Thanks for the tips jbrew!

My manifolds look just like jmg's! Rusty as all heck! I've shot some PB blaster on them a couple of times already and the nuts and studs look better already!

My plan is one side per weekend, since it's a daily driver, I need to drive it on Monday!

Mitch

 

What makes that job a nightmare is the exhaust flange bolts breaking. My Drill Doctor and I spent all night drilling them out one time - The manifold itself fell off after the bolts where out. The next time I did it , I had the manifolds (Long Tube Headers)

 

Mitch

I haven't done exhaust manifolds and I don't know if this will work, or is even safe to do (fuel lines nearby?), so take with caution. But, back when I did auto body work for a living, I would occasionally run into frame bolts, suspension bolts, etc. that looked as bad or worse than the exhaust manifold bolts on my truck. They would be as stuck as stuck can be and I knew they would break if I made any attempt to get them out of there.

The trick I would use is to take an oxyacetylene torch, stick it on the bolt, and wait until it got RED hot. Once I did that, they would back out with a ratchet very easy, no impact tools needed. Not everyone has access to a torch, so this might not be helpful, and again, be careful as to where you point the thing. But never once did I have a bolt break on me, and never once did I need an impact tool of any kind to remove them.

 

Cool guys, thanks for the additional great tips! I'll get some new flange bolts and borrow my Dad's oxy/acc torch! Didn't mean to hijack the thread, but I'm glad it's a sticky!!

Mitch

 

Oh yea , that will work

Good luck Mitch - BTW - Never use Bosch plugs in these motors

 

Great write-up
I was planning on doing my OEM 02's on my truck this weekend and now i know what has to be removed before i start!!
Thanks

 

Yea , the old ones

 

Edit.... I changed them this morning Jim and the pinging i had is completely gone They came right out and if you have a body lift you don't have to remove the inner fender Also nothing on my truck is rusted so i just used a 22mm wrench for the 02's instead of buying the tool.

 

TROUBLESHOOTING

Before suspecting the HO2S, the wire connection to the sensor should be checked first. Examine the wires for chafing. Then inspect the connector on the sensor for moisture or damage to the pins. Because the signal voltage is very low (less than 1 volt) the connection is sensitive to damp or poor connection. The heating voltage and current should also be checked and these connections should be clean and bright.

If a careful inspection of the wiring raises no concern log on to the PCM and take a reading of the sensors after warming the engine for at least 3 minutes (to allow closed loop to commence.) Several points should be borne in mind:

1. A sensor should read high (0.6 to 0.9 volts) or low (0.1 to 0.4 volts.) It should never read 0.0 volts.

2. On V engines, do not compare the front sensors together - they will not show the same switching, nor should they - the two Banks of the engine are two separate fuelling cycles.

3. Any sensor showing a negative value (-0.1 to -1 volts) is showing a CSD and the ceramic body has broken. The sensor must be replaced.

4. A Front sensor HO2S11, 21, should be showing a regular 'switch' from high to low, at a frequency of about .7 seconds. Periods of 'flatlining' ie no switching, means that the sensor may be deteriorating and may need to be changed if DTCs are being generated.

5. A front sensor that is not switching may not be faulty, even if DTCs are generated. Check the Long Term Fuel Trims (LTFT) - they may be consistently positive caused by an air leak, or either negative or positive by a faulty fuel pressure regulator, or negative caused by a faulty MAF sensor.

6. A rear sensor HO2S 21, 22, operating correctly on a good catalyst should show a very slow switching.

Heater Circuit Malfunction

Receiving HO2S Heater DT codes P0141/P0161 and P0135/P0155 some additional work can be done to pinpoint the cause. In the event that DTCs demonstrate a concern with more than one heater at the same time then the owner must suspect a wiring rather than a sensor fault. There are only three main splices in the wiring between the PCM and the HO2S heaters and the following diagram will be useful:



Splice A provides the power for both upstream and downstream sensors. A wiring problem with this splice will produce the DTCs P0135/ P0155, P0141/P0161 together, (only 2 of those for four cylinder engines of course.)

Splice B provides the power to the Upstream (front) sensor(s) and generates the DTC P0135/P0155

Splice C provides the power to the downstream sensor(s) and will produce the DTC P0141/P0161

 

I just read this thread because I have to change mine when weather allows. But you have an entirely different setup. First, I only have ONE O2 sensor. And mine is in a small (about one inch) piese of pipe that goes between the crossover pipes. I am posting this because maybe someone can advise me how to cope with mine. The replacement crossover pipe for my truck (1990 F150 with 5 liter eng.), costs almost $300 and included the cat. converter.
Yet, on my truck, the cat conv. is a separate piece and looks fine. Being a farm truck I'm not going to spend that kind of money on it. I intend to rig up some sort of homemade crossover, or see if I can find a pre-made standard crossover that will fit. But two things come to mind. First, so I really need a short piece of smallish pipe between them two exhaust pieces for the O2 sensor, or can I just place it somewhere near where the two pieces join? Second, what can I use for a threaded piece to screw it into (what are the threads and hole diameter?

Then comes my next question. As I said, this is a farm truck. I dont intend to spend a fortune on it. I have a mechanic I often use when I get into situations where I am not able to do the repair, or just refuse to lay on the ground in cold weather. He told me that I may lose a little gas milage without the O2, but said "for the cost of replacing the thing (with the exhaust pipes), you might just leave it, and went on to say "on a truck that old, it really wont matter that much if you dont have the O2, and it will take a long time to pay it off with the small savings in gas usage". So, do I really need it? And, what if I placed a jumper across the wires *there are three*?

I know it's best to do everything as it was built, but there are cost limits for waht I am going to stick into a $500 truck, and I already spent another $500 to replace the brakes and the front 4WD axels and U-joints.

I have always driven carbureted vehicles, so just how critical is all this stuff on fuel injected. Where I live, there are no emissions tests, so it's just a matter of getting her to work as well as possible without spending a lot.

Thanks

George

 

Please post in the correct forum . If you would copy and past your post in pre-97 forum, here -

https://www.f150online.com/forums/pre-1997-models-51/

and start a new thread, you may have better luck.

This is more of an imformative (sticky) - A place to get info.

After you have successfully moved your question (post) to the proper forum, please delete the one above.

Thanx.

 

I have a 04 F-150 with 4.6L and recently replaced all four O2 sensors and am still getting an error code. Are the sensors interchangable or are there specific sensors before and after the converter?

 

Post as a new thread and you'll likely get some responses. This thread wasn't intended as an 'ask all your O2 sensor questions here' thread. Good luck.

 

how much does replacing your o2 sensors effect your gas milage and hp?

 

wont do anything unless there is something wrong with the ones you have now