Ok to make long story short i bought this truck used and it test drove fine untill i got it home. The truck like cuts out so i thought it was tranny , but its better with overdrive off "higher rpms". So i took it to tranny shop and they said tranny is perfect change plugs and fuel filter. So i changed plugs and wires to find out it dont have a fuel filter just screen in tank. So i continue to drive it and it got worse it acts as if its getting bad gas and when it does this if you floor it bogs down and wont go on and it pops like thru carburetor but i know it has no carburetor. Then it will act as if it hits good gas and take off. Lets say you keep gas pedal the same and its running bad your going like 50 then when its runs good same pedal it will go 60. So i took it to advanced and they ran the codes heres what came up code 27 /injector #2 , 42/ fuel pump relay 21/ oxygen sensor # 1 shorted hi and 21/oxygen sensor #2 shorted hi and number 7 low engine temp? So tell me please any advice i greatlly appreciate it. My neighbor wants me to by pass cadillac converter but wont this screw my oxygen sensors up? Also is there a way i can clean these sensors? What do you recommend? Heres an update It has 2 oxygen sensor before catalitic converter. So i removed them both just to try cleaning them by setting them in alcohol. So with both removed i drove the truck and it ran perfect? So does this mean the o2 sensors are bad or does this mean catalitic converter is plugged? Because when you remove them it makes it louder but runs perfect. I dont care about loudness or emissions because my state has no test and on my older cars ive just removed catalitic converter because sometimes it cost more than cars worth to fix. Any ideas please?

 

Does your catalytic converter rattle at all when your truck is running? Thats a for sure sign its bad. If its not i would try replacing your 2 front O2 sensors. There is a way you can check them by unplugging them from their electrical connector and reading resistance across them. I'm not sure exactly what your ohm reading should be or what wires to read across tho. I believe its in the haynes manual so maybe its in the merry christmas thread or someone knows off hand.

 

ok thanks alot ill check the hanes manual. the truck does rattle just a little like loose exhaust maybe its coming from the cat.

 

What year is the truck?

 

ok sorry its a 1996 dodge ram supercab 2500 v10 4x4

 

Ah...it's a 96. I'm guessing you have a sensor after the converter then correct? That makes it harder to remove the converter but not impossible. You can purchase an oxygen sensor simulator from this website: www.thefastman.com It's cheaper than replacing the converter, but not exactly legal

If the truck ran better when you removed the upstream oxygen sensors (from near the manifolds) then my money would be on one (or both) of those sensors being bad. Easy way to check would be to reinstall them one at a time and see how the truck responds. You can also check the voltage on them as HansonHVAC suggested.

 

ok i looked all over exhaust and in haynes manual theres only two 02 sensors and there underneath the front doors before you get to the cat. then the exhaust has 2 cats and then it goes into a y into muffler and 1 ehaust pipe

 

Oh, okay. You should be able to pull the converters off without issue then.

It's strange that they Y into the muffler though. Mine go straight into the muffler (dual inlet)...well, mine WENT straight into the muffler. I recycled them after removal...who knows where they are now. [8D]

 

so your guess would it be the cat or the oxygen sensor?

 

I'd lean more towards the oxygen sensor, since your truck drives fine without them in...which it would, until it warmed up and went into closed loop.

If the converter is rattling though, it's not doing so well either.