ehaiss

I recently purchased a used 2005 Taurus SE with the 3.0l SOHC engine. It is getting poor gas mileage. According to several others that own 05 Taurus's, they are getting 22 MPG city, and 28 MPG hwy. I am getting 16 MPG city and 22 MPG hwy, averaging a little over 20 mpg over a tank of gas.

The car has 85,000 miles on it, and I have done the following:
- Tire pressure at 34 psi
- Trunk empty (except for spare tire)
- Air filter replaced
- Fuel filter replaced
- Oil changed
- All plugs changed with Autolite double platinums (old plugs look wore, with large gaps and rounded electrodes, but otherwise brown to tan, no white, and no black residue).
- Coil replaced
- Wires inspected (at night looking for sparks)
- Both Upstream O2 Sensors replaced
- MAF cleaned (with special MAF cleaner)
- Fuel Injector cleaner ran through (1 tank)
- Dry gas (1 tank)
- Throttle body cleaned (it had significant brown - black buildup that cleaned easily with carb cleaner)
- PCV cleaned
- EGR valve tested (with a vacuum pump)
- inspected for vacuum leak (only the lines to the EGR)
- replaced brakes (no signs of draging)

The car is running beautifully, and seems to have good power. The Check Engine light is not on. My questions:

1. What other lines should I check for a vacuum leak?
2. Do the downstream O2 Sensors have an impact (I have been told no)
3. What else could be causing such a poor gas mileage?
4. Could the Cat's be plugged, even though the car runs good, and no smell of rotten eggs?
5. What about the transmission? Could slipping cause a problem (I'm not sensing any slippage, so it would be very slight if any)
6. What about fuel injectors? Should I pull and clean them?
7. Is the significant brown - black residue on the throttle body normal or a sign of a problem?

ehaiss

Spoke with the dealer, and they indicated my mileage is within the limits of the car. The gov. shows 18 city 25 hwy and allowance for upto 2 MPG varience, so 16, 22 is close.

Does this seem right? What mileage are you getting?

He mentioned the fuel filter, air filter, plugs are 90% of fuel mileage, anything else should set a code.

Sterling_Six

Hello, and good day.

One very Critical item you didn't replace ( that I noticed ) was the Fuel Filter....I have changed my Fuel Filter, and Air Filter on my 2000 Taurus 3.0L DOHC 24v...every 20 to 30 thousand miles..

Try this first..you should see a big difference.

jwko

The user stated they changed the fuel filter.

Sterling_Six

I'm so sorry I missed that...lol....Any ideas what could be the problem?? other than Injectors???

jwko

Other than wires I don't know. If the car is running great with no check engine light I would think all is well. I average around 20-21mpg myself with my 01. To me thats normal.

ehaiss

Yes, the fuel filter was replaced. I did ask another 2005 Taurus driver (that does not have the trip computer), and he confirmed his actual mileage is about 22mpg. I averaged 20.9 before the plugs, coil, filters, etc. I will run it for a full tank and see, but sounds like it might be normal.

The car is running great, much smoother with the new stuff on it.

ehaiss

Update: I got 23.6MPG on my last tank of gas. So that is an improvement over the 20.9 I saw previously. The car is running really well.

360ci

Keep in mind that the EPA ratings were done at 55mph on the highway cycle with no air conditioning running. 2008 ratings changed as they upped the highway cycle to 60mph with the air conditioning running. I drive regularly at 55-62mph and get 27mpg on the highway without fail. When I set the cruise at 70mph, I'm lucky to get 24/25. Around town I average 19

__________________
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!

SHOZ123

If the throttle body had a lot of carbon so does the upper and lower intake manifolds.

You can get NTK O2s on eBay for under $40 each. NTK is the OEM supplier of the O2s. I would not worry about the downstream O2. They do not affect engine performance.