Is this normal????

I have a 2008 V6 PreRunner. I have always gotten 20MPG since I bought it new. I changed my spark plugs (Denso from dealer - checked gap and they were 0.040), cleaned my throttle body, MAF, and cleaned my Borla air filter. Now I am only getting 16MPG. My Tacoma runs great, but the MPG are not as good. The ECU was reset after all the work was completed by unplugging the negative battery terminal for ~2 hours while I did everything. I have been through one tank of gas. Should my truck have already "learned" the new plugs and cleaner throttle body?

Did I do something wrong???

 

What kind of spark plugs did you use?

 

Denso from the dealership.

 

Well, you busted me! I did drive it a little harder at first, but now I am back to my normal driving. I only did it for about the first quarter of a tank.

 

0.040

 

^That was probably the problem. Driving a little harder along with the ECU resetting. Check the 2nd tank and see if you have an improvement

 

I wouldn't think that little bit of harder driving caused my MPG to drop off by 4MPG. If that is so, I would hate to think if I was towing a trailer all of the time.

 

Towing a trailer full time will net you around 16 MPG or less depending on the size of the trailer. Personally, I've noticed large swings in MPG if I'm driving more aggressively for a tank.

 

Thanks for all of the responses.

 

UPDATE: I have used another tank of gas and filled up again. The second tank after the plug change was much better on fuel mileage. I am now back to my 20MPG.

Thanks for all of the input.

 

That's Awesome! I get 13 mpg. LOL!!!

 

I'd wager some of that was your ECU reset.

Last time I did it, my truck had NO idea what it was doing. It was like the little gnomes that live in the engine computer were drunk and couldn't figure out what to do. Timing was way short, throttle input was MASSIVELY dampened, and the cruising mileage sucked. It took 300 miles to come back to something reasonable.

Toyota kinda went the old EEC-IV Ford way this time - let the computer program itself to the engine and then they won't have to be so close on factory maps.

Now I absolutely DREAD unplugging my battery.

 

Imagine if you had the tires in your signature on your Taco!

 

Yes. That is what Chriss4x4 told me. And he was right.

 

i havent done anything to my truck, and my gas mileage has stopped. it has to do with the ethanol in the gas i believe.

 

What are you getting? I have always gotten 20MPG since I bought my Taco, until I did the plugs. I then dropped to 16MPG for 1 tank of gas. Now that I have completed my 2nd tank of gas since plug change (~300miles), I am back to 20MPG.