O2 sensor Removal

[flexdog]

I am haveing terrible gas milage on on 4.0 V6 1991 eddie bauer

Thought about changing the o2 sensor and got under their and tried to get at it but can't some to get a good grip on the sucker. should I use a crow's foot or some thing the 4 whell drive is in the way.

Also once I get it out where does the wire end plug into seems like it is all the way in the back of the motor near the firewall but i can't see it.

thanks

 

[DeRocha]

The wire harness plugs in the back of the motor and can easily be reached by going through the wheel well (remove the wheel for added clearance.). Most autoparts stores will have a special 02 socket removal tool as a free loaner tool.

 

[410Fortune]

Why change out your 02 sensor?
Is the check engine light on?
If the CEL is not on then skip the 02 sensor or any other emissions sensor

Check engine light is on then pull the code(s)
Throwing new sensors at it will not fix your problem


You need to test your fuel pressure, I have $$$ on your fuel pressure regulator being bad.....

try a search for the pressure regulator, or FPR


You may also want to clean your MAS

How long has it been since the 91 had a tune up?

 

[flexdog]

I got this explorer two months ago and the previous owner rarely drove it
1991 130,000 miles
I got a code 41 off of the scanner
I got a little money right now so I went ahead and bought new 02, fuel filter, plugs, patched a hole in the exhuast, cleaned thotle body, replaced air filter.

got half of the plugs in, drivers side looks like i will half to got through the wheel well for the other half.

I wanted to do all of this before I took it in for a tune up condidering they would probally do it all any way and charge me more for something i could do myself.

What is the normal price for a tune up at say Precision Tune for the engine?

 

[410Fortune]

your half way there

I suggest a fuel filter, clean the MAS, clean the IAC, reset the battery, check the EGR hoses and all vacuum hoses, check fuel pressure, flush and fill all fluids and there you have a basic tune up.

I wouldnt pay anyone to do it, if you can change plugs you can do all this yourself

The 91 is notorious for having issues with the upper and lower intake manifold gaskets when they get older, you may also consider a new set of gaskets and re-sealing the top of the engine.

What is code 41? How did you get it?

http://autorepair.about.com/library/ts/obd-i/bl-dtcs-98.htm?once=true&

 

[flexdog]

Family member basicly gave it to me
It was having a problem with transmission so i had it rebuilt
Thats really all the money I put in it.
1600 for the rebuilt tranny.

I know how to clean the MAS
Do you clean the IAC or is that something just as easlily replaced
Also on the 91 why did they put the oil dipstick in front of the boot for the middle
of the drivers side plug. I can lossen the stick mount to move it out of the way but still have issues putting the boot back on, mainly being I don't fell that it is all the way on but I had some one else check it and we are fairly sure it is back on the plug

The passenger side plugs look like a real pain espcially the rear one, any tricks to getting them out?

Also the O2 sensor is on top of the exhaust pipe and very hard to get a socket or wrench on
whats the trick for it

thanks

 

[flexdog]

Ohh yeah

The gaskets should be OK

the engine was replaced with a brand new one from ford at 100,000 miles

Thats why I am doing all of this work I have a practilly new engine and tranny
and I am only getting 19 to 11 MPG

 

[410Fortune]

19 to 11 MPG is about normal for a 4.0L OHV in a 4500# AWD SUV

Is the check engine light on?

the 02 sensor you can get with a wrench, you need to unplug it first...however if you do not have a check engine light then the 02 sensor is working and does not need to be replaced IMO

the IAC is th eidle air control valve, try a search for how to clean and test it

I am not sure what issue you are having with the oil dipstick, its possible it was moved when the engine or trans was replaced?

 

[flexdog]

yeah check engine comes on after the engine is warmed up thats why i'm thinking O2 sensor

Also think the thermostat may be stuck open because it takes a while to warm up

 

[410Fortune]

if the light comes on then you need to pull the code, it could be MANY things...not just an 02 sensor

The code will tell you what is wrong 99% of the time

 

[techieman33]

If the code is 41 like you said earlier, that is the o2 sensor code. When I replaced mine on my 91 I just used an open end wrench, there isn't much room but you just have to go slow maybe 1/4 turn before moving the wrench. It sucks, but it worked for me. Good luck

 

[flexdog]

I can't get the O2 sensor to budge
I put the wrench on it and that just started to round off the head on the sensor
Decided to cut the damn thing off so i could get a regular 7/8 socket on it
got about half way through and it acted like it didn't want to cut any more
any one else got a suggestion?

 

[Turdle]

http://cgi.ebay.com/O2-OXYGEN-VACUU...ryZ20773QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

You can get this in any chain type parts store also-the ebay ad is to show what they look like-
If you can't get it out-you could weld over the hole and make a new hole. Then weld in a new bung for your new sensor.
The bungs can be purchased at an exhaust shop usually for around 5.00

 

[DeRocha]

I can't get the O2 sensor to budge
I put the wrench on it and that just started to round off the head on the sensor
Decided to cut the damn thing off so i could get a regular 7/8 socket on it
got about half way through and it acted like it didn't want to cut any more
any one else got a suggestion?

I assume you are using plenty of penetrating oil (PB Blaster). Spray it down, let it soak and work the O2 sensor in and out.. If it won't come out anymore then tighten it back down some to allow the penetration oil to work.