1996 Ford F-150 New Exhast

Tiny
JON WOOD
  • MEMBER
  • 1996 FORD F-150
  • V8
  • 2WD
  • AUTOMATIC
  • 169,000 MILES
Hi guys, I installed new exhast on my 96 f-150 2 in 2out with a flowmaster super 40. Every thing is stock with a fresh tuneup (Motorcraft parts).I did not touch the two front 02 sensors and welded the 02 sensor that was in the cat in the new pipe. My gas mileage now is bad. Talking to some friends they say that the cat 02 gets real hot and thats not happening now. Do I replace the cat 02 with something new or fool the computer somehow? Thanks, jon
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Saturday, October 30th, 2010 AT 8:29 PM

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Tiny
MERLIN2021
  • EXPERT
Check engine light on? When you say you welded the O2, do you mean you actually welded the O2 itself, or the new thread hole? If you welded an O2, you may have destroyed it. Welding heat is higher than the operating range of the sensor, and it probably burned the O2 heating element. I would replace ALL O2 sensors with the mileage on your truck. Also if the original position of the sensor was in the cat, put it back there. It's designed to sense oxygen at that point!
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Sunday, October 31st, 2010 AT 11:13 AM
Tiny
JON WOOD
  • MEMBER
I removed the 02 sensor from the threaded base before welding. All of the 02's have been replaced with new parts. The cats are not in the exhast system now. The the cat 02 is now reading temp in the pipe. Can I change that 02 with a different one with a different heat range? I understand the cat 02 is not getting as hot as it was when it was in the cat. Is there way to take that 02 sensor out of the program with the computer? My gas mileage is bad, and she smells like she running rich. Thanks for your help. Jon Check engine light is not on.
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Sunday, October 31st, 2010 AT 11:40 AM
Tiny
MERLIN2021
  • EXPERT
Your check engine light should be on and P0420 code should be set. There is NO PCM reflash for converter removal that I know of. Your ONLY solution is to put a good cat back on it.
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Tuesday, November 2nd, 2010 AT 10:28 PM
Tiny
CJ MEDEVAC
  • EXPERT
Merlin2021,

Member me?

See my profile

I did a lot of experimenting with O2s, when I installed one in my exhaust, just where the Hedder dumps in.

I did quite a bit of checking when I was doing this (You were my very 1st answerer here at this site) Isn't that special!!!!........My question was about using a O2 sensor to Select the correct JETS, my 4 Barrel Holley Carburetor........almost 2 years ago.

I used both a DIGITAL Voltmeter, set on Millivolts, and also the AIR/ FUEL METER, it uses LED lights RED (lean) Yellow (stoich [close 14.7:1 perfect burn] ) and Green (rich)

Both methods are good for me, voltmeter is more accurate, but hard to keep up with........The lights really show whats going on with the O2 sensor if you are driving alone.

This method sorta sounds stupid for a Carburated CJ 5 JEEP........But after I finally figured out the factor that was throwing me off with JET CHANGING (wrong PCV for the way my engine was configured) , The Darn Jetting got EZ and I was able to Tune my Carb, to make it as efficient as it could be, with the way I drive.

Now, When things were screwy, I put different ones into a COMPUTER CONTROLLED CAR, just to see what both my Voltmeter and the A/F gauge would do. You simply just Jumper wire into the sender connection, lets the computer still use the info, and you can read it too.

Just like they said, The Computer keeps the Vmeter at about 450 MV and the Add On A/F Meter in the middle of the yellow light band (as it constantly adjusts for too rich and too lean) Does this really fast!...........Carb cannot keep up or rather hold this Efficient burn!....But it will help you get the carb right, a lot EZer than "PLUG CUTS", or keeping up with MPG all the time.

Moral of my NOVEL

If you hook up a Air/Fuel Meter or Voltmeter to the EXISTING O2......see what its doing...........Then swap to a new oneNot designed for the CAT! (they come heated and unheated) Try to find an inexpensive one that Connects in the same to your wires, and try it, see if starts showing about 450MV or yellow lights

A small Ma and Pop self service auto salvage yard might yield some really cheap TEST DUMMIES---Insure you write down vehicle info for each (yr, engine, make) so that if you find a winner----you can get a new one for THAT particular application.

I know the other sensors and O2s come into play with all of this, but what should the MV Output be on the CAT O2 if it were straight out of the FORD assembly line?

OK, I shut up now, I am an IDIOT, I am a Plumber with Jeeps.........Scold me now, Merlin2021

The Medic

My Air/Fuel Meter is on my column, beside the tach.


http://www.2carpros.com/forum/automotive_pictures/411289_straight_in_right_lane12_oclock_1.jpg

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Tuesday, November 2nd, 2010 AT 11:45 PM
Tiny
MERLIN2021
  • EXPERT
Your old Jeep dosent have the same type PCM as a 96 Ford, any model. It constantly tries to achieve a 14.7-1 air fuel ratio, controlled by the PCM. An unheated O2 will not perform in these vehicles. Soon ALL states that get federal money for highway projects will require the vehicle to have the same exhaust configuration the car was built with. NO acceptions. Also NO carb on this truck Fuel injected, and his PCM cannot get the A?F right, because the sensor data is wrong. It is trying to enrich the fuel to cause the cat to heat up, his PCM is stuck in warm up mode. (RICH). CJMEDEVAC, I don't mind help if I ask for it, but I don't like Monkey wrenches thrown in my direction. If your advice is followed, will you buy the new PCM for this Ford?
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Wednesday, November 3rd, 2010 AT 12:26 AM

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