Keep on fixing until it is.

So I find a great deal on a 02 tacoma. The guy that owned wasn't the pillar of maintenance. The oil was thick, the air filter was black, the rest of the fluids had 3 years and 50K on them. I was getting about 20mpg. I get the bright idea to change everything, add a can of BG44K, replace the fuel filter, and all the other little things that should be done on a regular basis and think that maybe I can get 22mpg. Wrong. Now with everything changed and clean I am getting about 17mpg on the last 4 tanks.

 

one possibility is that you are getting more comfortable with the truck and so you are now driving it harder.

i have noticed that my driving habits have a very significant impact on my mpg.

 

Have you done anything different to it? I mean mods like lift and tires, heavy bumpers, etc? Are you sure you did your math right? Did you put in all the correct parts/fluids?

 

Are you sure the original math is correct?
20 MPG is damned good little maintenance...

 

You might also want to pull the plugs and either clean them or change them again. If you ran BG it's possible that all that crud has now moved into the combustion chamber and fouled things up. Or fouled up the cat .

 

Have you been running A/C? I found that my A/C can impact my mileage quite a bit. Sucks - 'cause I live in Phx. Oh, well....

 

Put the old fluids and filter back in...????

 

Oxygen sensor. Between them and the ECU, your car will begin to get lousy mileage as the O2 sensor starts failing. I'll bet it was marginal before you bought it and began a slow death after you did all your BG44 and tuning. Several guys have had theirs fail after doing a Seafoam treatment because of all the junk that comes out in the exhaust.

 

ive got an 01 taco and i get 17... i think thats what they are supposed to get and i know when i first got it i got about 20 and now like 16-17 cuz i drive it normal instead of sissy it around. also is yours a v6 or 4 banger, 4wd or 2?

 

I think most Tacos and Runners get 16-18mpg with city/highway mix especially with the selective few that like to get on the throttle hard even if it is just up to the speed limit.
Even just a 1/4 tank of highway driving will raise your average mpg overall since that 3.4 seems to be happy at around 70mph but going over 80 for long stretches I believe hurts your gas mileage.

 

well im gettign a K&N drop in filter and im doing the deckplate mod so im hopeing to gain 1 ... maybe 2 mpg out of it

 

I am sure about the math. I know it is not an exact science when it comes to filling up that different pumps shut off at different points, but with the continual rise in the price of gas, I always get it as full as possible (I know you are not supposed to fill it all the way up), so that kind of rules out the possibility of not getting the same amount of gas in it.