can your cat be bad without sending a code? if so how would you test it?

 

Yes, cat won't necessarily set a code. If the truck runs better with the front O2 removed from the exhaust pipe, cat is bad.

 

Thanks!

 

Can you give me the idiot's explanation on why this is so? Does removing the pre-cat O2 sensor simply give the exhaust back pressure from the clogged cat somewhere to escape, making the exhaust less restrictive, or does the exhaust back pressure actually foul up the O2 sensor's readings and cause the fuel trims to get out of whack? Both? Something entirely different that I'm missing altogether?

Thanks!

 

First option. The engine is a giant air pump, if the air has nowhere to go, it can't take any more in, and runs like.... well..... crap. Pulling the front O2 just gives it someplace to go. Bear in mind, it is still rather restrictive, but, it will at least run that way.

 

Anyone else think HeyYou should start a thread or book or something of everything he knows?

 

You, sir, are very kind to offer so much help. Folks like me appreciate it greatly!

 

I'd pre-order that in a heartbeat!

 

Agreed, 100%

 

It would be fact filled, for sure... but I wonder if it would be found in the comedy section, as the secondary commentary is guaranteed to provide a laugh.