P. 1 

# OAR Box 1830 Prepped byOllie Stewart



### Document

Number: 

# 31 ) IV-B-2

7 Docket Number: 

# A-87-1 1

Printed 11/13/20087:20:52 AM Sheet 31 of 232P. 2

I* 0 "*** 

## |V-B-2 r

UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y 

### JA N 

### 2 A199/

1 

### j |

MEMORANDU M kN N ARBOR . MICHIGA N 4810 5 

### JA N 

### B 5 1S9

^ OFFIC E O F AI R AN D RADIATIO N

SUBJECT : FROM : THRU : TO : Estimat e o f Reductio ni nEvaporativ e Syste mPurg e

Failure s Resultin g fro mRecen t EP AAction s Da nBarba , Mechanica l Enginee r \)<Lv\ iSeJ-Jv^ Engin e an d Vehicl e Regulation s Branc h Do nKopinski , Projec t Manage r Engin e an d Vehicl e Regulation s Branc h Glen nPassavant , Branc hChie f Specia l Regulator yProject s Branc h Thi s memorandu mestimate s th e reductio ni nevaporativ e syste m purg e failure s resultin g fro mInspectio nan dMaintenanc e (I/M ) program s [5 7 F R52950 , Novembe r 5 , 1992 ] an donboar ddiagnosti c (OBD ) system s [5 8 F R9264 , February.19 , 1993] . Percen t reduction s i nfailur e rat e ar e estimate dove r th e ful l usefu l lif e o f a vehicle , a s define d unde r th e Clea nAi r Ac t [5 8 F R29409 , Ma y2 0 1993] . Th e attache d figur e show s ho wevaporativ e syste mfailur e rate s ar e modele d i nMOBILE5 1 . Th e dat a show s tha t th e purg e failur e rat e i s fairl yconstan t (3. 5 percent ) ove r th e usefu l lif e o f th e vehicl e (50,00 0 mile s fo r curren t vehicles) . I t i s reasonabl e t o expec t tha t th e failur e rat e wil l b e maintaine dove r 100,00 0 mile s a s a resul t o f ful l usefu l lif e requirements . Thus , i nthi s analysis , th e purge-failur e rat e i s projecte dt o b e 3. 5 percen t ove r th e ful l usefu l lif e o f th e vehicl e (1 0 years/100,00 0 miles ) . Th e enhance d I/ Mprogra mrequire s vehicle s t o underg o a functiona l tes t o f th e purg e system . I f a vehicl e fail s th e test , th e purg e syste m

mus t b e repaired . Althoug hbasi c I/ Mdoe s no t requir e a functiona l test , th e fina l I/ Mrul e require s state s t o revis e thei r stat e implementatio nplan s (SIPs ) t o incorporat e inspectio no f th e OB D system , whic hinclude s a purg e syste mchec k simila r t o th e enhance d I/ Mpurg e test . Thus , i t i s expecte dtha t faile d purg e system s wil l b e identifie dan drepaire di nbot hbasi c an d enhance d I/ Mareas .

1,T Draf t MOBILE 5 Ho t Soa k an d Diurna l Emissions, " handou t fro m EP AMOBILE 5 Workshop , Jul y8 , 199 2 (Docke t A-89-18 , ite mIV-B-8) .P. 3



### Th e regulatorysuppor t documen t fo r I/ Massume d tha t al l purg e failure s caugh t b

yI/ Mtesting woul d b e repaired . However , becaus e inspection s ar e no t normall yrequire d o nbrand ne wvehicles , purg e failure s wil l no t b e identifie d unti l afte r th e vehicl e i s a t leas t on e yea r old , assuming anannua l inspection . I nfact , becaus e I/ M inspection s ar e tie d t o annua l vehicl e registratio nrequirement s i n man ystates , a ne wvehicl e mayno t b e require d t o receiv e an inspectio nunti l i t i s almos t tw o year s old . Th e regulatorysuppor t documen t fo r I/ Massume d n o vehicle s wil l receiv e aninspectio nduring th e firs t yea r o f vehicl e operatio nan

d 2 5 percen t o f th e vehicle s wil l receiv e aninspectio n during th e second yea r o f operation. 2 

### Afte r th e second year , al l vehicle s ar e inspecte d an d th e repai r rat e i s 10 0 percent . Th e averag e inspectio nrate , an d thu s th e averag e reductio ni npurg e failures , ove r th e 1 0 yea r ful l usefu l lif e o f a vehicl e i s approximatel y8 0 percen t ([1*0. 0 + 1*0.2 5 + 8*1.0]/10) . I narea s withou t I/M , OBD system s alon e ar e expecte d t o resul t i na substantia l reductio ni npurg e failur e rate . I na survey conducte d fo r EP Ab yWestat , Inc. , 6 0 percen t o f vehicl e owner s sough t repai r afte r a dashboar d ligh t indicate d anengin e malfunction. 3 

### Thus , i t canb e estimate d tha t 6 0 percen t o f purg e failure s caugh t b

yth e OBD systemwil l b e repaire d i narea s withou t I/M . Attachmen t

2 1 1 

### I/ MCost , Benefits , an d Impacts, " EPA , Novembe r 1992 , 3 

### "Surve yo f Vehicl e Owner s i nth e On-boar d Diagnostic s Program, " prepare d fo r EP Ab yWestat , Inc. , 1 8 Jul y199 0 (docke t A 90-35 , item

II-A-6 )

## M0BILE 5 Pressur e an d Purg e Failur e Rate s

mi 

### Failure

Rate (% ) 

### 7 0 6 0 5 0 4 0 3 0 2 0 

## 1 0 

# + + + + + + ~ Pressur e

" " Purg e

—Pres s o rPurg e



### 2 0 4 0 6 0 8 0 10 0 12 0 14 0

Mileag e ( x1000 ) 16 0 18 0 20 0

-o