Weird o2 sensors.

[Dylan King]

When i fisrt got my sho id say about half the sensors were bad on the car but i replased them all including the o2 sensors. But every other month or so the sensors would go out. I was useing premium BP gas. I was getting about 13 to 14mpg in the city I know thats not good compared to some of you other guys cars. But thats my next question. Know i use shell. They dont seem to be going out ever since i switched gas companys but know i only get about 11mpg. Is ther a difference in the 2 gases. And could someone give me some kind of list that tells me what could be causeing bad gas mileage. Like what parts do i need to check or clean or replace.

 

[Ishodu]

What is tell you that the O2 sensors are going out?

 

[Dylan King]

The bad gas mileage and the codes from autozone.

 

[SinisterSHO]

The cold weather will also cause bad gas mileage. It causes your car to take longer to warm up and get in the optimal running temp range, at which it runs most efficient.

 

[SHOPWR]

your car is running rich when started and starts to lean up as the engine warms up and idle lowers to normal idle speed.

<small>[ March 05, 2004, 06:44 PM: Message edited by: SHOPWR ]</small>

 

[Ishodu]

Do you know what these codes were? There are code that the o2's can make it dosen't always mean there toast.

 

[Dylan King]

No i dont remember the codes. But i do know they were the codes that indicate bad o2 sensors every time i have it checked.

 

[Mr Anonymous]

Ever think to check to see if your thermostat is stuck open? It's a very common thing to happen with a SHO, it causes the PCM to remain in open-loop mode, with provides a full rich mixture which equals lousy fuel economy.

Go to the three links in my signature and learn how to read your own codes. It can be done with a paper clip or short piece of wire.

I'm willing to bet that AutoZone never clears your codes, and you're looking at really old O2 codes every time you go there. Chances are you've been chucking perfectly good O2's in the trash.

Read your codes yourself, clear them out by removing the jumper while the codes are reading out as specified in the directions (you can do this after reading the codes a couple of times in case it takes you a while to get it right). Then drive around and see what happens. Where does your temp gauge usually get to when the car has been driven a good 20-30 mins?

 

[rangerj]

DK,

When the ECU stores a code regarding a sensor it DOES NOT necessarily mean that the sensor is BAD.

The sensor could be sending good information, for example that you are running rich or lean for too much of the time. The rich or lean condition may be caused by other problems, for example; a lean condition can be caused by a vacuum leak, or a rich condition can be caused by poor spark plugs, failing plug wires, or a clogged air filter, etc.

O-2 sensors are usually good for 50K to 100K miles. They usually fail gradually. They stop switching, that is they switch from rich to lean slower than they should.

If the ECU is not getting any signal it is usually a connection problem, say due to corrosion on the connection, or a wire that has broken, or is shorted to grounded.

So, save yourself some money and frustration and use the codes as a diagnostic tool. Do not assume that a code means that a sensor is bad, but use the code to assist in diagnosing the problem.

There are plenty of posts you can search regarding the sensors and the possibilities regarding any particular code number. Then there is this board and all the experience these folks will share with you in diagnosing a problem.

If you have stored codes tell us what they are, the year of the car, the milage on it, what the symptoms are you are experiencing, what you have tried so for, and anything else you think might help us to help you. rangerj

 

[Dylan King]

My temp gauge is usally around the a or the L. And all ive done is switch gases to try an stop the problem. Is it okay to delete codes and how do you do it with out the scanner?

 

[Dylan King]

Oyea my car is a 1993 atx. Every other month i start getting really bad gas mileage and i can smell gas in the car like i have a leak or something. But i checked for leaks and i dont have any. The promblem stops when ever i change the o2 sensors. Weres the best place and cheaps place to buy a scanner?

 

[Ishodu]

Dylan King:
Oyea my car is a 1993 atx. Every other month i start getting really bad gas mileage and i can smell gas in the car like i have a leak or something. But i checked for leaks and i dont have any. The promblem stops when ever i change the o2 sensors. Weres the best place and cheaps place to buy a scanner?

Please read Mr A's post again. You DO NOT need scanner to read or clear codes.

 

[rangerj]

DK,

The consumer studies on gasolines indicate that BP is the dirtiest gasoline on the U.S. market. Try Shell, Sunoco, Citgo, or other name brand qaulity fuel for starters.

Now for your list!

You smell gas and have poor fuel milage. Those would indicate a rich mixture (fuel air mixture ratio greater than 14.1 to 1). So, first pull the spark plugs and look for the black deposits on the plugs. Pull one plug at a time and the ones that are black will tell you that the cylinder is not burning all of the fuel it gets.

If only one or two cylinders are rich it could be bad plugs, or plug wires, or a leaking injector.

If all the cylinders are rich it could be a weak coil, all bad plugs or the wrong plugs (to cold), or bad plug wires. More possibilities are; a plugged air filter (not enough air), or a fuel regulation problem (regulator), or all the injectors are leaking because they are dirty and not closing (pintel sticking to far open).

Have you checked your fuel pressure?

You have an ATX, is the EGR valve working properly?

Make sure the O-2 sensor connections are not corroded and make sure there are no O-2 sensor wires that are shorted say from the insulation being melted on a hot exhaust. What kind of O-2 sensors are you buying, Bosch?

See the posts on clearing the codes. Clear the codes, then deive the car up to full operating temperature (about 10 minutes), and recheck the codes. Tell us what codes you get.

And stop replacing parts until you can determine what THE problem is. rangerj

 

[Dylan King]

Thanks for the info rangerj. I will check on everything you said. I didnt know BP was the dirtiest gas. And yes my o2 sensors are bosch. Is that good or bad? They have a warrenty form autozone for three to four months. So when i change them every other month its not costing me nothing but the trouble of changing them. Could all of those possible problems be causing bad gas mileage?