Welcome Visitor! Please take a few seconds and 
bufordanthony
Active Member
Got a 99 4.0L manual that keeps popping a 420 code (catalyst effeciencey low bank 1) with a relatively new cat (about 3 years old). Changed the obvious O2 sensors, but no joy. You can tell by the smell and "thickness" of the exhaust that it's running pretty fat, but when I reset the computer and erase the code it smells fine, and check engine light stays off for 30 miles or so. Whacked the cat with a deadblow and didn't hear any rattling, nor does it seem like there is a flow problem. Don't notice any difference in performance other than super shitty mpg's. Also while digging around noticed that my truck doesn't have an EGR nor does it look like it ever had one (nice factory looking cap).
Now having said that, here's what has been upgraded on my truck over the past. Volant cold air, bigger throttle body, JBA headers, Jet MAF sensor, replacing one of the oe double cats with an approved generic cat. Had an MSD on it, but I figured out that they don't like rivers (the hard way), so it's not on anymore.
Now here's my question; What caused the newish cat to go bad? I understand that when I replace the cat (and I'm doing both back to oe this time) the syptoms will go away. However with all the weekend warrior upgrades that I've done to let the motor breath and a lack of an EGR system to "cool" the combustion did I cook it and will I be going through this in a couple more years again? Did I open it too much and now don't have enough back pressure to make the power control module happy? Just curious what yall think? Also what are some good brands of cats for the ol' rangers. The last one I put in was one of those generic cats that look like an overgrown pop can on steroids. I'm beginning to understand that newer emission control systems are finiky, and fickle, and generic just don't cut it. I need one that's going to be more tuned in to the what the rangers need.
Now having said that, here's what has been upgraded on my truck over the past. Volant cold air, bigger throttle body, JBA headers, Jet MAF sensor, replacing one of the oe double cats with an approved generic cat. Had an MSD on it, but I figured out that they don't like rivers (the hard way), so it's not on anymore.
Now here's my question; What caused the newish cat to go bad? I understand that when I replace the cat (and I'm doing both back to oe this time) the syptoms will go away. However with all the weekend warrior upgrades that I've done to let the motor breath and a lack of an EGR system to "cool" the combustion did I cook it and will I be going through this in a couple more years again? Did I open it too much and now don't have enough back pressure to make the power control module happy? Just curious what yall think? Also what are some good brands of cats for the ol' rangers. The last one I put in was one of those generic cats that look like an overgrown pop can on steroids. I'm beginning to understand that newer emission control systems are finiky, and fickle, and generic just don't cut it. I need one that's going to be more tuned in to the what the rangers need.
