1986 Toyota Pickup smells like rotten eggs going up hill and exhaust is popping when shifting

toyota
pickup

#1

I only hear the popping noises (sounds like backfire) when I rev engine, up shift or down shift. Sulphur egg smell only when going up hill.

Can these two things be associated?? I have heard that rotten egg smell can be associated to catalytic converter damage. Could this also explain exhaust popping?

The car also shudders in idle.

Thanks for any help or advice!!


#2

Backfires can be caused by raw fuel reaching the exhaust system, often caused by a misfire. And raw fuel can damage the cat. And misfires can cause rough idling. So yes, all these symptoms might be associated.


#4

A lean idle mixture can cause backfiring during deceleration, so can an exhaust leak.
The rotten egg smell comes from the sulfur that accumulates in the catalytic converter being converted into hydrogen sulfide when the fuel air mixture is rich, which happens at large throttle openings in most cars. When the fuel air mixture is rich, not only is there carbon monoxide in the exhaust, there is also unburned hydrogen gas, and the catalyst reacts this hydrogen gas with the sulfur that accumulates in the catalytic converter and forms H2S, which smells like rotten eggs.
This is common and not a defect, the only way to eliminate this is to buy low or zero sulfur fuel.
The fact that you can smell your own exhaust while driving would be a concern though.