[maharba]

Actually, that doesn't sound good. What antiseize compound did you use? Are you sure that it is rated for that kind of temperature?

I used PERMATEX's silver anti-seize. "Withstands temperature from -60°F to 1600°F (-51°C to 871°C)" (taken from harborfreight's website). Previously on the car there were trace amounts of copper anti-seize in-lieu of proper exhaust header gaskets which was a source of an exhaust leak. The headlight, license plate light, and O2 sensor wires are not making contact with the exhaust. There is no exhaust shielding and I am considering buying new exhaust shields from Toyota alongside with a new support bracket. There is some electrical tape on some wires near the airbox (from the previous owner) which I thought was melting off because of the lack of heat shield, but it looks fine. The insulation on the engine lid looks fine but I'll take a closer look. It doesn't look like anything is rubbing on the belt, and nothing on that side of the engine was touched except when I degreased the engine.

Googling seems to confirm my thoughts that the burning smell is the antiseize, but I am still skeptical.

I used silver permatex anti-seize when I installed my exhaust 3 weeks ago and still smell that rubber burning odor. Anti-seize is supposed to operate up to 871 degrees C so I imagine its slowly burning off or just heating up and causing that smell. (hdforums.com)

Also if someone installed your O2 sensors with some anti-seize, some extra might have gotten inside the pipe and is burning off. I had this happen to me and after a hard ride it was gone. (1130cc.com)

 

[maharba]

After about 45 miles the 'burning rubber' smell has largely dissapeared, I can still faintly pick it up the smell. It might have been the anti-sieze or the new manifold off-gassing. I did get a CEL for P0440 and P0446 for a failing VSV solenoid which I already have a replacement for and a pending P0420 code which I will need to take a closer look at. Both header O2 sensors are new Denso units so it just may be a undiscovered exhaust leak.

 

[Funkycheeze]

P0420 is low catalyst efficiency which is related to the post cat sensor. Do you still have a main cat?

 

[DrFries]

P0420 is low catalyst efficiency which is related to the post cat sensor. Do you still have a main cat?

Should be an easy fix since he now has some spare spacers

 

[maharba]

P0420 is low catalyst efficiency which is related to the post cat sensor. Do you still have a main cat?

I have not inspected inside the main cat but it is the original one with 190k miles on it... It may have been destroyed or worn out. The left precat (when viewed back-to-front) was intact and the right precat was empty before I replaced the header.