My car seems to have lost 4-5mpg all of a sudden with no change in performance. I did gut my smog pump, took it apart and cut out the blades so it spins free, could it be a factor? I am going to replace the Ox sensor as soon as I can get it loose! It used to get 27-30, now its getting 22-25.

 

Do you still have the stock catalytic converter?

 

I am not sure if it is the stock cat. The car had a custom exhaust on it when I bought it. The cat it has may even be gutted. The previous owner did not have emissions and asked for as loud as he could get for a V6. It's welded on and is only like eight inches long so it could be aftermarket.

Could gutting my smog pump make my O2 sensor degrade or malfunction?

 

I dont think so, but I am not sure if gutting the AIR pump to the cat will cause any problems if the cat is still stock setup. It is post O2, so it shouldnt read any more or less oxygen to trim/adjust fuel delivery. Just thought I would ask and spark someone elses knowledge base on it. I take it this was a sudden drop in mileage? Have you run another tank of gas through it to see if it still that low...could have gotten a bad batch of cheap gas possibly?

 

I thought of that myself, but it seems to be the last 3-4 tanks since I noticed and started keeping closer track. I guess its time for a major tune up and see if it helps.

 

Yea, I mean I hate to give that cookie cutter response, but if you havent tuned it up replacing the plugs, wires, cap, rotor, etc. it could be some of the problem. After that, Id say look into the computer aspect...if tune up didnt do anything, somewhere along the line the computer is dumping too much gas. Does it smell rich running? Also, when you pull the plugs, check them and see if they show signs of a rich running condition.

 

fuel filters are cheap, should be part of a tune IMHO