FAQ: How to Troubleshoot, Repair & Maintain Hondas and Selected Other Vehicles

RickJ · Dec 4, 2006, 09:16 AM

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TxGreaseMonkey · Feb 20, 2007, 09:54 AM

19. Tips to Improve Gas Mileage

1. Check for Diagnostic Trouble Codes.

2. Replace the oxygen sensor. A bad oxygen sensor can radically affect gas mileage, since it controls fuel injector duration. It's best to use the exact brand that came in the vehicle.

3. Go over the whole ignition system. Replace, for example, spark plugs (with exact brand and plug number that came in the vehicle), spark plug wires, rotor, and distributor cap. Replace platinum plugs at half the recommended mileage.

4. Check idle rpm and engine timing.

5. Replace air filter and fuel filter. A new air filter alone can improve gas mileage by as much as 10%.

6. Clean Mass Air Flow (MAF) Sensor, if so equipped, with CRC MAF Sensor Cleaner. Gas mileage and performance can improve markedly.

7. Replace the Engine Coolant Temperature (ECT) Sensor, which affects fuel injector pulse width. The ECT Sensor is a temperature dependant resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot. They become corroded, due to not changing the coolant frequently enough, flood the engine, and waste a tremendous amount of fuel.

8. Check tire pressure. You can lose up to 6% of fuel efficiency for every pound per square inch (psi) below the manufacturer's minimum recommendation.

9. Add Shell Regane or Chevron Techron fuel injector cleaner to gas tank every 6 months. This will clean fuel injectors, throttle body, valves, and combustion chamber.

10. Use full-synthetic lubricants; e.g., engine oil, manual synchromesh transmission fluid, automatic transmission fluid, power steering fluid, differential fluid, and wheel bearing grease. This should easily increase gas mileage 8 to 10%.

11. Check for dragging brakes, including emergency brake.

12. Replace faulty gas cap.

13. Remove excess weight. Remove unused luggage, bicycle or ski racks and other extra weight you may have in your car. Every 200 pounds of unnecessary weight reduces mileage by one mile per gallon.

14. Check alignment.

15. Turn off the air conditioner whenever you can. Running your A/C causes extra work for the engine, which lowers fuel efficiency by 5-10%.

16. Reduce speed--don't exceed 60 mph (96 kph). On the highway, more than 50 percent of the energy required to keep rolling is aimed at overcoming aerodynamic drag. As the pedal hits the metal, the aerodynamic drag and rolling resistance increase. That's why the 55-mph speed limit was clamped on the highways in the '70s. Above 55 mph, fuel economy takes a dive. So, by cutting highway cruising speeds to 65 mph instead of 70 mph, gas is conserved. When you use overdrive gearing, the engine speed decreases, reducing both fuel consumption and engine wear. On the open highway, cruise control maintains a constant speed and can also help reduce fuel consumption.

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TxGreaseMonkey · Mar 14, 2007, 05:58 PM

40. Engine Knock

Soon after I bought my new 1993 Civic DX, I started experiencing serious engine knock. In fact, I was totally disgusted with Honda for designing an engine that was supposed to run on 87 octane fuel and yet exhibited such bad knock. For some time, I thought I would destroy the engine--I almost didn't care. How this engine (D15B7) passed Japanese quality control and system testing escaped me. I tried retarding the timing, which helped somewhat. I knew this was not a very good solution, however. I also tried filling the gas tank halfway with higher octane gas, every other tankful. The situation continued to get worse, particularly in Texas summers with the air conditioner on.

I knew the problem was heat-related, since I didn't have the problem during winter. The situation improved somewhat, when I installed colder running NGK ZFR6F-11 spark plugs, rather than the standard NGK ZFR5F-11 plugs. Part of the problem was that the cooling system only holds .92 gallons of coolant, providing minimal heat sink. Just before installing a 180 degree thermostat, I decided to go to an even colder running plug, which Honda did not even recommend. Engine knock finally disappeared, when I installed NGK ZFR7F-11 plugs (Honda Part No. 98079-5714G). Performance improved and gas mileage was unaffected by the change. Therefore, try this simple solution to engine knock, before taking more drastic measures.

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TxGreaseMonkey · Mar 15, 2007, 10:04 PM

6. Honda OBD-II Diagnostic Trouble Codes (1996 and Later)

Plug scan tool into Data Link Connector (DLC), turn ignition to ON, and read code.

P0106--MAP Circuit Range Or Performance
P0107--MAP Circuit Low Input
P0108--MAP Circuit High Input
P0111--IAT Sensor Circuit Range/Performance
P0112--IAT Sensor Circuit Low Input
P0113--IAT Sensor Circuit High Input
P0116--ECT Circuit Range Or Performance
P0117--ECT Circuit Low Input
P0118--ECT Circuit High Input
P0122--TP Sensor Circuit Low Input
P0123--TP Sensor Circuit High Input
P0131--Primary HO2S Circuit Low Voltage (Sensor 1)
P0132--Primary HO2S Circuit High Voltage (Sensor 1)
P0133--Primary HO2S Circuit Slow Response (Sensor 1)
P0135--Front HO2S Heater Circuit Fault (Sensor 1)
P0137--Secondary HO2S Circuit Low Voltage (Sensor 2)
P0138--Secondary HO2S Circuit High Voltage (Sensor 2)
P0139--Secondary HO2S Circuit Slow Response (Sensor 2)
P0141--Secondary HO2S Heater Circuit Fault (Sensor 2)
P0171--System Too Lean
P0172--System Too Rich
P0300--Random Misfire
P0301--Misfire Cyl. 1 Or Random Misfire
P0302--Misfire Cyl. 2 Or Random Misfire
P0303--Misfire Cyl. 3 Or Random Misfire
P0304--Misfire Cyl. 4 Or Random Misfire
P0305--Misfire Cyl. 5 Or Random Misfire
P0306--Misfire Cyl. 6 Or Random Misfire
P0325--KS Circuit Malfunction
P0335--CKP Sensor Circuit Low Input
P0336--CKP Sensor Range/Performance
P0401--EGR Insufficient Flow Detected
P0420--Catalyst System Efficiency Below Threshold
P0441--EVAP Emission Control System Improper Purge Flow
P0451--Fuel Tank Pressure Sensor Range/Performance
P0452--Fuel Tank Pressure Sensor Circuit Low Input
P0453--Fuel Tank Pressure Sensor Circuit High Input
P0500--VSS Circuit Malfunction (M/T)
P0501--VSS Circuit Range/Performance (A/T)
P0505--ICS Malfunction
P0560--Powertrain Control Module (PCM) Backup Voltage Circuit Low Voltage
P0700--A/T Concerns
P0720--A/T Concerns
P0725--A/T Concerns
P0730--A/T Concerns
P0740--A/T Concerns
P0753--A/T Concerns
P0758--A/T Concerns
P0763--A/T Concerns
P0780--A/T Concerns
P1106--BARO Circuit Range/Performance
P1107--BARO Circuit Low Input
P1108--BARO Circuit High Input
P1121--Throttle Position Lower Than Expected
P1122--Throttle Position Higher Than Expected
P1128--MAP Lower Than Expected
P1129--MAP Higher Than Expected
P1149--Primary HO2S (Sensor 1) Circuit Range/Performance Problem
P1162--Primary HO2S (No. 1) Circuit Malfunction
P1163--Primary HO2S (No. 1) Circuit Slow Response
P1164--Primary HO2S (No. 1) Circuit Range/Performance
P1165--Primary HO2S (No. 1) Circuit Range/Performance
P1166--Primary HO2S (No. 1) Heater System Electrical
P1167--Primary HO2S (No. 1) Heater System
P1168--Primary HO2S (No. 1) LABEL Low Input
P1169--Primary HO2S (No. 1) LABEL High Input
P1253--VTEC System Malfunction
P1257--VTEC System Malfunction
P1258--VTEC System Malfunction
P1259--VTEC System Malfunction
P1297--Electrical Load Detector Circuit Low Input
P1298--Electrical Load Detector Circuit High Input
P1300--Multiple Cylinder Misfire Detected
P1336--CSF Sensor Intermittent Interruption
P1337--CSF Sensor No Signal
P1359--CKP/TDC Sensor Connector Disconnection
P1361--TDC Sensor Intermittent Interruption
P1362--TDC Sensor No Signal
P1366--TDC Sensor No. 2 Intermittent Interruption
P1367--TDC Sensor No 2 Signal
P1381--Cylinder Position Sensor Intermittent Interruption
P1382--Cylinder Position Sensor No Signal
P1456--EVAP Emission Control System Leak Detected (Fuel Tank System)
P1457--EVAP Emission Control System Leak Detected (Control Canister System)
P1459--EVAP Emission Purge Flow Switch Malfunction
P1486--Thermostat Range/Performance Problem
P1491--EGR Valve Lift Insufficient Detected
P1498--EGR Valve Lift Sensor High Voltage
P1508--IAC Valve Circuit Failure
P1509--IAC Valve Circuit Failure
P1519--Idle Air Control Valve Circuit Failure
P1607--ECM/PCM Internal Circuit Failure A
P1655--SEAF/SEFA/TMA/TMB Signal Line Failure
P1660--A/T FI Signal A Circuit Failure
P1676--FPTDR Signal Line Failure
P1678--FPTDR Signal Line Failure
P1681--A/T FI Signal A Low Input
P1682--A/T FI Signal A High Input
P1686--A/T FI Signal B Low Input
P1687--A/T FI Signal B High Input
P1705--A/T Concerns
P1706--A/T Concerns
P1738--A/T Concerns
P1739--A/T Concerns
P1753--A/T Concerns
P1758--A/T Concerns
P1768--A/T Concerns
P1773--A/T Concerns
P1785--A/T Concerns
P1786--A/T Concerns
P1790--A/T Concerns
P1791--A/T Concerns
P1792--A/T Concerns
P1793--A/T Concerns
P1794--A/T Concerns
P1870--A/T Concerns
P1873--A/T Concerns
P1879--A/T Concerns
P1885--A/T Concerns
P1886--A/T Concerns
P1888--A/T Concerns
P1890--A/T Concerns
P1891--A/T Concerns

OBD-II Code Definitions

Example:
P 0 1 0 1
1 2 3 4 5

1st digit
P = powertrain
B = Body
C = Chassis

2nd digit
0 = Standard
1 = Manufacturer specific

3rd digit
1 = Emission management
2 = Injector circuit
3 = Ignition
4 = Auxiliary emission
5 = Vehicle speed & idle control
6 = Computer & output circuit
7 = Transmission

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TxGreaseMonkey · Mar 24, 2007, 11:42 AM

41. Battery Acid Damage

Few things can slowly and surely do as much damage to your car as battery acid. The results can be catastrophic; i.e., under-hood fuse/relay boxes, wiring harnesses, air conditioning hoses, power steering units, half axles, and battery trays can be ruined. One way to help prevent this is to not overfill batteries. If you do, acid mist will start to cover surrounding components, when the alternator charges the battery. Another way to help prevent battery acid damage is to make a battery cover. Take a plastic milk jug, cut a hole for the negative battery terminal, and size to fit half the battery. This will help protect the under-hood fuse/relay box on many Civics, which cost around $250, from battery acid. It will also help protect key wiring harnesses and air conditioning components from acid. Finally, I recommend removing the battery from the car every 6 months. During this time, wash the battery, check water levels, and inspect the car for acid damage. It helps to have a spray bottle of baking soda and water handy for problem areas.

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TxGreaseMonkey · Apr 5, 2007, 05:33 PM

17. Fuel Pressure Regulator Test

The fuel pressure regulator maintains a constant fuel pressure to the fuel injectors. When the difference between the fuel pressure and manifold pressure exceeds 43 psi, the diaphragm is pushed upward, and the excess fuel is fed back into the fuel tank through the return line.

Test:

1. Attach fuel pressure gauge to service port of fuel filter. Pressure should be 40-47 psi, with fuel pressure regulator vacuum hose disconnected and pinched.

2. Reconnect vacuum hose to fuel pressure regulator.

3. Check that fuel pressure rises when vacuum hose from fuel pressure regulator is disconnected again. If fuel pressure did not rise, replace fuel pressure regulator.

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TxGreaseMonkey · Apr 6, 2007, 01:21 PM

20. Main Relay Harness Tests

If you know the main relay is good, hopefully because you replaced it after 120,000 miles or 10 years, whichever came first, but it still doesn't operate properly, the main relay harness needs to be inspected. Here's how to do it on many Honda 7-P relays:

1. Disconnect main relay connector. Check for continuity between BLK Terminal 2 and body ground. If there isn't continuity, repair an open in BLK wire between the main relay and the main ECM ground, located on the thermostat housing. If there is continuity, then:

2. Measure voltage between YEL/WHT Terminal 1 and body ground. If there isn't battery voltage, replace the ECM (15 A) fuse in the under-hood fuse box or repair an open in the YEL/WHT wire between the main relay and the ECM fuse. If there is battery voltage, then:

3. Turn the ignition switch to ON and measure voltage between BLK/YEL Terminal 5 and body ground. If there isn't battery voltage, then replace ACG (ALT) (S) (15 A) fuse in the under-dash fuse box or repair an open in the BLK/YEL wire between the main relay and the ACG (ALT) (S) (15 A) fuse. If there is battery voltage, then:

4. Turn the ignition switch to START. For manual transmissions, the clutch pedal must be depressed; for automatic transmissions, the gear selector must be in Neutral or Park. Measure voltage between BLU/WHT Terminal 6 and body ground. If there isn't battery voltage, replace STARTER SIGNAL (7.5 A) fuse in the under-dash fuse box or repair an open in the BLU/WHT wire between the main relay and the STARTER SIGNAL (7.5 A) fuse. If there is battery voltage, turn the ignition switch OFF, then:

5. Disconnect the negative battery cable. Next, disconnect the "A" connector from the ECM and check for continuity between GRN/YEL Terminal 8 and Terminals A7, A8. If there isn't continuity, repair an open in the GRN/YEL wire between ECM (A7, A8) and the main relay.

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TxGreaseMonkey · Jun 26, 2007, 07:18 AM

29. Combination Light Switch Replacement

1. Disconnect negative battery cable.

2. Remove lower dashboard cover (3 screws).

3. Remove upper and lower steering column covers (3 screws).

4. Disconnect 4-P and 7-P connectors from combination light switch, remove both screws, and lift out switch.

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