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Catalytic converters.

 
mbattershell
New User
Posts: 8
Joined: 04/13
Posted: 12/23/13 06:07 PM

Aside from all the emissions crap and a whopping fine, what are the negatives to cutting the cats out of a vehicle; to be more specific, a 98 f250. I recently had a mechanic tell me that it was the biggest mistake that I will ever make with my truck. He said it would lose power and mpg...I haven't noticed a difference in either.  

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wayne712222
User
Posts: 62
Joined: 10/13
Posted: 12/23/13 06:29 PM

in most cases.. you will set a code for lack of secondary oxygen sensor signals.. these fine tune the air fuel ratio for optimal emissions..

when the check engine light comes on.. you will have a reduced fuel economy issue..  

when the cats are missing.  there will be reduced back pressure.. hurrah..

only issue is the engine controls require a small amount.. like 1 or 1.5 pounds of back pressure for the egr system to function properly.. what...

there is a rectangular device up on the motor called the exhaust back pressure transducer..  it looks at the exhaust back pressure as the egr opens.. if there is not any back pressure there won't be enough exhaust flow during open loop acceleration mode and the engine will run lean because of the extra percentage of oxygen in the incoming air charge..

its all complicated..

tell you what.. read up on it over at motorcraftservice dot com

read this.. page 4  and page 20 thru 26...
https://www.motorcraftservice.com/vdirs/diagnostics/pdf/obdsm986.pdf

then come back and ask questions.  

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mbattershell
New User
Posts: 8
Joined: 04/13
Posted: 12/23/13 08:13 PM

As for the code being tripped, I scanned it a while ago and it did have a egr code; I don't remember exactly which one...something about "insufficient something or another." It didn't trip one about an after-cat 02 sensor. Is that because when we put pipe where the cat was we didn't disturb either 02 sensor? I would think that it would trip a code because doesn't the after-cat sensor need to read a number lower from that of the before-cat sensor?

I haven't noticed worse fuel economy. It has always been about 15-16 or so. Like I said, I haven't really noticed a difference in anything.

The "rectangular device," is that the dpfe sensor?

Haha dang, yea that is pretty complicated stuff. Pretty informative though also. Can I get more info about my truck from that site too?  

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wayne712222
User
Posts: 62
Joined: 10/13
Posted: 12/23/13 11:20 PM

i have not looked around that site..

its used by ford techs..  very little is free there..

the DPFE sensor is a rectangular OEMs were silver zinc castings.. replacements made by wells are black plastic and have a completely different insides..

instead of having a movable diaphragm that can build up acids and carbons.. then fail.. the replacement black versions have a pair of pressure sensors and are not connected internally..  work far better..   the EGR vacuum solenoids fail also..


by the way.. on taurus and sables with a P0401.. or something in that code range..

the DPFE sensor and the EGR vacuum valve are at fault..

hint anti foulers.. on the secondary.. only mod the first one.. the second one leave alone.. install both.

pick up a $100 scan tool at hf and look at the fuel trims.. if you are running good.. it will be within 3 to 6 percent + or - of 0..

this is the wave form you should see at a hold the throttle pedal steady 2500 RPMs..

O2B2S1 Zps69fd0fbd

my friend jiggled the pedal when i snapped the shots..

when you release slowly back to idle.. you should still have a pattern from 0.09 to 0.8 volts or so...  if your lines go flat.. you might have a leaking vacuum hose to the throttle body..  or elseware..

there is so much out there to learn..  

want to start ...

pick up a digital volt meter.. start the engine and turn on the headlights..

perform the 4 part test below..   if you get more that the 4/100 or 2/100 volts. clean the grounds between those parts..

you can even measure from the wire going into a crimp terminal to the part its bolted to . if you get voltage.. and you might need to reset the meter to 2 volt DC scale..   you have a voltage drop..  fix it.. practice on other cars and trucks.. takes only minutes.. is the basis for every diagnostic test performed..

why.. it makes sure the extension cord is actually plugged into the wall.. before you tear apart the circle saw when it does not work..

Voltagedroptesting  

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mbattershell
New User
Posts: 8
Joined: 04/13
Posted: 12/25/13 12:13 AM

So pretty much the "worst", if you want to call it that, that will happen is a code being tripped that indicates a faulty egr/egr related component that results in poorer fuel economy?  

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