Throttle Control System

1. Connect tachometer, then start engine and run until it reaches normal operating temperature.
2. Disconnect vacuum hose from throttle opener on Prelude, or throttle controller on Accord, connect suitable vacuum pump to controller/opener, and draw a vacuum of 8 in. Hg. Engine speed should rise to 1500-2500 RPM.
3. If RPM is too low, widen adjustment slot of controller/opener lever with screwdriver.
4. If RPM is too high, narrow adjusting slot with suitable pliers.
5. If RPM cannot be adjusted or diaphragm will not hold vacuum, replace throttle controller/opener and repeat test.
6. Disconnect vacuum pump and reconnect hose.
7. Raise engine speed to 3500 RPM and maintain for 2-3 seconds.
8. Release throttle suddenly and note time required for throttle controller/opener arm to fully extend. Required time should be 1-4 seconds.
9. If engine speed returns to idle within specifications, proceed to step 17, except for Prelude. On Prelude, test is complete if engine speed returns to idle within specifications.
10. If throttle takes longer than 4 seconds to return, check throttle controller/opener lever for free movement, then replace dash pot check valve and repeat test. If throttle returns in less than 1 second, proceed with step 11.
11. Disconnect hose from throttle controller/opener and attach vacuum gauge to hose.
12. Start engine and run at 4000 RPM. Vacuum should be at least 1.2 in. Hg.
13. If vacuum is at least 1.2 Hg, replace dash pot check valve and repeat test.
14. If vacuum is below 1.2 in. Hg, check for vacuum at carburetor port.
15. If there is no vacuum, clean carburetor port and repeat test.
16. If there is vacuum, check vacuum line for leaks, blockage, or loosen connection and repeat test.
17. Perform cranking solenoid valve test as follows:
a. Ground coil secondary wire, then turn ignition key to start position. Throttle controller arm should retract when engine is cranked.
b. If controller does not operate, check for voltage at cranking solenoid valve.
c. Connect connector and insert positive probe of voltmeter into blue/red wire on Accord models and black/white wire on Prelude models.
d. If there is no voltage, check wiring and fuse. Repair or replace as necessary, then repeat test.
e. If wiring and fuse were satisfactory, replace starter relay.
f. If there was voltage in step c, disconnect hose between cranking solenoid valve and check valve at solenoid valve and check for vacuum while cranking engine.
g. If there is vacuum, replace cranking solenoid valve and repeat test.
h. If there is no vacuum, check vacuum line for leaks or blockage.
i. If vacuum line is satisfactory, replace check valve and repeat test.