Emissions Air is made up of : s 21%O2 s 78%N s 1% other gasses (mostly argon)

Emissions

Air is made up of :

21%O2 78%N 1% other gasses (mostly argon)

Fuel is primarily made up of :

Hydrocarbons (HC)

Perfect combustion

HC, O2, N2 in Heat, H2O, CO2 and N2 out

Imperfect combustion

Adds HC, CO, NOx and O2 to exhaust

Stoichiometric

Much of our emissions are related directly to A/F mixtures

Theoretical best A/F ratio for emissions, economy, performance is 14.7:1

14.7 pounds of air to 1 pound of fuel

Think about it

Gasoline weighs 6 pounds per gallon Air weighs 1 pound per 100 gallons At 15:1 it takes 9000 gallons of air to

burn 1 gallon of fuel– 9000 Gallons of air is equal to a single car

garage

HC - Hydrocarbons

Unburned fuel Currently measured in parts per million

(ppm)

Common causes of high HC

Missfiring will cause HCs– Ignition – Mechanical – Lean

A/f ratios off either way Timing too advanced

– Cools exhaust and cylinder walls

Not so common causes of HC

Quench areas in combustion chamber– Carbon – Poor combustion chamber design

Cam profiles too aggressive

CO - Carbon monoxide

Currently measured in % EXTREMELY deadly gas!!! Partially burned fuel Too much fuel or too little O2

– Combustion process ran out of air CO directly related to a/f ratios

Causes of high CO

Any thing that will cause a rich fuel mixture– Sensor malfunction– Carburetor or injector failures– Diluted oil

Hard to use as an A/F guide over 15:1 due to flattening out of curve– Must use O2 above stoichiometric

O2 - Oxygen

Currently measured in % Unused air in exhaust O2 directly related to A/F Can also come from dilution

– Air pump, exhaust leaks Missfires will raise O2 If O2 is > 5% and vehicle running OK then it

must be from dilution

CO2 - Carbon dioxide

Currently measured in % Byproduct of complete combustion Peak indicates good A/F Any problems pull CO2 away from peak Used by Washington State to determine

exhaust system integrity

NOx - Oxides of nitrogen

Created when peak combustion temps. exceed 2500F

Causes of high NOx

Advanced timing Inoperative EGR Carbon build up Anything that overheats combustion

chamber

Smog, what is it?

Ground level ozone - O3 Three ingredients; HC, NOx and

sunlight CO is a pollutant all by itself

State emissions testing

Attainment areas vs. non-attainment areas– Ozone and/or CO

Centralized vs. non-centralized testing

ASM test

Loaded test with constant load with a CVS

Idle test With or without an evaporative

emissions test Test all three gasses

Washington State test

Variation of a ASM test Loaded cruise test except special

vehicles Idle test No NOx measuring in effect yet

IM240 test

Varying load test with a constant volume sampler

Idle test Evaporative emissions test Testing all three gases Visual inspection

Remote sensing devices

Like photo radar Used in California / Colorado

Emission Controls

PCV systems

Purpose of PCV

Control of blowbye gasses (HC) Reducing moisture and acids extending

oil life

PCV history

Road draft tube was responsible for 20-25% of vehicles emissions

Completely sealed systems on all domestics since 1968

Components of PCV

Breather to filter incoming air PCV valve

– Calibrated vacuum leak to intake manifold– Controls flow rates based on strength of

vacuum– Eliminates backfiring path to crankcase

Bleed orifice type / dual bleed type

PCV system problems

Can flow up to 20% of the total a/f mixture at idle

Plugged system could cause high CO at idle

Stuck open valve could cause lean or high idle speed

PCV system diagnosis / testing

Valve should snap back at idle Rattle test Cheap valves pass both tests but could

flow wrong Inspect breathers for plugging Oil dilution

– 1% Change = too much dilution or blowbye

Inspect / replace at tune up intervals

Evaporative emissions system

Evap system purpose To control HC during fuel evaporation

Evap system components

Gas cap– Important seal of system– Easily over looked– Allows air in but pressure out only if >1 psi

Vapor liquid separator

Evap system components

Canister– Stores evaporating vapors

– Approx. 1.5 Lbs. Activated charcoal

– Can hold twice it’s own weight in fuel

– Chrysler used the crankcase in 1971 Vapor line(s) from tank(s) Carb bowl venting

– Electronic solenoids

– Switching with purge valve

Evap system operation (purging)

Uses stored fuel vapors in canister Variable type-hose to air cleaner

snorkel Constant purge type-vacuum to

manifold– Uses TVS and orifice

Evap system operation (purging)

Demand system– None at idle– Uses ported vacuum as control– Manifold vacuum does purging– Needs TVS

Computer controls OBDII diagnostics

Evap system problems

Failed purge valves / diaphragms rupturing

Plugged filters Failing TVS can cause cold flooding Loaded canister due to over full tanks Charcoal in carb. bowl indicates

defective canister

Early fuel evaporation systems

EFE system purpose

Helps a/f mixture vaporize on cold engine

Provide good cold driveability (cold air too dense and leans out mixture)

Improve cold emissions

EFE system purpose

Warms intake to prevent condensation of fuel

Prevents icing in carbs (temps can drop 66f when fuel vaporizes)

Four types of EFE

1. T.A.C. (thermostatic air cleaner) 2. EFE grid 3. Coolant heated intakes and throttle

bodies 4. Heat riser valve

T.A.C. components

Mode door– Cold air position for warm eng.– Warm air position for cold eng.

Uses manifold vacuum and vacuum motor to move mode door

Heat stove and pipe– Primary failure of emission tests

T.A.C. components

Sensor– Bleeds off vacuum at 100 - 120f– Must bleed off vacuum - can not trap it

Wax bulb type Manual movement (older asians)

T.A.C. problems

Stuck in hot air position will cause ping / NOx– Often caused by a plugged bleed off hole

Any missing piece can cause cold driveability problems

Cracked manifold sucks exhaust into air cleaner

EFE grid components

Electrical heater – Usually only, on carburetors and only on

primary bore(s) Commonly ceramic

EFE grid operation

Heats and mixes a/f mixture Controlled by switches or relay

– Usually powered up cold only

EFE grid problems

Grids melt Switches stick on Heater element opens

Coolant passages

Primarily icing controls Also helps warm intakes

Heat riser valve purpose

Directs exhaust to underside of intake manifold

Prevents condensation Improves vaporization Not necessary on PFI engines

Heat riser valve components

Vacuum with rod– Uses TVS

Bimetal spring On V engines valve will plug off one

side of exhaust when cold

Heat riser problems

Binding on shaft Stuck in cold mode causing ping and

NOx by overheating incoming a/f mixture

Valve disintegrating

Air systems purpose

To pump or allow air to be sucked into exhaust system– Completes combustion– Dilutes exhaust gasses– Gives O2 to cats– Heats O2 sensor

Two types - air pump and air suction (pulseair)

Air pump system

Air pump

Belt driven vane and rotor pump Some use electric air pumps Some means of filtered air intake

– Often using a centrifugal filter 1/2 Hp draw on engine

Diverter and gulp valves

Purpose: divert AIR away from exhaust on decel to prevent backfire

Gulp dumps AIR to intake– Similar to a decel valve / mixture control

valve Vacuum or electric controlled

Check valve

Purpose: to prevent exhaust from coming up into AIR system

Failed valves can cause melted hoses and diverter valves

Air manifolds and pipes

Rotting out causing backfire / exhaust leaks

Air on CCC cars

Computer controls routing of AIR system

Upstream cold vs. downstream warm Still diverts totally away during decel

Pulseair system

No pump Uses negative exhaust pulses Reed valves Can still divert or block off AIR Can be computer controlled Often mounted to air cleaner

Pulseair system problems

Back firing on decel if reed valves leak Melted stuff is melted if valves leak Can stick upstream

EGR systems

Purpose : flows exhaust gas into intake to lower combustion temps which lowers NOx

EGR details

Exhaust supports no combustion Dilutes a/f mix and slows combustion

slightly First used on Buicks in 1972, common

in 1973 Does not affect a/f ratios

Three methods to obtain EGR

Floor jets– Egr at all times

Cam grinds– Egr at all times

Egr valves

Control of EGR needed for three reasons

Idle; can not support dilution and little NOx

Cold; poor driveability, no NOx, not all engines

WOT; limits power and less NOx due to richer a/f

EGR valve is a means of controlling EGR flow

Basic systems use ported vacuum to control and limit operation and a TVS to eliminate cold operation

Some use a vacuum amplifier– Works like vacuum relay

Often will have delay orifices and valves

Backpressure Transducer

Limits with exhaust pressures Exhaust pressures good load indicator Can modulate valve Many valves have built in transducers

– Positive valves vs. Negative valves

Electronic controls

Can use vsv’s to control EGR via ECU Electric valves

– Using solenoids to control operation Sensors

– Position (EVP)– Exhaust pressure (PFE)– Temperature switch

Problems

Inop valves cause high combustion temps = pinging =NOx

Plugged EGR passages common Too much EGR = lack of power, surge Stuck open at idle causes rough idle

due to excessive dilution

EGR testing

Egr movement under load– Some need to see VSS input

Vacuum present at valve Lift up at idle to check passages

Catalytic converters

Two types of converters

Oxidizing Reducing May be in one case

Oxidizing

First in 1975 Converts HC and CO to H2O, CO2 and

heat Uses precious metals platinum and

palladium

Monolith construction (honeycomb)

Ceramic coated with p&p Lots of surface area Very brittle Most common

Pellet construction

Aluminum oxide pellets coated with p&p Not as much surface area Very heavy Not easily damaged

Oxidizing operation

Needs O2 to convert HC and CO to H2O AND CO2– Gets O2 from lean a/f ratios, AIR systems,

missfires Light off at 500f, average temps 1400f

inside, 700f outside Abbreviated OC

Reducing cat

Converts NOX into N2, CO2, O2 Needs lack of oxygen and some CO to

work– Likes richer mix– Missfires provide too much o2

Uses rhodium

Three way or dual bed

First part or bed reducing

Gives off O2 to help second bed Needs CO which second bed eliminates

Second part oxidizing bed

Uses O2 from first part Can use air into cat behind first bed

Needs to be close to stoichiometric to work

Only found on cars with closed loop fuel

Problems and testing all types

Plugging– Abuse– If not abuse must find cause before

replacing Rich Leaded fuel Missfire Air system

Symptoms: Vacuum not always accurate Back pressure reading of > 3psi is

excessive Test at back pressure transducer, O2

sensor, AIR fitting, EGR

Efficiency loss

Symptoms: Loss can be due to lead, coolant, oil,

miles Aftermarket not as effective DO NOT USE USED CATS OBDII efficiency monitor

Efficiency testing

Temps 100-200f increase across cat Intrusive method

– Egr, AIR pipes (must seal), drilling hole– Need thin probe– Rivet holes up– Not at O2 sensor

Using the bible sticker underhood to id components