51 votes
Accepted

What is the point of the exhaust?

Safety, comfort, noise and space are the things that come to mind. Safety Exhaust gasses are hot as hell. Hot enough that we put heat shields all over the exhaust line. In engines, we are actively ...
Becuzz's user avatar
  • 666
44 votes

What is the point of the exhaust?

Well, we can have a pipe going out the front of a car as in this design here: or its heavier predecessor: Arguably, the aerodynamic properties are not optimal in both, but here is a similar approach ...
the-wabbit's user avatar
20 votes
Accepted

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

The supplied gas values suggest a rich run condition and possibly a non-functional catalyst. Using a mixture calculator for the supplied gas values shows that the mixture is 6.4% rich. CO elevated ...
Fred Wilson's user avatar
  • 11.6k
14 votes

What is the point of the exhaust?

Several things; Exhaust coming out the front is dangerous. If the fumes are ingested into the cab the driver may be harmed. Normally a car is driven forward. If the exhaust is coming out the back ...
vini_i's user avatar
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13 votes
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How does raw fuel damage the catalytic converter?

A catalyst is a chemical that contributes in a chemical reaction but remains unchanged after the whole reaction is complete. In a catalytic converter platinum is the catalyst that converts unburned ...
BillDOe's user avatar
  • 1,512
9 votes
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What is the "Activated Carbon Cannister"?

Gasoline is a pretty toxic liquid. And it evaporates pretty easily. The Carbon Cannister is a system to help keep toxic fumes from gasoline out of the environment. So here's how it works. You ...
zipzit's user avatar
  • 6,539
9 votes

What is the point of the exhaust?

The exhaust also creates a pressure differential, which can help scavenge exhaust gases from the chamber. So a properly tuned exhaust will therefore increase the fuel efficiency of the engine. Whilst ...
Damien's user avatar
  • 91
7 votes

What is the point of the exhaust?

Adding to the excellent answers already given. An important point to note is that we need to have a catalytic converter somewhere in the exhaust a short exhaust will not have room to fit it. Then ...
Shobin P's user avatar
  • 8,936
7 votes

How are diesel engines better for the environment than gasoline?

Locally worse, globally better Diesel exhaust versus gasoline: about 15-20 % less CO2 about 4-100 times the NOx (highly temperature dependent, mitigated by proper use of diesel exhaust fluid, ref ...
user2394284's user avatar
7 votes
Accepted

Connecting to the Battery During Emissions Testing to Measure RPMs?

The voltage being a little low (13.75 is not low enough to be considered a problem in any case) is not going to affect their RPM reading - as it's the frequency of voltage variations that is measured ...
Rory Alsop's user avatar
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4 votes

EFI engine car failed Emission test?

Before suspecting a bad O2 sensor... You need to be sure that the replacement MAF is suitable for your car. You mention the replacement MAF is a 5-pin and not a 4-pin like the one originally on the ...
Zaid's user avatar
  • 39.1k
4 votes
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Relation of VIN of a car with emission norms of a country it is sold

Cars are manufactured to meet the emission standards of the country it is intended to be sold in. If the car was manufactured in Canada with the intent to be sold in India, it will be designed to meet ...
tlhIngan's user avatar
  • 12.2k
4 votes

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

"Flex Fuel" isn't an issue (I assume you mean E85 and similar) if you use injector duty cycle as the basis of your calculations. Total injector "on" time gives you fuel consumption, regardless of the ...
SteveRacer's user avatar
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4 votes
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What are vehicle emission limitations in Bavaria?

First of all, this doesn't apply to Bavaria alone, but to all Germany. You are right, diesel and petrol cars get the same stickers, though, petrol cars get either no sticker (no catalytic converter, ...
sweber's user avatar
  • 7,057
4 votes

Will eliminating factory catalytic converter have effect on emission testing?

Yeah. With out other illegal cheats you won't pass a real emissions test. There are sensors in your exhaust system that provide feedback to the engine computer. With out your catalytic bricks in place ...
zipzit's user avatar
  • 6,539
4 votes
Accepted

Will eliminating factory catalytic converter have effect on emission testing?

In most places which have emissions testing, not only is there a smog test (where they attach your car to a computer), there's also a visual test. The inspector views to see that all emissions ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
4 votes
Accepted

What is the purpose of secondary air injection?

You're right. The primary purpose of a secondary air injection system is to consume the excess fuel that is injected during cold-start enrichment before it can reach the catalytic converter. This has ...
Zaid's user avatar
  • 39.1k
4 votes

What can cause "check gas cap" warnings other than a loose gas cap?

The evap test system creates a vacuum in the fuel system in order to check for integrity. The cap check light comes on when there is air leak somewhere in your system - it might be tank or cap or ...
AsenM's user avatar
  • 1,187
4 votes

What should I expect as result of a firmware update fixing NOx emissions in a gasoline engine?

If the fix is to keep the oxygen sensors working, in normal operation you won't notice anything. If the sensors were to become unavailable (i.e. a car in an unpatched state) you would see poor ...
Steve Matthews's user avatar
3 votes

What are vehicle emission limitations in Bavaria?

Look again at the page you referred to, you need the second table marked 'Petrol'. According to this page by the German certification authority TUV, you are allowed to drive your Mustang in the ...
Hobbes's user avatar
  • 4,412
3 votes

Smog test fail, lack of oil?

Here are some of the translations for your errors by code P0300 - This random multiple misfires on random cylinders P0301 - Cylinder 1 misfire. You could have a bad spark plug, a bad spark plug wire,...
DucatiKiller's user avatar
  • 32.9k
3 votes
Accepted

What fuel injectors I have to install?

It looks like the California emissions injectors flow more fuel and have a higher resistance. The design also looks different this could lead to fuel leaks. If you had a Federal emissions car it could ...
Ben's user avatar
  • 10.7k
3 votes

What fuel injectors I have to install?

Your car is either a California car or it is not. You can call the dealer and give them your VIN number and in order to have your vehicle identified. Once you know what your car is then you can ...
DucatiKiller's user avatar
  • 32.9k
3 votes

Car loses power while driving very briefly and on hills?

OBD II P0300- Random, Multiple Misfire Detected (Generic Code) Causes:Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable) Incorrect ignition timing Vacuum ...
Old_Fossil's user avatar
  • 3,962
3 votes
Accepted

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

The average gas engine exhausts between 1 and 1.5 CO during normal combustion at stoiciometric mixture (lambda 1.00). The catalysts is expected to burn this excess CO. So if there is .6% at the ...
Fred Wilson's user avatar
  • 11.6k
3 votes

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

The data doesn't support it You measured your coil resistances to be within spec You measured your wire resistances to be within spec You've already replaced the plugs with ones that require less ...
Zaid's user avatar
  • 39.1k
3 votes
Accepted

EFI engine car failed Emission test?

It sounds a lot to me like it could be your car's O2 (lambda) sensor in the exhaust. From wikipedia Oxygen sensor Function of a lambda probe Lambda probes are used to reduce vehicle emissions by ...
Steve Oakes's user avatar
  • 1,096
3 votes

PCV Valve hose question

Yes, you could use any fuel and oil resistant hose. They are typically made of silicone, polyurethane or rubber. This will ensure longevity of the replaced hose. Have a look at silicone automotive ...
DizzyFool's user avatar
  • 1,571
3 votes
Accepted

Emissions - High CO reading only

The Lambda readings are slightly lean but within the acceptable range for normal catalytic converter operation. The CO is in the normal output range for an engine that is running normally and within ...
Fred Wilson's user avatar
  • 11.6k
3 votes

Is this MX-5 running too cold, and could that explain poor emissions?

… the car is running at 85 deg C. Is this still too low? Without getting into MX-5 specifics (for which the model year needs to be known), 85 °C isn't a crazy low value for engine coolant temperature ...
Zaid's user avatar
  • 39.1k

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