92 Z34 fuel running rich.

[millerwl71]

I got my cat inspected by two differnet places and they both said that it is alright. The problem I'm having is, it real stinks like rotten eggs when going at freeway speeds and then coming to a stop. Normal driving, I do not have a bad smell. Both places said my fuel is running rich, or they said it's dummping to much gas and that is why the cat smells after freeway speeds. Anyways, anyone know where I should start to find why its running rich? Thanks.

[5speedz34]

Post in Powertrain please.

[GOT2B GM]

A properly working cat. convertor should have a rotten eggs smell when hot.

[redimpulse]

Actually under normal circumstances, a properly working cat will have no smell. The "rotten egg" smell has a couple causes:

1: Bad cat. But since you've had it tested multiple times, we can pretty much rule that one out.

2: Nasty gas. Some gas stations for one reason or another can cause this. I think it has something to do with sulphides, hence the rotten egg/sulphuric smell. I've noticed Citgo gas gives my car this issue quite often.

[jeremy]

moved to powertrain

[millerwl71]

I put the best gas in once a month and never go citgo. But what about the fuel running rich or getting to much fuel. That is what I was told. That it's dumping to much fuel and that is why my cat stinks so much after freeway speeds.

[redimpulse]

(forgive my obvious lack of knowledge on some of the older engines)

Have you checked your MAF? It could be dirty, causing a misread; but not bad enough to throw any codes...