Lazy/Delayed Start & poor gas mileage '97 Aerostar

[teakstone]

My '97 AWD 4L Aerostar has great performance, great acceleration, top speed of over 100mph. I don't normally drive like that, I was trying to clean the fuel injectors by gunning the throttle.

The problem, poor gas mileage, about 250 miles to a tank full. No codes showing. Brakes not sticking, tires inflated to 32 psi. Changed plugs. Next on the list is the fuel filter.

The symptoms other than poor fuel economy, is that the engine at times takes too long to fire, perhaps 2 to 3 seconds of cranking. Any suggestions on how to proceed to get the fuel economy up and the the lazy/delayed start down?

[rhandwor]

A bad thermostat not getting up to temperature causes the computer to use to much fuel as it stays in closed loop. Feel another cars upper radiator which doesn't have problems and then feel your hose it is easy to feel temperature difference.
An out of calibration temperature sensor can also cause problems. They used to be around 4 ohm at 80 degrees and around 40 ohms when hot. They don't publish tables any more so they can sell scan tools.

[teakstone]

Thanx rhandwor,

I bought a new engine coolant sensor. Compared the resitance values and the old one is off by quite a bit. I hgope that solves the prob. BTW at about 60 defrees the resistance is about 45kOhms and at about 170 it is around 10kOhms. The old one was 38k and 14 k repsectively.

I did some further research on coolant temp sensors, and Bosch states that the sensors degrade as they age.