I/M Solutions 2012 Mike McCarthy Allen Lyons

Topics  Benefits of more stringent readiness  Using distance/number of warm-ups since code clear to improve readiness decisions  Impact of permanent DTCs  Readiness rules for diesel vehicles with aftertreatment

Benefits of Stronger Readiness  Klausmeier 1 reported vehicles with monitors not ready had higher IM240 emissions on average  California data confirms 1 “How Relaxed Readiness Requirements Affect I/M Program Benefits”, Klausmeier, IM Solutions 2011

ASM Failure Rate Correlates with Unset Monitors

So Do Average ASM Emissions  Trend Holds For: Both ASM Modes All Pollutants All Model Year Groupings

Maximizing Benefits  Requires balance between: Convenience: too tight rejects too many vehicles Emission Reductions: too loose foregoes potential reductions  Up to 25% of tested vehicles pass with one or more unset monitors

Understanding the Data  Readiness rates biased by: Pre-inspection code clearing ○ Legit: Last minute repair work ○ Not so legit: Attempts to clear codes and meet readiness before MIL illuminates again Existing readiness rules ○ Technicians/motorists adjust to the rules CA changed from 2 to 1 not ready on MY Number of vehicles with 2 not ready dropped 70%

Roadside Data: A Better In-Use Snapshot

Finding the Balance: Options with highest emission reductions combined with acceptable readiness are best Example: MY vehicles

New On-Board Data Can Help to Refine Readiness Rules  Using additional on-board data can help to fine tune readiness criteria and handle special cases  Distance/Number of Warm-ups Since Code Clear  Permanent Fault Codes

Distance/Warm-ups Since Code Clear (background)  Vehicles are required to track: miles since fault memory last cleared Warm-up cycle count since memory last cleared  Unset readiness = memory cleared ‘recently’ New data tells you exactly how recently  Applies to 2005 and newer CAN protocol vehs. Required for all MY vehicles

Distance/Warm-ups Since Code Clearing  Allow I/M programs to tell difference between unset readiness for: monitors that don’t run frequently for owner And Recent code clearing  Can be used to balance tighter readiness Ex: only allow an unset monitor if a minimum distance and/or warm-up counts is exceeded

Examples 1. Base Requirement: All monitors except evap must be ready Exception: Allow one additional monitor not ready if warm-up cycle counter is > 100 (est ~30 days on average) 2. Vehicle initially rejected for unset monitors Provide exemption if vehicle returns with warm up cycle and mileage counters showing substantial additional operation (e.g., 50 warm ups and/or 200 miles)

Permanent DTCs – What and When?  Phase-in: Model Years  Look like the same codes that exist today (Pxxxx) But not erasable by scan tool or battery disconnect And they do not command the MIL on  Only the OBD system itself can erase the code After that very same monitor has run and passed  These DTCs are not read with Mode $03 (what all IM programs use today) Available through Mode $0A

Permanent DTCs – Why?  Better than readiness indicators Unset readiness = maybe car had a fault ○ And if it did, who knows what the fault was? Permanent DTC = 100% proof car had a fault ○ And system has not yet verified fault is gone  No crazy drive cycles to set readiness Only need to drive the car to run that one monitor  ‘Rejecting’ a car with a Permanent DTC Rejects only those cars that definitely had MIL on Excludes recent dead/disconnected batteries, other service actions, etc.  Should reduce dependence on readiness Absence of permanent DTC strong indicator that vehicle is ok even if some readiness is incomplete

Diesel Readiness Challenges  Historically: Diesels had few emission controls (and thus, few monitors) Monitors could run on most driving cycles Worst case was monitors that require a cold start  Introduction of many new emission controls (and monitors) on models creates new paradigm Especially particulate matter (PM) filters

PM Filter Characteristics  Filter passively traps PM Takes hundreds/thousands of miles to fill  Vehicle initiates self-cleaning (regeneration) only when necessary Trapped PM burned off Temporarily increases emissions and reduces fuel economy  Can be weeks (or more) between regenerations

PM Filter Monitoring  Initial monitoring strategies (delta pressure across filter) typically tied to regeneration event  NMHC catalyst monitor also typically tied to regeneration event  Both can significantly prolong readiness setting

Readiness Monitors for Diesels Gasoline Readiness used through 2009MY  Misfire  Fuel System  Comprehensive Components  Catalyst  Evaporative System  A/C  O2 Sensor  O2 Heater  EGR/VVT New Diesel Readiness used For 2010+MY  Misfire  Fuel System  Comprehensive Components  NMHC Catalyst  NOx Catalyst  Boost Pressure  Exhaust Gas Sensor  PM Filter  EGR/VVT

Implications  Requiring all monitors set to ready (or even <1 or 2) may reject too many vehicles Could take vehicles many weeks or months to get ready  Readiness exceptions for aftertreatment monitors probably needed Target specific problem monitors rather than ‘any 1’ type approach  Downside: These are critical emission controls

Long Term Solutions  Permanent fault codes on vehicles so equipped Prevents benefit losses due to code clearing Still requires potentially long wait for monitor to run ○ But only if that particular monitor recently failed  Future monitors getting better PM sensor will decouple monitoring from regeneration Technology and ARB regulation will drive more frequent in-use PM monitoring Future NMHC catalyst monitors still likely to be tied to regeneration (and thus, slow to set readiness)