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Catalytic Converters

Discussion in 'Performance & Fuel' started by 95C1500, Aug 17, 2013.

  1. 95C1500

    95C1500 Member 2 Years 100 Posts

    I just had my Cat replaced with a Magnaflow (not a high flow cat). I'm currently getting 12.5 mpg. Would a new cat (old needed replacing, honeycomb was in the muffler) up my mpg's?
  2. dobey

    dobey Rockstar 3 Years 100 Posts

    Did your MPG go up?
  3. 95C1500

    95C1500 Member 2 Years 100 Posts

    just filled up yesterday. Just asking to see.
  4. marksoldtowne

    marksoldtowne Member 1 Year

    The catalytic converter in a vehicle’s engine plays a crucial role in maintaining its efficiency. Essentially, the converter’s function is to burn off excess hydrocarbons in the exhaust system, which makes the engine run clean.If your car’s catalytic converter might have a problem, checked it as soon as possible.
  5. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    You might see an increase, it really depends on how bad your old cat was.
  6. 95C1500

    95C1500 Member 2 Years 100 Posts

    Chunks of the honeycomb fell out of the muffler.... pretty bad imo lol!
  7. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Your truck doesnt have an after cat sensor if I remember correctly, so the only possibility is if it increases the backpressure slightly and improves low rpm torque. If it does improve you wont see much.
    Thats real low mileage, from the picture it doesnt look like you have real big tires, and Im guessing you dont haul trailets or huge loads all the time.
    Do you have a heavy right foot?
  8. Jamm3r

    Jamm3r Member 1 Year 100 Posts

    No, however, there's a pretty good chance that you have a leaking fuel pressure regulator which contributed to the early failure of the cat.

    You have the 5.7, right? Fixing a leaking fuel pressure regulator will improve the MPG, by a lot. They leak into the intake manifold where you can't see it, then the truck runs rich and burns up the cat.
  9. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Thats along the lines of what I was thinking Jamm3r, something more than the cat causing low mpg, and as you noted causing an earl and for a cat what could be considered a catastrophic failure. A rich condition would do this.
    It would be interesting to know if prior to the cat burning out it had gotten hot enough to glow.
    I had an early 90's k3500 dually that looked like it had neon lights under it from a rich condition, after a few mile it would glow enough to reflect off the pavement. I didnt catch on until after the third person commented I had left my neon lights under the truck on, it was also giving me clues like poor mpg and heavy fuel smell in the engine oil.
  10. ChevyBoy2009

    ChevyBoy2009 Rockstar 4 Years 500 Posts

    My brother-in-laws 1996 Chevy 1500 2wd with the 5.7L Vortec gets around 18 mpg or so...he also has a heavy foot

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