the discussion on the rebuild 

labeling prohibition and supplemental label requirement is already a departure 

from federal requirements and would not support the federal definition of a 

partially complete engine.

B. PRIOR NON-ALIGNMENT REQUIREMENTS

Flexibility Engine Labeling

ARB requires the inclusion of a reference engine family name on the emission 

control label of flexibility engines to aid in the verification of emission levels by 

field inspectors 

Flexibility Engine Executive Orders

ARB requires that engines produced for use in flexibility equipment be covered by 

an Executive Order.

Rebuild Labeling Prohibition and Supplemental Label Requirement

ARB adopted a new §2423(l) during the previous amendment of the off-road 

diesel regulations that clarifies the categorization of remanufactured engines as a 

subset of rebuilt engines, thereby subject to the same requirements as rebuilt 

engines, and specifies labeling content for the different types of rebuilt engines.

Extension of Replacement Engine Reporting Requirements

ARB clarified that when replacing a California certified off-road diesel engine, 

equipment manufacturers are generally required to use the cleanest engines

available. This interpretation of existing language differs from U.S. EPA’s 

interpretation which states that the replacement engine must be “at least as clean” 

as the engine it replaces.
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In-Use Compliance/Recall Program 

ARB maintained the independent authority of California to investigate and recall 

engines found to be in violation of the regulations apart from U.S. EPA, if 

necessary.