MPG Has disappeared!

My MPG has dropped tremendously throughout the last year I've had her. It's a 2002 DCSB with a 4cyl. She started at 17.5 MPG when I originally bought it. It's now at 13MPG and not getting better. I'm seeing other DCSB 4cyl owners getting 21MPG. Does anyone have any clue what could be killing my MPG?

 

Have you added a lift, body armor, or bigger tires and wheels?

 

often drops in mpg with no other explanation are because worn front end parts are letting the wheel out of alignment when driving causing drag and tire wear

 

I wouldn't consider it a lift. Put coils in the front and went up 1.25 inches. Stock tire size, no armor. Have a toolbox now. But it's aluminum, it's light as hell.

 

How many miles on the odometer? When was the last time spark plugs were changed? Throttle body been cleaned? General tune up items being neglected can result in a loss of mpg.

 

127k right now.
Spark plugs at 108k. Throttle bottle I believe was cleaned at 108 as well. I'll pull that apart and double check. Couldn't see losing 4.5 MOG from just that though.

 

Bad spark plugs could play a major role in it, but there's one way to find out. I'd check those first to see how they're holding up. Did you use OEM or aftermarket plugs?

 

Maf? I cleaned mine and got 3mpg out of it.

 

I got Denso spark plugs. Can't remember if Tacoma came with those originally.

 

Well, I'll give that a shot tomorrow when there's light.

 

And maybe winter fuel might have a thing to do with it?

 

Tune it up, change the air filter, change the oil with synthetic oil and filter and you might consider changing your diff fluid and transmission fluid with synthetics as well. I've done all that to mine and it gained about 3 more mpg than previously. Also make sure your tire pressure is right, low tires kill mileage in a hurry.

 

I just sprayed mine off with maf cleaner and let it air dry. Put it back in and reset the ecm for goo measure.

 

Yeah Denso came on the passenger's side while NGK were on the driver's. Check spark plugs, throttle body, and MAF first to conclude if they're in working order.

 

Has new air filter, has Amsoil and OEM filters, and I need to look into doing my diff.

 

Sounds like it's time for a major tune up. Clean the MAF as best as you could, check that throttle body again, if it looks dirty it doesn't hurt to clean it. While you are in there pull out the IAC valve and clean the hell out of it, I'll bet it is gunked to shit. Check your spark plugs, if they are Vatolite plugs, Duralast or even Bosch, replace with NGK or Denso of the correct heat range. I'm not sure if you guys run plug wires and coils, but check them as well. Age and deterioration tends to wear them down. Replace your air filter if dirty, change your oil as well. It doesn't hurt to do any of this at higher mileage in that range. Also, lastly, ensure that timing belt is doing ok.

If it's still running with lack of MPG. It's time to dig deeper. I would start with the simple stuff first.

 

Don't mean to sound clueless here, but where is my IAC valve?

 

It should be located not too far deeper into the throttle body area. I haven't seen the way the first gens are setup in a long time so I couldn't tell you for sure it's right there, but on any car around that time period, it's usually in the same area. There should be two small cooling/ heater hoses running into it and a plug.

 

on the 01-04's you don't have one, you also do not have an EGR valve.

the thing that functions as your IAC valve is that small plate on top of the throttle body, removre the 4 or 5 screws and lift the plate and you will find a set of about 6 or 7 holes there, spray a toothpick with carb cleaner and slide the toothpick in and out of the holes until they are clean, then replace the cover and you have cleaned your IAC. short of that, all else you can do is remove the throttle body and clean the dirt buildup inside the bore and around the flap

 

Mine has an EGR valve. I replaced it a mont or two ago along with the cylanoid.