91 3.1L chevy

Here's one for ya! 91 Berretta 3.1L somedays at highway speeds the thing will lose power and the engine light will come on then go out. When you mash the throttle during this loss of power phase the thing blows black smoke out exhaust. Some days it never does it some days it does it several times. My commutes are 40 miles one way at 80 mph--it never does this at around town commutes--always starts and idles great and has plenty of power(as much as a 3.1 will put out--stock) 110,000 miles owned since 30,000 miles and always do regular maint. Fuel mileage went from 28 to 18 mpg! Pulled the codes and got #44 O2 sensor lean condition? O2 was replaced last year--when it would not idle and got code #13. The lean condition does not make sense considering the mpg and black smoke. Thinking about replacing O2 sensor!? Any similar stories or ideas?

 

O2 sensor should be changed every year. Most are one wire sensors and get poisoned by all the junk in the fuel and cannot "burn" off the excess deposits on it.

How does it run on a gas analyzer? What kind of emission numbers do you see?

The computer is probably trying to cut back the fuel trim/mapping based on the rich condition.

 

Gas anaylizer? Emissons #'s? This is Michigan baby--anything goes out here! I will probably do the O2 it is cheap and easy. But every year? That is not part of the regular main. schedule! atleast not in my owners manuals--I got a '98 GMC Z71 with less than 40K--you think it needs an O2 sensor??

 

If your fuel is like what we have out here, yes!

The sensor on my 84 Olds 88 gets done every year. As you said, it's cheap and your gas mileage improves.

 

Done deal-- running good for now--$21.99 for the sensor $7.99 for the socket to remove it--funny thing is--I know I bought one of those sockets before!!

 

Lol. Way to go! Good deal.

I always keep my tools organized so I can find it. I've got four rollaway toolboxes now .