Taurus '00-'03 fuel consumption?

[serge_saati]

I have a Taurus 2002 OHV Vulcan engine, and I can say that it uses a LOT of fuel for a sedan. It has 89,000 miles and it's in good condition. The only issue is a minor misalignment.

It makes 15.7 mpg mix driving (70% highway, 30 % street) A/C off
It makes 12.5-14 mpg city driving (25% highway, 75% street) A/C off

I calculate by filling the tank, wait that it reaches ~1/8, fill again and see the distance, the correct way. With a 13.2 US gallon fill I makes 166 miles in city.

Engine has a lot of power. And 610-650 rpm stable idling. No vacuum leak nor big hesitation.

Tune up had been made before buying the car (4 months ago):
-air and gas filter changed

I replaced the 6 plugs few days ago because the gap wasn't good (not related to fuel consumption, just one misfire in highway one time). But no change in mpg.

And yes, my driving is perfect. Drive slowly, brake slowly, drafting, constant speed, no load, not too much traffic, defroster off...

So the question, is not what to do to improve my fuel consumption, but what is YOUR fuel consumption for 2000-2003 Taurus OHV? I assume DOHC is much better.

[shorod]

A couple of things to try would be to clean the MAF sensor, then check the Engine Coolant Temperature (ECT) sensor readings to see if they are reasonable both at cold start and after the engine is up to operating temperature.

If you have scan tool with datastream mode, that can make monitoring these parameters, along with the O2 sensors and fuel trims much easier.

-Rod

[serge_saati]

You are right, it was the MAF sensor. I disconnect it to run in LIMP mode, the car acceleration is MUCH smoother w/o any hesitation. It drives like new. Better engine noise too. I made 1/2 miles like that. Tomorrow I'll clean it.

Thanks for your help.

[serge_saati]

Ok, yesterday I checked the MAF sensor condition, it looked ok. I still clean it with brake cleaner.

But the car still surges/hesitates from a stop sometime when I press on gas, I believe the problem is not solved. It does that like 20% of the time.
It does it more when engine is hot than when it's cold.

**When I said hesitation, I don't mean a delay between pressing gas and moving. It moves instantly. I mean it accelerates too slowly, so I press gas a little bit more, it doesn't react, then it surges and operates normally. Acceleration is not smooth at all.

But when I'm in LIMP mode, it runs perfectly.

About the ECT, at 45°F I've 55.4 Kohm.
At operating temp, I've 2.44 Kohm, so it's good.

I don't have a scan tool with datastream mode, I'll take it to someone who can monitor my PCM data and tell me if something is wrong with it.

Still waiting for fuel consumption of other Taurus 00-03 owner.

[shorod]

The MAF sensor monitors the amount of air flowing in to the engine. When the MAF sensor is unplugged, the ECM needs to rely on other sensors to determine approximately how much air is entering the engine. If you have a vacuum leak and the MAF sensor is working, the car will misfire because the ECM uses the MAF sensor to calculate how much fuel to add. But, due to the vacuum leak, there is additional air in the engine so the air - fuel ratio is off.

So, if you have access to a vacuum gauge I'd suggest you check the manifold vacuum when the engine is running poorly. Since it seems to act up more when the engine is warm, it's possible the leak is something related to temperature like a manifold gasket or EGR system.

You could also check fuel pressure since the fuel pump will heat up when running for several minutes, especially if the tank is near 1/4 full or less.

-Rod

[serge_saati]

I wouldn't be surprise to have a vacuum leak in my lower intake manifold. Since it leaks a little bit of oil and antifreeze from there. I'll check.

[serge_saati]

Ok I replaced the lower and upper intake gasket manifold 2 weeks ago, now my fuel consumption is 13.5 mpg in city. It's not a big difference. But the good point, I almost no leak antifreeze. Maybe 3 onces in 2 weeks, it's better than 1/2 gallon in a day.

[serge_saati]

Ok now my fuel consumption has decreased a lot. I made 90% highway, it's now 18.4 mpg.
It's the first time it's so much. So the vacuum leak was the culpirit.