Emissions and Exhaust Systems

runs rich getting to much gas.check the choke if carburated if FI check fuel pressure

P0499 Evaporative Emission System Vent Control Circuit High

Its a very complex answer. Here's the short version. Millions of years ago plants absorbed energy from the sun. Those plants got buried and time, pressure and heat turned them into fossil fuels. We clean it up, run it through our engines, where with the proper amount of pressure and temperature the fossil fuel will release the energy stored from the sun millions of years ago and create heat.

The process is called combustion. Any hydrocarbon will combust if pressurized (heated) enough. Diesel fuel self ignites when subjected to about 22 to 1 compression. Gas engines assist the initial combustion with a spark plug.

some of the gases are burnt and reduced befor going to the exhaust

I believe the manuals will say 100,000 miles, but I only change them when they generate an error. If your check engine light is on, a DLC reader (Which you can "borrow" from most part stores) will show what errors or registered, and the O2 sensor is a common one on older cars.

1 3/4 inches

Carbon Monoxide is a by-product from burning fuel from cars. The fuel from cars is a petroleum-derived mixture gasoline, when burned, produces energy and waste products, Carbon Monoxide and other gases

There are no differences. High flow catalytic converters are not really high flow; the catalytic converters you have on your vehicle are as high flow as you need them to be.

A "high" flow converter will either be of a larger diameter, or the inside is made in such a way that there is less restriction to exhaust flow.

you should try a top-end engine cleaner, you might have it done by professional for around 80-90 bucks, or do it yourself with a product called Seafoam. You pull a vacuum line from the vehicle while it's running let it pull part of the can into the motor, cut it off and let it sit for 15-20 min and this will soak into the carbon deposits that your seeing exit your tail pipe as a white smoke substance, and upon restarting run the crap out of your car and feel and see the difference!

yes, it's threaded into the front of the front catalytic converter. that's bank 1 sensor 1. (bank 1 sensor 2 is threaded into the rear of the rear catalytic converter. in order for the car (more specifically the computer) to refine how well the engine will run, and also to keep the amount of pollutants headed out the tailpipe down as low as possible [especially carbon monoxide (CO), hydrocarbons (HC), and oxides of nitrogen (NOx)], the computer constantly compares the two (in this case) oxygen sensor readings (while the engine & computer are running "closed loop") and alters/tweaks/maintains fuel, ignition timing, spark, cooling fans, etc., in order to maximize efficiency. i just googled "oxygen sensor info," and this is the first website i saw http://mr2.com/TEXT/O2_Sensor.html ; it might give you a little more background theory about O2 sensors and how they work, in case you're interested. my idea is that if you understand how they work, why they work, and how to test them, you won't throw away money replacing parts that don't need replacing. good luck. The 2000 Subaru Outback has 2 oxygen sensors. One is located at the front of the catatlytic converter, and the second is at the rear of the catalytic converter. My best guess is #1 is at the front, but I'm not positive here. I'm replacing both anyway as I'm at 100K miles. David

It is only necessary when the computer recognizes a problem with it. You will have a check engine code. Mine triggered a code " low output " for about 6 months before I changed it, it was still operating ok and not affecting engine performance but the minor fault was picked up by the computer. Even though there isn't a recommended interval, you should probably look at changing them out about 30-50k miles. You risk excessive wear to other vehicle components so waiting on the engine light to come on is not a very good measure, however this has been recommended in the past. Most O2 sensors pay for themselves within the first year of replacing them just in fuel savings, not to mention what you save on engine and drivetrain wear.

White smoke out the tailpipe is water entering the combustion chamber. In other words either the gasket slipped or was not put on correctly or there is a bad head gasket or a crack in the intake, block or head.

Most likely your head gasket is blown, allowing engine coolant to seep into the combustion chamber and as it burns it burns white. Are you loosing engine coolant with no external leaks.. (no puddles on the ground)? If there isn't any external leaks, and the problem persists, then you need to do a compression test leak down test to verify the problem, and repair it immediately, before there is further damage.

It may have a leaking head gasket. Has the coolant level dropped and needed more antifreeze . If so check it with a pressure tester

Yes. Va will pass your car with a check engine light. The inspection station will try to get you to figure out what is wrong with you car but they will not fail it. However, If your SRS light is on, the car will fail the inspection.

To keep dirt, water, etc out of the fuel tank.

'Well I have a 95 Buick LeSabre, and the check engine light keeps coming on. So I asked a guy at car-x, and he said that usually occurs when you go really slow on the interstate.'

This takes a little effort but it can be done with a volt meter. Typically they measure this with the repair computers in the dealerships and such. For a single wire sensor trace the wire color back into the cars computer. The computer is usually under a seat, passenger side dash or under the console. To make sure you traced the right wire disconnect the o2 sensor and using the connector end (of the wiring harness NOT the o2 sensor)use your meter and "ohm out" the wire ie check connectivity. On the computer side the harness connector will hopefully be the typical molex connectors that you can press your probe into from the outside. (Do not disconnect from the computer it wont start!).

Now that you know which wire into the computer comes from the o2 sensor, reconnect the o2 sensor and warm up your car. You may consider leaving the voltmeter probe in the molex connector before starting if you are concerned about poking around after it is running. In the volts setting (0-2 or 0-5 volts) leave the positive lead in the connector and the negetive lead to ground (usually anything metal connected to the frame). When you first start your car your numbers will be low 0.1-0.3 volts as this is a rich mixture necessary until the car warms up. Once warm expect numbers in the mid to high range. meaning 0.5 to 0.8 volts. If you bounce the throttle you will see a cyclic response from low to high 0.3 then 0.8 or so as the engine emits its exhaust. Consult your specific auto manual for acceptable ranges.

It is usually between 0 an 1 volt with 0 = rich and 1 equal to lean. Your auto manual should give you outputs for idle, and possibly under load (driving at a constant rpm)

If you have a multi wire sensor the same applies but you have to fish out the "signal" wire coming from the sensor. The other wires are typically for heating the sensor.

... I have done it myself on several cars but I don't know what they all look like and behave like so use this only as one data point.

That means your engine is running "rich". Which is to say that you have too much fuel and not enough air being burned in your engines cylinders. Check the fuel pressure regulator, the Mass Air Sensor, the Mass Air Temperature Sensor, the Engine Coolant Temperature Sensor or the EGR valve can be stuck open. The best place to begin is to have the car scanned with a code reader or a scanner. (Autozone does that for free here)

bad o2 sensor on left bank

possible cylinder head fault or head gasket failer, may be valve or valve stem seal failer, easiest way to find out is do a compression test across all four cylinders.

this is also know as dohc this is to make the engine more fuel efficient and also to give a little more kick to the engine when you lay in to it using both valves allow the engine to bring in more gas at high rpms and let out the exhaust the same way these are in the newer engines because with dohc there is less chance for thing to brake and make the engine more powerful then a regular sohc

On a 1998 Lincoln Continental :

firewall

1-----2-----3-----4

5-----6-----7-----8

front of vehicle > driver

a blow piston or a head gasket in your engine

It's a long story so I will elaborate beyond my question a little here.

Repo people have been coming to our house looking for a girl who rented there before us. We keep telling them we have no idea who she is and that we have lived in the house for 7 mos now. This last group of "thugs" came after dark in an unmarked pickup. They were demanding to see in our garage, and one guy said "if you don't let us in, I'm going to come back every night until I see that garage." My husband told them "if you're going to take that attitude, you can go f yourself and get off of my property right now." So the guy said "ok I'll go f myself then" and they left. How do we know if they were legitimate repo people or thieves you know?? Their truck was unmarked and they were a bunch of huge tough guys.

The next morning we went to start the car to run errands and the car made a chugging, rumbling noise and we shut it off immediately. We looked around the car and saw some white smoke coming out of the left rear tailpipe. This car is a 2008 Nissan Altima and has never given us problems before. We called in a police report just to be safe.

I'm wondering if this sounds like a freak coincidence, or if it is possible that one of these guys could have done something to sabotage it during the night. There wasn't any sign of forced entry into the doors, hood or even gas tank, and we couldn't see anything in either of the tailpipes. I don't know what someone could do externally to cause this?

Thanks for your time!