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Loss of power on acceleration 03 150 4.6

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Loss of power on acceleration 03 150 4.6

 
  #16  
Old 02-03-2011, 10:08 AM
Dave G.
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They used to sell cat "test pipes". Supposedly for swapping out a cat to see if the problem was fixed. Everyone knew that the cat's were being replaced, rather than tested. Destroying the innards of the cat might fix your problem, but other issues will then crop up, because the PCM will be trying to compensate for faulty emission levels.
 
  #17  
Old 02-03-2011, 07:21 PM
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In newer model vehicles,I dont recommend removing the cats.Not to mention its not legal.No muffler shop will remove them and/or replace them with just a pipe.The fine is quite large.
Removal of the converter(s) will result in very poor fuel economy,and an almost immediate CEL(Check engine light).
These vehicles are computer controlled,and the converter(s) are the main controller of the computer.Removing it will only cause bad economy,and driveability issues.
If you have a plugged converter,take the truck to a muffler shop and have them weld in an aftermarket one.Theyre cheaper than OEM,more readily available,and work just fine.
 
  #18  
Old 02-03-2011, 09:05 PM
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Very interesting and informative thread. Most curious what you come up with...

Good luck,
Dave
 
  #19  
Old 02-04-2011, 04:50 PM
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Originally Posted by n5926g View Post
In newer model vehicles,I dont recommend removing the cats.Not to mention its not legal.No muffler shop will remove them and/or replace them with just a pipe.The fine is quite large.
Removal of the converter(s) will result in very poor fuel economy,and an almost immediate CEL(Check engine light).
These vehicles are computer controlled,and the converter(s) are the main controller of the computer.Removing it will only cause bad economy,and driveability issues.
If you have a plugged converter,take the truck to a muffler shop and have them weld in an aftermarket one.Theyre cheaper than OEM,more readily available,and work just fine.

I agree it is a bad idea to remove cats, but removal should in no way effect drivability.

The pre-cat o2 sensor is what the engine management computers use to set timing, mixture, etc. This is the o2 sensor that counts for drivability and fuel economy. The post-cat o2 sensor (if equipped, and I think everything gas in the US from 2002 has one) really only reads the cat's efficiency so it can "rat the cat out" in the form of a check engine light and code so a defective cat does not pass smog.

Removing a good cat (test pipe) might give a slight increase in performance (including fuel economy since it is all about volumetric efficiency of the engine). Removing a plugged up cat (again with a test pipe) will tell you right away if the cat is the problem, the difference will be night and day.

A few years back we got an early 80s Volvo 240 turbo wagon cheap with a plugged cat. The poor thing barely ran at all. Idled great. But when it came time to go down the road, it barely did. Swapped out the cat, problem solved.

There were some very good tests for bad cats, that do not require replacement, described earlier in this thread that I would advocate over swapping the cat for a test pipe, but the test pipe method is certainly a viable troubleshooting method as well (just a lot of work that may be for nothing).

As long as the front o2 sensor is in the system pulling the cat out of the mix should not impair drivability in any way (unless it is plugged, in which case it will "fix" a problem).
 
  #20  
Old 02-04-2011, 05:34 PM
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Its confirmed plugged cat gonna be getting the plugged one out of there tonight. drivers side if that matters to anybody. Oh and how i love to work on exhaust parts.
 
  #21  
Old 02-05-2011, 01:46 PM
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Runs like new now. Nice to have some power back
 
  #22  
Old 02-05-2011, 02:21 PM
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Glad to hear it...did you replace the cat,or just "eliminate" it?
 
  #23  
Old 02-06-2011, 10:15 AM
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Front cat was shot rear one was perfect. Found a front one for $62 and the neighbor is a good welder. But i can tell you we Knocked the front out out ran a camera (something i didnt know dealer mechanics had ) into the rear one and it was perfect so we put it back up drove it ran great. But decided that $62 is pretty cheap to fix it the right way. I tell you it is nice to have a machanic as a neighbor (even if he is a chev mech) for those i really need help things. Just costs some beer
 
  #24  
Old 02-06-2011, 10:24 AM
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Most excellent...Hope the beer wasnt Imported!..Hell even if it was twas worth it
 
  #25  
Old 07-05-2018, 11:33 AM
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I also lack the power with any 4.6L

I bought a 2000 Ford F-150 4.6L 5 speed 4x4 my true dream truck. Except she lacks the power.

When I first got the truck I replaced all fluids fuel filter spark plugs three coils with very little difference. I couldn’t find a vacuum leak anywhere so I was starting to scratch holes in my head. Later down the road I seized the motor and had it rebuilt with hi performance parts thinking this will smarten things up. WRONG. Even with new cold air intake system mass air flow sensor new O2 sensors in the muffler and no cats to restrict the exhaust I still have lack of power

WTF am I doing wrong.
 
 
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