Poor Gas Mileage and Funny Smell on Exhaust

[bsupra]

I have been getting very poor gas mileage on my 91 turbo. Before, I had that massive exhaust leak due to the strip exhaust manifold bolt. Thanks to Jose, they put my car back to life. It did not take long before it had this funny smell and poor gas mileage. The smell is like bad fumes from exhaust, not sure if its fuel. Car runs fine though. gas mileage is around 15 mpg on city and 18 on highway. I had an 89 turbo before but i get 18 on city and 25 highway.

Is it becuase I have been driving the car with bad exhaust leak before it got fixed? No check engine light either. Thanks

 

[jetjock]

Well, an exhaust leak upstream of the O2 sensor can cause poor fuel economy. Now that it's "fixed" you probably have other problems with the engine not being in fuel control. Check OX on the diag block and see. Either that or this hombre Jose did a crappy job. Maybe you should bring the car back to him...

 

[Green7mgte]

is it a sulfur smell? might have a blocked cat..
don't know if that would cause your mpg to suffer tho.. it might. ?

 

[bsupra]

is it a sulfur smell? might have a blocked cat..
don't know if that would cause your mpg to suffer tho.. it might. ?

I think your right. Thats why I could not explain the smell. I know it was not fuel. So, that means I have to replace cat now huh? Thanks for the technical advice.

Any chance that you might have an idea what caused the cat to get blocked like that. Probably 02 sensor or something else?

 

[Another MkIII]

Usually, a plugged cat is caused by one of three things:
1) A lot of short trips that cause the cat to become coated with sulfur because it never gets up to temp.
2) Extra unburned fuel melting the cat either from running extremely rich causing the cat to melt, or (more likely) a misfire that causes unburned fuel be dumped into the exhaust.
3) Crappy gas (usually not a problem but still possible), or an incorrect fuel or additive that coats the cat.

1 and 3 can usually (not always) be fixed by driving it hard and getting the cat hot enough to burn off the contaminants. The second one requires replacement of the cat. Hope that helps.
-AM3