Running Rich???

[sixonthefloor]

Hey I have a question.
I have an 85 4runner with a new 22RE and a 5 speed with about 2000 miles on it. It has a rough idle like it wants to stall when the outside temp is warm but when the temp is cooler it will be a lot smoother idle. I also smell a lot of fuel at times after start up and in the exhaust when the windows are down. Just incase this info might help it has a stock intake with some kind of after market headers and exhaust. Overall everything works great just curious about this.

 

[zombie]

Has the o2 sensor ever been changed? might be time. Poor fuel mileage and not a dash light was my indicator.

 

[sixonthefloor]

Honestly I have no idea but I should have thought of that. Easy enough though. I bought it from a guy so I'm not sure if he did that when he did all the repairs/maintaince

 

[rafal_c]

what is the 02 sensor? and what does it do?

 

[zombie]

The o2 sensor is mounted in the exhaust manifold or further back in the exhaust depending on the year. It has a wire that plugs into a harness near the power steering filler. Basically it measures the unburnt gasses in your exhaust and from that it determines whether to run richer or leaner. When they get old they tend to not read as well and tell the computer to run richer, using more gas and getting poor mileage. It is often overlooked in older vehicles and not changed at all. The one for my '87 22re only cost about $70. about the price of a tank of gas. I have experienced doubling my gas mileage in other trucks before so it does not take long to pay for itself sometimes. On newer 4Runners they are a lot more money, for an '88 it is in the $200 range and for the 2002, I was quoted around $800 !!!!
My explanation may not be perfect but it should be close enough. :bigok:

 

[rafal_c]

The o2 sensor is mounted in the exhaust manifold or further back in the exhaust depending on the year. It has a wire that plugs into a harness near the power steering filler. Basically it measures the unburnt gasses in your exhaust and from that it determines whether to run richer or leaner. When they get old they tend to not read as well and tell the computer to run richer, using more gas and getting poor mileage. It is often overlooked in older vehicles and not changed at all. The one for my '87 22re only cost about $70. about the price of a tank of gas. I have experienced doubling my gas mileage in other trucks before so it does not take long to pay for itself sometimes. On newer 4Runners they are a lot more money, for an '88 it is in the $200 range and for the 2002, I was quoted around $800 !!!!
My explanation may not be perfect but it should be close enough. :bigok:

cheers mate.. i'm getting around 16 mpg in the city is that about average for everyone???... my exhaust isnt sounding the best plus i think the catalic converter will need replacing soon.. surely it would help my mileage??

btw i have the 3.0L 1992 manual...