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I have a 2001 ranger 2 Ed and I was wondering what’s the easiest way to by pass my cats I think they are backed up I have a big loss of power

 

Use a Vacuum gauge on the engine, $20 tool that can tell you A LOT about ANY gasoline engine

Hook up the gauge to intake manifold port
Remove cover from throttle linkage in engine bay to you can manually open and close the throttle while watching the gauge

idling engine should show steady 18 to 21 inches of vacuum, depends on YOUR elevation above sea level, normal can be as low as 16" in Denver, 5,000ft elevation

Open throttle all the way and vacuum should drop to 0 or close to it quickly, slow drop can be exhaust blockage
then let throttle snap closed
Should see an instant return to 18-21" or a little higher then back to 18-21"

If its slow to return to 18-21" then could be exhaust blockage

Open throttle about a 1/4 and hold it there, vacuum should go down a bit then come back up once RPMs are steady, if you see a slow drop in vacuum at steady higher RPMs, then exhaust is blocked

Good read here on vacuum readings and tests: https://www.gregsengine.com/using-a-vacuum-gauge.html


A gas engine is an self power air pump, sucks in an air/fuel mix, burns it, then expels it to get new air/fuel mix to burn
If it can't expel it fast enough it can't pull in as much new air/fuel mix, so loss of power

best way to test a "pump" is with a pressure gauge, in this case negative pressure guage

 

https://www.onallcylinders.com/wp-co...-reading-1.png

ron - i like this chart better. easier to compare what your gauge is doing