Show Posts
1
General Topics / HELP! Failed CA smog with High NOx and HC numbers
« on: March 12, 2013, 04:14:20 PM »
Hi Folks,
My first post here. I own a all stock 1991 318i with 113K miles on it and yesterday I failed smog with high HC and NOx numbers in the 15mph category. Everything else, i.e. CO, was within the acceptable range for the 15mph. In the the 25mph, all the numbers were low and acceptable. What could be wrong? Here is a history of what I have replaced:
- Cat was replaced Summer last year (107Kmiles then)
- Spark plugs replaced Summer last year
- Mess under the intake done Summer last year
- temperature sensors replaced Summer last year
- CPS replaced last year
- Fuel pump and FPR replaced last year
- Air filter and fuel filter replaced last year
-ICV cleaned Summer last year
Here is what wasn't replaced:
- Ignition wires
- Ignition coils
- O2 sensor
- AFM boot
The car passed smog with flying colors exactly a year ago to this day!!! But yesterday it failed. Prior to the test, I noticed that it idles funny. What do I mean? Well when I turn the car on, it idles at 600rpm and then goes up to 1000rpm before coming back down. and it does that forever, regardless of whether the engine is hot or cold. Is this a bad ICV or an intake leak? How do I test it?
Is high NOx and HC an indicator of a misfire? Are my ignition wires and/or coils done and need to be replaced? Is my oxygen sensor gone and need to be replaced? Where do I start?
Thanks for your help gentlemen!
My first post here. I own a all stock 1991 318i with 113K miles on it and yesterday I failed smog with high HC and NOx numbers in the 15mph category. Everything else, i.e. CO, was within the acceptable range for the 15mph. In the the 25mph, all the numbers were low and acceptable. What could be wrong? Here is a history of what I have replaced:
- Cat was replaced Summer last year (107Kmiles then)
- Spark plugs replaced Summer last year
- Mess under the intake done Summer last year
- temperature sensors replaced Summer last year
- CPS replaced last year
- Fuel pump and FPR replaced last year
- Air filter and fuel filter replaced last year
-ICV cleaned Summer last year
Here is what wasn't replaced:
- Ignition wires
- Ignition coils
- O2 sensor
- AFM boot
The car passed smog with flying colors exactly a year ago to this day!!! But yesterday it failed. Prior to the test, I noticed that it idles funny. What do I mean? Well when I turn the car on, it idles at 600rpm and then goes up to 1000rpm before coming back down. and it does that forever, regardless of whether the engine is hot or cold. Is this a bad ICV or an intake leak? How do I test it?
Is high NOx and HC an indicator of a misfire? Are my ignition wires and/or coils done and need to be replaced? Is my oxygen sensor gone and need to be replaced? Where do I start?
Thanks for your help gentlemen!