1988 honda accord failed NoX
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1988 honda accord failed NoX
Hi all,
I have a 1988 honda accord lx that recently failed while in cruse mode Nox portion part of the test. The Nox passed at idle. The O2 is exceptionally low telling me the catalitic converter is doing a great job. The HC and CO are also low and passed the part of the test. This tells me that the cat is working fine.
The concern is the Nox at 400 points above maximum it needs to be corrected. Now I have been a state cirtified emissions specialist 10 years ago so started to do test on the EGR valve. Without removing the unit applied a vacume to it..the vacume heald steady. Also heard the pop sound of the valve. Lastly checked to see if the vacume is working going to the unit. It hold 24 inches at idle. I have not opened up the egr valve or tube for inspection. At a engine load car in drive mode and brakes on excelerate the engine it drops off to close to 3 inches? this obviosly is not real world driving so dont consider it accurate.
I have not checked the spark advance. This would be a potentinal problem on these cars? The timming has never been adjusted to the best of my knowledge. Water tempature seems to be fine the gage never gets over 1/2 on the scale and never loose any water that would cause a over heat and a resulting magic 2400 degree F in the cylinders to create the nox.
Read that a vacume leak would cause this problem. The engine at idle and in nutural seems to be very smooth very slight vibration in the stearing. Car has 288km on the engine. So indications of a leak are not probable but would not rule it out. BTW I used propane in the past to detect air leaks in the vacume system is this still the best way to check?
Anything else would be helpfull.
Ohh spark plugs been replaced the wires are fairly new and new air filter. I also sprayed carb cleaner down the barrel of the carb to remove any soot blocking the metering ports.
Any other ideas would be helpfull. After this message I will remove the egr for visual inspection.
Harry
I have a 1988 honda accord lx that recently failed while in cruse mode Nox portion part of the test. The Nox passed at idle. The O2 is exceptionally low telling me the catalitic converter is doing a great job. The HC and CO are also low and passed the part of the test. This tells me that the cat is working fine.
The concern is the Nox at 400 points above maximum it needs to be corrected. Now I have been a state cirtified emissions specialist 10 years ago so started to do test on the EGR valve. Without removing the unit applied a vacume to it..the vacume heald steady. Also heard the pop sound of the valve. Lastly checked to see if the vacume is working going to the unit. It hold 24 inches at idle. I have not opened up the egr valve or tube for inspection. At a engine load car in drive mode and brakes on excelerate the engine it drops off to close to 3 inches? this obviosly is not real world driving so dont consider it accurate.
I have not checked the spark advance. This would be a potentinal problem on these cars? The timming has never been adjusted to the best of my knowledge. Water tempature seems to be fine the gage never gets over 1/2 on the scale and never loose any water that would cause a over heat and a resulting magic 2400 degree F in the cylinders to create the nox.
Read that a vacume leak would cause this problem. The engine at idle and in nutural seems to be very smooth very slight vibration in the stearing. Car has 288km on the engine. So indications of a leak are not probable but would not rule it out. BTW I used propane in the past to detect air leaks in the vacume system is this still the best way to check?
Anything else would be helpfull.
Ohh spark plugs been replaced the wires are fairly new and new air filter. I also sprayed carb cleaner down the barrel of the carb to remove any soot blocking the metering ports.
Any other ideas would be helpfull. After this message I will remove the egr for visual inspection.
Harry
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Joined: Jun 2005
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EGR function is where I would start. If you apply direct vacuum to the EGR valve the car should stall. I would also check for vacuum leaks. The absolute best way to check for leaks is with a smoke machine. A smoke machine pushes smoke created from a special wax heated with a heating element at roughly 1 psi. I swear by them as the best way to find an intake/exhaust/evap etc leak.