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Snowtoy, thank you for the information!! Very much appreciated!! The CAT that is on the rig now is similar to the one in your first photo, on the left - small, and it is welded in. When I purchased the O2 sensor, after the first test failure, I asked about a replacement CAT, and I was told they are all sold as weld in units now (California) due to theft issues. Is there any way to check the welded CAT functionality, to determine if it is "good", and working properly, other than using a diagnostics scope/sniffer machine? Can you please pin-point the VSV valve you mentioned? Possibly post a pic? Thank you!
Here goes:84' 22R, rebuilt ~4 years ago, 20 over, has passed beforeI've failed 6 tests this time around. The only thing i'm failing for right now is NO. As far as the work that a friend and I have done:-rebuilt multiple carbs (finally found a stock one that runs great)-replaced and check every vacuum line as well as sealed every leak-new intake gasket-new spark plugs -new EGR-checked every valve, checked function of all valves + smog pump-new cat (didn't change a thing unfortunately)-replaced header with stock manifold (increased back pressure and cut my NO in half)The only feedback I really get from the testers are "EGR" and "Cat", one finally told me something different and said i'm too lean and cylinder temps are probably too high. I'm about twice as high as i need to be for NO but well below in every other area. Anyone have anything else to check? I've done all i can think to do besides taking it to a gold shield station and bending over. I can post my numbers if it will help. Thanks
I had the exact same problem with my '84 22R. Turns out my 02 sensor was no good! YUP, that's right! The way to tell if it is working and that the electric Diverter Valve is functioning is simple. Take the air cleaner lid off and while the engine is running slowly raise the engine RPM. What you should hear (about 1200-1500 RPM) is the air being diverted to the air cleaner in cycling bursts (kinda sounds like a duck call. you can't mistake it). If you hear that, then it's working. If you don't, then either the 02 Sensor is bad or the Diverter Valve is no good causing air to always be diverted to the exhaust port causing a lean exhaust mixture which will show as High Nox. The electric portion of the Diverter Valve is simply 12V and you can operate it manually to test it. It receives 12V all the time with the key on and is grounded through the Emissions Computer when it see the appropriate signal range from the 02 Sensor. Just FYI When I tested mine, it was diverting air to the air cleaner constantly without the cycling. once I change the 02 Sensor it passed and life was good again.
Thank you for the info fordh8r. So I started it up and tried to see if i could hear the switch at all, didn't hear anything at any rpms. Pulled my O2 sensor, definitely bad. Replaced it with new and it's still not switching over. Pulled the hose off the bottom that runs to the air injection tube on the exhaust manifold so that i could see when it was blowing. It's always diverting air to the exhaust, which makes sense, one of the techs said i had too much air getting put in. So i pulled the valves plug and checked it, hooked up some leads and grounded it out and it closed and sent air up to the air cleaner. Now the question is, why isn't my computer grounding it even with the new O2 at any rpm (truck also warmed up & choke off). Could i just ground it out myself for smog purposes to try to pass? Thanks again
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