hello I have a 91 f350 5.8 that is originally from california.
it stumbles when accelerating or going uphill checked the codes
koeo shows 11 koer 46 thermactor air is not bypassed.
I replaced the thermactor air bypass solenoid thinking that might be it
no change. so my question is what sensor makes it show code 46.
and also since I live were there is no emission testing can I remove all the valves and close off the hose to the heads and just let the air pump
directly to the cat. I will post pics of my system later (can't find camera)

 

Found the camera here are pictures of the thermactor system.
also I have checked all the vac lines and tested control valves they all hold
vacuum.

 

What is the engine vac at idle?

 

I do not know exactly how much vacuum have to get a vac gauge.
another question what would cause low vacuum at idle?
Thanks

 

Leaks. What is the rpm at idle? If u got to buy a gauge get the hand pump one. U can do more with it. How did u test the hoses ?

 

I used a converted pump to check the lines. after 5 minutes when removing pump there's a good pop so I am pretty sure the lines are good.
I also read about testing the check valves I have three valves two that go to the cat and one to the heads the ones to the cat work. the one to the head works but it is real hard to blow air through. is that normal or do
I have a partially clogged check valve or head crossbar. Thanks

 

Code 46 also states "Electronic Ignition – primary circuit failure coil 2 – Ignition Systems"

I am chasing code 45 and my truck has a terrible hesitation after the trucks get to operating temp. After truck cools down it runs fine until operating temp.

 

The other meaning for code 46 says cars only for the DIS coil pack circuit failure in my manual

 

after alot of fiddle farting around I think the problem is solved.
replaced the oxygen sensor and ran the codes 11s all the way
no more code 46.