Questions tagged [emissions]

The various chemicals emitted in exhaust gasses from an internal combustion engine. The usual gasses which are measured through emissions testing are Nitrogen Oxide (NO2), Carbon Monoxide (CO2), and HydroCarbons (HC).

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37
votes
3answers
338k views

What does a water like drop coming out of the exhaust of the car signify?

Sometimes while driving in the traffic, I come across a car or two which would be dripping water-like drop from it's exhaust steadily in a break of 4-5 seconds. I tried to ask a couple of people at ...
5
votes
1answer
12k views

How to determine if P0430 is O2 or catalytic converter

2009 CTS4 3.6L P0430 catalyst below efficiency bank 2 comes on periodically. (There are no other codes being thrown.) I put a data logger on it today on my drive to work and the rear sensor is ...
7
votes
3answers
11k views

Emissions - High CO reading only

My 1999 Honda CRV has just failed it's UK MOT test on emissions. Results are below: 1st test: CO 0.73 (FAIL - max is 0.30) HC 78 (PASS - max is 200) Lambda 1.008 (PASS - between 0.970 & ...
2
votes
2answers
863 views

Difference between fuel injectors and emissions standards

I have a 2004 Honda Accord EX Sedan with a 2.4L I-4 with California emissions and 250k miles on it. I desperately need to replace my fuel injectors but the price is steep! Can someone explain to me ...
11
votes
3answers
8k views

What could cause high HC and CO, but low NO and CO2 in a smog test

Despite my confidence in having a (relatively) new catalytic converter and a new O2 sensor, my lovely 1994 BMW 325i Convertible got flagged as a "Gross Polluter." The test results are summarized below:...
32
votes
7answers
9k views

What is the point of the exhaust?

I was thinking today, what is the actual point of an exhaust? Why can't we just have a pipe going out the front of a car instead of taking all the gases to the back of the car? I can only see ...
11
votes
3answers
14k views

Why don't all diesel engines have throttle plates?

I learned recently that many older and some newer diesels don't have throttle plates to control airflow. I was also quite shocked to learn about a condition called diesel engine runaway. Apparently ...
5
votes
1answer
627 views

How to calculate fuel consumption and CO2 emission on flex fuel cars using OBDII data?

Here is the thing: I'm trying to estimate the fuel consumption of cars using OBDII data. It's quite simple if we can treat each fuel and its stoichiometric air fuel ratio separately, but when it turns ...
4
votes
2answers
483 views

Evaporator canister purge system advice needed

1995 Blazer - 4.3 L Vortec V6 CMFI (vin W w/ PCM) 230,000 miles There are no trouble codes. This is a OBD-I or 1.5 system from a GM transitional year (I have the OBD-II style connector). I have ...
8
votes
1answer
4k views

What is the “Activated Carbon Cannister”?

Why do I have an "Activated Carbon Cannister" in my unleaded/petrol car? What is it's purpose? How does it work? Do I need to do anything to maintain it? I would like a general answer, but my car ...
5
votes
4answers
1k views

Emissions Problem: Lambda AND CO Slightly High on my 98 Mazda 626

I just took my 98 Mazda 626 for it's inspection and they said the carbon monoxide is slightly high. The test is done using a tail pipe gas analyzer while holding the RPMs between 2500 - 2800 for ...
1
vote
1answer
3k views

GM P0420 Code - Eliminating Possible Causes in Chevy G10

I have a 1996 Chevy G10 van with 14X,XXX miles on it. It has the 5.0 engine. I do not have a scanner myself, but, according to a shop, the van was throwing code P0420. According to my research, this ...
1
vote
3answers
113 views

What is exhaust gas recirculation?

From what I understand, EGR is used to reduce the temperature of combustion without increasing the amount of fuel injected to reduce NOx emission. This is done by reducing the oxygen percentage ...