according to the startup procedure described in § 1201.80.

(b) A speed tolerance of 1 m.p.h. above or below the theoretical speed and a time tolerance of ±0.5 sec. from that prescribed (or an algebraic combination of the two) may be accepted, if the speed vs. time relationship has been followed as closely as possible. Speed tolerances greater than 1 m.p.h. (such as occur when shifting manual transmission vehicles) may be accepted provided they occur for less than 2 seconds on any one occasion. Speeds lower than those prescribed may be accepted provided that the vehicle is operated at maximum available power during such occurrences. Further, speed deviations from those prescribed due to stalling are acceptable provided the provisions of § 1201.80 (f) are adhered to.

§ 1201.76 Dynamometer procedure.

(a) The vehicle shall be tested from a cold start. Engine startup and operation over the driving schedule make a complete test run. Exhaust emissions are diluted with air to a constant volume and a portion is sampled continuously during the entire test run. The composite sample, collected in a bag, is analyzed for hydrocarbon and carbon monoxide. A parallel sample of the dilution air is similarly analyzed.

(b) A fixed speed cooling fan (cooling capacity shall not exceed 5,300 c.f.m.) shall be positioned during dynamometer operation so as to direct cooling air to the vehicle in an appropriate manner with the engine compartment cover open. In the case of vehicles with front engine compartments, the fan shall be squarely positioned between 8 and 12 inches in front of the cooling air inlets (grill). In the case of vehicles with rear engine compartments (or if special designs make the above impractical) the cooling fan shall be placed in a position to provide sufficient air to maintain engine cooling.

(c) The vehicle shall be nearly level when tested in order to prevent abnormal fuel distribution.

(d) Flywheels, electrical or other means of simulating inertia as shown in the following table shall be used. If the equivalent inertia specified is not available on the dynamometer being used, the next higher equivalent inertia (not to exceed 250 lbs.) available shall be used.

(e) Power absorption unit adjustment. (1) The power absorption unit shall be adjusted to reproduce road load power at 50 m.p.h. true speed. The indicated road load power setting shall take into account the dynamometer friction. The relationship between road load (absorbed) power and indicated road load power for a particular dynamometer shall be determined by the procedure outlined in Appendix B or other suitable means.

(2) The road load power listed in the table above shall be used or the vehicle manufacturer may determine the road load power by the following procedure and request its use:

(i) Measuring the absolute manifold vacuum of a representative vehicle, of the same equivalent inertia weight class, when operated on a level road under balanced wind conditions at a true speed of 50 m.p.h., and

(ii) Noting the dynamometer indicated road load horsepower setting required to reproduce that manifold vacuum, when the same vehicle is operated on the dynamometer at a true speed of 50 m.p.h. The tests on the road and on the dynamometer shall be performed with the same vehicle ambient absolute pressure (usually barometric), i.e. within ±5 mm.-Hg.

(iii) The road load power shall be determined according to the procedure outlined in Appendix B and adjusted according to the following if applicable.

(3) Where it is expected that more than 33 percent of the vehicles in an engine family will be equipped with air conditioning, the road load power listed above or as determined in paragraph 2 of this subsection shall be increased by

10 percent for testing all test vehicles representing such engine family.

(f) The vehicle speed (m.p.h.) as measured from the dynamometer rolls shall be used for all conditions. A speed vs. time recording, as evidence of dynamometer test validity, shall be supplied on request of the Secretary.

(g) Practice runs over the prescribed driving schedule may be performed to find the minimum throttle action to maintain the proper speed-time relationship.

NOTE: When using two-roll dynamometers a truer speed-time trace may be obtained by minimizing the rocking of the vehicle in the rolls. The rocking of the vehicle changes the tire rolling radius on each roll. The rocking may be minimized by restraining the vehicle horizontally (or nearly so) by using a cable and winch.

(h) The drive wheel tires may be inflated up to 45 p.s.i.g. in order to prevent tire damage. The drive wheel tire pressure shall be reported with the test results.

$ 1201.77 Three-speed manual transmissions.

(a) All test conditions except as noted shall be run in highest gear.

(b) Cars equipped with free wheeling or overdrive units shall be tested with this unit (free wheeling or overdrive) locked out of operation.

(c) Idle shall be run with transmission in gear and with clutch disengaged (except first idle; see § 1201.80).

(d) The vehicle shall be driven with minimum throttle movement to maintain the desired speed.

(e) Acceleration modes shall be driven smoothly with the shift speeds as recommended by the manufacturer. If the manufacturer does not recommend shift speeds, the vehicle shall be shifted from first to second gear at 15 m.p.h. and from second to third gear at 25 m.p.h. Each shift should be accomplished rapidly to minimize closed-throttle time. If the vehicle cannot accelerate at the specified rates, the vehicle shall be accelerated at WOT until the vehicle speed reaches the speed at which it should be at that time during the test.

(f) The deceleration modes shall be run with clutch engaged and without shifting gears from the previous mode, using brakes or throttle as necessary to maintain the desired speed. For those

modes which decelerate to zero, the clutch shall be depressed when the speed drops below 15 m.p.h. when engine roughness is evident, or when engine stalling is imminent.

(g) Downshifting is allowed at the beginning of or during a power mode if recommended by the manufacturer or if the engine obviously is lugging.

§ 1201.78

Four-speed and five-speed manual transmissions.

(a) Use the same procedure as for three-speed manual transmissions for shifting from first to second gear and from second to third gear. If the manufacturer does not recommend shift speeds, the vehicle shall be shifted from third to fourth gear at 40 m.p.h. Do not use fifth gear.

(b) If transmission ratio in first gear exceeds 5 1, follow the procedure for three- or four-speed manual transmission vehicles as if the first gear did not exist.

§ 1201.79

Automatic transmissions.

(a) All test conditions shall be run with the transmission in "Drive" (highest gear).

(b) Idle modes shall be run with the transmission in "Drive" and the wheels braked (except first idle; see § 1201.80).

(c) The vehicle shall be driven with minimum throttle movement to maintain the desired speed.

(d) Acceleration modes shall be driven smoothly allowing the transmission to shift automatically through the normal sequence of gears. If the vehicle cannot accelerate at the specified rates, the vehicle shall be accelerated at WOT until the vehicle speed reaches the speed at which it should be at that time during the driving schedule.

(e) The deceleration modes shall be run in gear using brakes or throttle as necessary to maintain the desired speed. § 1201.80 Engine starting and restarting.

(a) The engine shall be started according to the manufacturer's recommended starting procedures including choke setting. The initial 20-second idle period shall begin when the engine starts. (b) Choke operation:

(1) Vehicles equipped with automatic chokes shall be operated according to the manufacturer's operating or owner's manual including "kick-down" from cold

fast idle. If choke "kick-down" time is not specified, it shall be performed 13 seconds after the engine starts. The transmission shall be placed in gear 15 seconds after the engine is started. If necessary, braking may be employed to keep the drive wheels from turning.

(2) Vehicles equipped with manual chokes shall be operated according to the manufacturer's operating or owner's manual. If not specified, the choke shall be operated to maintain engine idle at 1,100 50 r.p.m. during the initial idle period and used where necessary during the remainder of the test to keep the engine running.

(c) The operator may use more choke, more throttle, etc., where necessary to keep the engine running.

(d) If the vehicle does not start after 10 seconds of cranking, cranking shall cease and the reason for failure to start determined. The revolution counter on the constant volume sampler (see § 1201.85, Dynamometer test runs) shall be turned off and the sample solenoid valves placed in the "dump" position, and the positive displacement pump turned off during this diagnostic period. If failure to start is an operational error, the vehicle shall be rescheduled for testing from a cold start. If failure to start is caused by vehicle malfunction, corrective action of less than 30 minutes duration may be taken and the test continued. If corrective action is unsuccessful in 30 minutes, the test shall be aborted. If the test is continued, the sampling system shall be reactivated at the same time cranking is started. When the engine is operating satisfactorily the driving schedule timing sequence shall begin. In all cases in which failure to start is caused by vehicle malfunction and the vehicle cannot be restarted the test shall be considered a valid failed test. The reason for the malfunction (if determined) and the corrective action taken shall be reported with the test results.

(e) If the engine "false starts", the operator shall repeat the recommended starting procedure (such as resetting the choke, etc.).

(f) Stalling:

(1) If the engine stalls during an idle period, the engine shall be restarted immediately and the test continued. If the engine cannot be started soon enough to allow the vehicle to follow the next acceleration as prescribed, the driving schedule indicator shall be stopped.

When the vehicle restarts the driving schedule indicator shall be reactivated.

(2) If the engine stalls during some operating mode other than idle, the driving schedule indicator shall be stopped, the vehicle restarted, accelerated to the speed required at that point in the driving schedule and the test continued.

(3) If the vehicle will not restart within 1 minute, the test shall be aborted and considered a valid failed test.

§ 1201.81 Sampling and analytical system (exhaust emissions).

(a) Schematic drawings. The following figures (Figures 1a and 1b) are schematic drawings of the exhaust gas sampling and analytical systems which will be used for testing under the regulations in this part. Additional components such as instruments, valves, solenoids, and switches may be used to coordinate the functions of the component systems.

(b) Component description (exhaust gas sampling system). The following components will be used in the exhaust gas sampling system for testing under the regulations in this part. See Figure 1a. Other types of constant volume samplers may be used if shown to yield equivalent results.

(1) A dilution air filter assembly consisting of a particulate (paper) filter to remove solid matter from the dilution air and thus increase the life of the charcoal filter; a charcoal filter to reduce and stabilize the background hydrocarbon level; a second particulate filter to remove charcoal particles from the air stream. The filters shall be of sufficient capacity and the duct which carries the dilution air to the point where the exhaust gas is added shall be of sufficient size so that the pressure at the mixing point is less than 3 inches of water pressure below ambient when the constant volume sampler is operating at its maximum flow rate. The dilution air filter assembly is not required when the dilution air hydrocarbon level is below 15 p.p.m. carbon equivalent.

(2) A flexible, leak-tight connector and tube to the vehicle tailpipe. The flexible tubing shall be of sufficient size to limit the inaximum pressure at the tailpipe to less than 5 inches of water pressure above ambient during the test.

(3) A heating system to preheat the heat exchanger to within ±10° F. of its operating temperature before the test begins.

Figure 1b.

N5

N4

Exhaust

(4) A heat exchanger capable of limiting the gas mixture temperature variation during the entire test to +10° F. as measured at a point immediately ahead of the positive displacement pump.

(5) A positive displacement pump to pump the dilute exhaust mixture. The pump capacity (300 to 350 c.f.m. is sufficient for testing most vehicles) shall be a minimum of eight times the average exhaust flow rate of the vehicle being tested. See Appendix C. The purpose of the high dilution is to minimize the possibility of water condensation in the system. High ambient humidity may require

HC CALIBRATING GAS

CO CALIBRATING GAS

PREPURIFIED AIR ZEROING GAS

Gas Analytical System higher dilution rates.

(6) Temperature sensor (T1) with an accuracy of +2° F. to allow continuous recording of the temperature of the dilute exhaust mixture entering the positive displacement pump.

(7) Gauge (G1) with an accuracy of +1 mm. Hg to measure the pressure depression of the dilute exhaust mixture entering the positive displacement pump, relative to atmospheric pressure.

(8) Gauge (G2) with a accuracy of +1 mm. Hg to measure the pressure increase across the positive displacement pump.

(9) Sample probes (S1 and S2) to collect samples from the dilution air stream and the dilute exhaust mixture. The probes shall be pointed upstream and sized so that the gas velocity in the probe inlet is within ±25 percent of the bulk stream velocity. Additional sample probes may be used, for example, to obtain continuous concentration traces of the dilute exhaust stream. In such case the sample flow rate, in standard cubic feet per test, must be added to the calculated dilute exhaust volume. The position of the sample probe in Figure la is pictorial only.

(10) Filters (F1 and F2) to remove particulate matter from dilution air and dilute exhaust samples prior to entering sample collection bags.

(11) Pumps (P1 and P2) to pump the dilution air and dilute exhaust into their respective sample collection bags.

(12) Flow control valves (N1 and N2) to regulate flows to sample collection bags, at constant flow rates. The minimum sample flow shall be 5 c.f.h.

(13) Flowmeters (FL1 and FL2) to insure, by visual observation, that constant flow rates are maintained throughout the test.

(14) Three-way solenoid valves (V1 and V2) to direct sample streams to either their respective bags or overboard.

(15) Quick-connect leak-tight fitting (C1 and C2) with automatic shut-off on bag side to attach sample bags to sample system.

(16) Sample collection bags for dilution air and exhaust samples of sufficient capacity so as not to impede sample flow.

(17) A revolution counter to count the

revolutions of the positive displacement pump while the test is in progress and samples are being collected.

(c) Component description (exhaust gas analytical system). The following components will be used in the exhaust gas analytical system for testing under the regulations in this part. The analytical system provides for the determination of hydrocarbon concentrations by flame ionization detector (FID) analysis and the determination of carbon monoxide concentrations by nondispersive infrared (NDIR) analysis in dilute exhaust samples. See Figure 1b.

(1) Filter (F3) to remove any residual particulate matter from the collected samples.

(2) Pump (P3) to transfer samples from the sample bag to the analyzers.

(3) Selector valves (V3, V4, and V5) for directing sample and calibrating gases or zeroing gas to the analyzers.

(4) Flow control valves (N3, N4, N5, and N6) to regulate flows to a constant rate of 5 c.f.h.

(5) A flame-ionization-detector type analyzer to measure HC concentrations. (6) A carbon monoxide sensitized nondispersive infrared analyzer to measure CO concentrations.

(7) Flowmeter (F3) to indicate sample flow rate.

(8) Recorders to provide permanent records of calibration, spanning and sample measurements.

§ 1201.82 Sampling and analytical system (fuel evaporative emissions). (a) Schematic drawings. (1) The following figures (Figures 2, 3, and 4) are flow diagrams of typical evaporative loss collection applications.