Hi,
My car (1990 240sx KA24e) got the following results from the emissions test:
My car passed NOx (had 546, with 1258 allowed)It failed HC (183 with 174 allowed) and CO (4.47 with 1.12 allowed)
Can you tell me what this means?
Also, I think the ecu is throwing a code, what do I need to do to check what it is?
Thanks.
Failed emissions, what do I need to fix?
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mattdesmond
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Magnes
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- Car: '89 240SX, done up with a chrome-plated ground wire to the engine.
I'll take a stab at this one.
Sounds like you have incomplete combustion taking place, which could mean a lot of things. Can probably eliminate the possibility that you're running lean though.
First thing is check out the ECU codes, and do a preliminary check of the vacuum hoses and ignition system, including timing.
The ECU codes are read off the ecu itself, you have to pull it out from under the passenger side kick panel. On the opposite side from where the wires are connected there are 2 LEDs and a selector knob. The knob allows you to cycle through 5 different diagnostic modes, the LEDs relay the diagnostic info.
With the ECU out and the engine warmed up, turn the selector clockwise until the LEDs flash 3 times then turn it back the other way (that puts you in diagnostic mode 3). The red LED will flash a number of times followed by the green one. Count the number of flashes, if you get 2 red and 1 green flash, that gives you code 21. There may be several codes stored in memory so keep counting the flashes until they repeat themselves. If you get code 55 it means there are no trouble codes stored.
Caution: Don't select mode 4 at all unless you wish to delete from memory the stored codes.
Get back to us once you have done all the above.
Sounds like you have incomplete combustion taking place, which could mean a lot of things. Can probably eliminate the possibility that you're running lean though.
First thing is check out the ECU codes, and do a preliminary check of the vacuum hoses and ignition system, including timing.
The ECU codes are read off the ecu itself, you have to pull it out from under the passenger side kick panel. On the opposite side from where the wires are connected there are 2 LEDs and a selector knob. The knob allows you to cycle through 5 different diagnostic modes, the LEDs relay the diagnostic info.
With the ECU out and the engine warmed up, turn the selector clockwise until the LEDs flash 3 times then turn it back the other way (that puts you in diagnostic mode 3). The red LED will flash a number of times followed by the green one. Count the number of flashes, if you get 2 red and 1 green flash, that gives you code 21. There may be several codes stored in memory so keep counting the flashes until they repeat themselves. If you get code 55 it means there are no trouble codes stored.
Caution: Don't select mode 4 at all unless you wish to delete from memory the stored codes.
Get back to us once you have done all the above.
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mattdesmond
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OK, I changed the plugs, and it runs a little better. I also checked the ecu via your instructions (thanks!) and First I got a code 33 and then I think it reset, because it gave me a 55 after I tried again. Can I check the timing without special tools? Sorry for all of the questions, but I don't have a factory manual, or even the owners manual.
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mattdesmond
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Magnes
- Posts: 101
- Joined: Thu Jan 30, 2003 6:58 pm
- Car: '89 240SX, done up with a chrome-plated ground wire to the engine.
Probably.
You can check that the O2 sensor is functioning by driving the car while in diagnostic mode I or II. Once the engine is warm (in closed-loop operation) the green light should flash on and off at at least 5 times/second. The more it flashes the healthier your O2 sensor is.
If there is no flashing you might have a bad connection to the O2 sensor. If there is an ongoing problem with the sensor you should get code 33 again on the ECU shortly.
I can't tell you if the O2 sensor is fully responsible for your test results, maybe wait for NISTECH to give his advice, he's the emissions guru. It kinda makes sense that with no O2 sensor operation you would run rich and get the test results you got.
What's your fuel consumption like?
You can check that the O2 sensor is functioning by driving the car while in diagnostic mode I or II. Once the engine is warm (in closed-loop operation) the green light should flash on and off at at least 5 times/second. The more it flashes the healthier your O2 sensor is.
If there is no flashing you might have a bad connection to the O2 sensor. If there is an ongoing problem with the sensor you should get code 33 again on the ECU shortly.
I can't tell you if the O2 sensor is fully responsible for your test results, maybe wait for NISTECH to give his advice, he's the emissions guru. It kinda makes sense that with no O2 sensor operation you would run rich and get the test results you got.
What's your fuel consumption like?
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mattdesmond
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Ok correction needs to be made. It appears complete combustion is really not the problem BUT it has way to much fuel to have complete combustion. with a CO reading of 4.47 % you are just dumping fuel in that engine. since you have an O2 code definitly replace it. If it is bias lean the ECM is trying to compensate by dumping fuel in the cyl's causeing the tremandous rich condition your results show. fix that and have it retested. Be aware though if you correct the rich condition dont be suprised if you then fail for NOx. The reason if you NOx emissions controls are not working right now you wont know it because the rich fuel condition is cooling the cyl so the heat conditions required to merge O2 molocules with Nitrogen molocules is not present. Once you get rid of the coolant[excess fuel] You cyl now has the opertunity to create the heat needed to do it.
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mattdesmond
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