Taurus Car Club of America : Ford Taurus Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
64 Posts
Discussion Starter · #1 ·
Hi, I was wondering if someone could give me advice on how to replace my 02 sensors in my 1994 Ford Taurus FI. It has about 90,000 miles on it.

Yesterday I was driving and my check engine light came on and the car started stuttering a little. A few minutes later I was stopped at a light and when I started to go the car refused to accelerate although it did move slowly so I parked it and had AAA tow it back to my house. I did a code read today and got 172 and 176 (continuous memory) which indicate a failed HEGO sensor which I understand to be an 02 sensor. I just looked up the symptoms and they seem to fit (I was also having bad fuel economy before this).

I'm not sure where they are or how to replace them, or where to get them, rock auto maybe? Any advice from someone who has done this before would be really useful.

Thank you,
Rachel
 

·
Super Moderator
Joined
·
8,586 Posts
You problem is not O2 sensors. Those codes mean that the O2 sensors are reporting a rich condition. First thing is to pull the vac hose off the fuel pressure regulator and see if there is gas in the vac line of if the line has a strong gas odor. If so, replace the regulator. If that test passes, check fuel pressure at idle. Should be 39 psi with vac hose off, and low 30s with vac hose on. If that test fails, also replace the regulator. If both those tests pass, try cleaning the MAF.
 

·
Registered
Joined
·
5,820 Posts
The O2 are on the exhaust pipes under the car. They are easy to replace. Just get the correct wrench and remove them and disconnect the wire harness. When installing them add some anti seize.

You can get them from Rock Auto or the local parts store.
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #5 ·
Hi,

I have a couple other questions about the 02 sensors and fuel pressure regulator. I know there's a lot of 02 sensor threads and I'm not trying to beat a dead horse, but I was looking for the sensors and I can't seem to find the rear one. Also, my 2 codes indicate "lean condition" for left and for right, I'm not sure if left is front and right is back. I'm also not sure what a lean condition is versus a rich condition.

I am planning to replace the fuel pressure regulator first since the general consensus seems to be that the codes often indicate a problem with the fuel rather then the 02 sensors themselves, and it seems unlikely that both sensors would fail at the same time. Is the fuel pressure regulator the right thing to replace for a lean condition as well as a rich condition? Any hints on the replacement process? I found a good video on youtube and it looks pretty doable.
 

·
Registered
Joined
·
1,365 Posts
You're making a big mistake buying parts without knowing the problem. You need to take the money you're going to spend on parts and buy an EFI fuel pressure regulator and a scantool that will read your OBD 1 fuel trims. You can't diagnose a car by internet forum consensus.
 

·
Super Moderator
Joined
·
8,586 Posts
^^^^^^ +1

What WJC said. Throwing parts at the car gets expensive real quick, and likely will not solve the problem. You need to systematically troubleshoot the problem. Unfortunately, EEC IV from 1994 doesnt have access to live data, such as fuel trims, from the PCM.

As I said, YOUR PROBLEM IS NOT the O2 sensors, ESPECIALLY if you have codes for BOTH banks. Both O2s dont fail at the same time.
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #8 ·
Ok I'll do more research before I buy parts. I'm going off of this forum, my Hayne's manual and internet research, best I can do at this point. Can't afford those mechanics classes I wanted to take, bummer. I'll research fuel trims and try to put together a troubleshooting process for why my 02 sensors are reporting lean fuel condition. Thanks for the candid help :)
 

·
Premium Member
Joined
·
1,283 Posts
What they said, those codes indicate a rich condition, the computer is attempting to correct, but has reached its maximum adaptive limit. The fuel pressure regulator is something both banks have in common.

You will need to purchase a fuel pressure gauge, and see what is going on with the pressure. Basically you need to see what the pressure is with the key on, engine on, both at idle, and with the vacuum line disconnected from the regulator. Then you need to do it with the key on engine off, and see what the pressure is, then leave it sitting like that for a half hour and see if the pressure drops.

My guess is the regulator is either regulating high, or it is leaking fuel into the vacuum system. The tests will help isolate and diagnose the problem. The procedure should also be found in your Haynes manual.
 

·
Super Moderator
Joined
·
8,586 Posts
As Kahn said (and I said earleir), those codes are RICH codes, not lean codes. Rich condition is generally MUCH easier to diagnose than lean codes. I would suggest fixing it ASAP before the excess fuel in the exhaust fries / plugs / melts down the cats. Replacing those will get REAL expensive.
 

·
Registered
Joined
·
10,559 Posts
Rich

As Kahn said (and I said earleir), those codes are RICH codes, not lean codes. Rich condition is generally MUCH easier to diagnose than lean codes. I would suggest fixing it ASAP before the excess fuel in the exhaust fries / plugs / melts down the cats. Replacing those will get REAL expensive.
Rich can come from mass air flow sensor, and from plugged air filter. Just for the easy ones to check.

-chart-
 

·
Registered
Joined
·
64 Posts
Discussion Starter · #12 ·
Yes! A new gauge! I had so much fun with that engine compression tester you guys taught me how to use last summer it's about time I got something new!

Sorry I kept getting the rich/lean description wrong. I will do diagnostics accordingly and go from there. Perhaps this will explain that gasoline smell under the hood too.
 
1 - 12 of 12 Posts
Top