Spark Plugs Indicate Lean Condition Help Me Troubleshoot
06-15-2010, 09:02 AM
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Spark Plugs Indicate Lean Condition Help Me Troubleshoot
Hey whats up guys heres the situation,
I drive a 93 Honda Civic hatch with an OBD1 B18A1 motor in it that has been rebuilt by me. Anyways a problem that I have been having for a long time is this. Everytime while driving at part throttle as soon I let of the gas the car backfires. I pull the plugs and they look very lean. (Electrodes look white and porceline is completly white.) I have a fuel pressure gauge installed and the fuel pressure is at 38-40psi during idle.
Do you guys think it would be worthwile to take off the intake manifold with the injectors still attached so that I could see the spray pattern of the injectors. Sometimes the car is also dificult to start.
Things I've checked:
Igntion timing is good
Engine timing is good
Fuel Pressure good
NGK plugs from Autozone 2.99 w/ proper gap
I drive a 93 Honda Civic hatch with an OBD1 B18A1 motor in it that has been rebuilt by me. Anyways a problem that I have been having for a long time is this. Everytime while driving at part throttle as soon I let of the gas the car backfires. I pull the plugs and they look very lean. (Electrodes look white and porceline is completly white.) I have a fuel pressure gauge installed and the fuel pressure is at 38-40psi during idle.
Do you guys think it would be worthwile to take off the intake manifold with the injectors still attached so that I could see the spray pattern of the injectors. Sometimes the car is also dificult to start.
Things I've checked:
Igntion timing is good
Engine timing is good
Fuel Pressure good
NGK plugs from Autozone 2.99 w/ proper gap
06-15-2010, 09:43 AM
#3
Re: Spark Plugs Indicate Lean Condition Help Me Troubleshoot
Backfiring indicates unburned fuel in the cylinders. Did you check the ignition timing with the service connector jumped? What conditions are the plug wires, cap, and rotor?
06-15-2010, 11:57 AM
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Re: Spark Plugs Indicate Lean Condition Help Me Troubleshoot
Plug wires were replaced about 3 months ago with oem plug wires. Cap and rotor are in relative good condition.
Yes you're right backfire does indicate unburned fuel. I was thinking with a poor spray pattern from the injectors there would be poor atomazation or mixing of the fuel rusulting in a lean condition. Later, that exess fuel that never got mixed well would then ignite later in the exhaust stream which causes the backfire. I dont know for sure just a hunch. bump
Yes you're right backfire does indicate unburned fuel. I was thinking with a poor spray pattern from the injectors there would be poor atomazation or mixing of the fuel rusulting in a lean condition. Later, that exess fuel that never got mixed well would then ignite later in the exhaust stream which causes the backfire. I dont know for sure just a hunch. bump
06-15-2010, 12:01 PM
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Re: Spark Plugs Indicate Lean Condition Help Me Troubleshoot
06-15-2010, 03:18 PM
#7
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Re: Spark Plugs Indicate Lean Condition Help Me Troubleshoot
if its runing excessivly lean it can create hot spots and lead to detonation and backfires have you checked map ect sensor and O2 sensor ? all effect air/fuel ratio
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06-15-2010, 03:21 PM
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Re: Spark Plugs Indicate Lean Condition Help Me Troubleshoot
no havent checked the map. If I dont have a check engine light doesnt that mean the sensor is working fine?
Last edited by averyvm; 06-16-2010 at 05:40 AM.
06-16-2010, 02:41 PM
#11
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