Here's the situation....my poor old '98 GF is suddenly getting terrible fuel economy. But not on long distance trips. I drove from Provo Ut to Aspen CO averaging 22 MPG which isn't great but we did have a bunch of cargo on the roof rack ruining aerodynamics. Anyway, I drive long distances and its get fine fuel economy, but my typical commute to and from work is only about 5 miles. From a cold start I have to let the engine run for about 3 minutes befreo I can drive it because I have no power whatsoever when I put it in gear, (it's an auto) the I can't move when I floor the accelerator kind of no power. but it's fine once the engine warms up. My last tank of gas was spent almost entirely on short trips like this, and I only got 13 MPG!!!!

Here's the thought generated by myself and my friends:

The Coolant Temp Sensor is bad and telling my ECU that it's much colder than it really is so at start up it's running pig rich and wasting my fule then. Makes sense to me because I only have this problem when it gets cold and I go from lots of cold starts for only short distances.

In the last six months, the spark plugs, plug wires, air filter, PCV valve, and fuel filter have been changed, so no problems there.

I'm just asking for any other thoughts and input regarding this...and also a question that makes me feel really stupid, where do I find the Temp Sensor on my EJ22? I expected to find it around the thermostat housing but it wasn't there. All help is appreciated, thanks everybody!!!

BRIAN

yes, replace.

You might also want to replace your O2 sensors. I had my upstream sensor die on me and my fuel economy fell through the floor, as the injectors were running full rich all the time. I'm not certain where the temperature sensor is though.

Another possiblility is that the thermostat is stuck open. That would cause the car to warm up very slowly and not run efficiently. Doesn't explain the lack of power though ...

Yeah, thermo's fine...Engine warm up time is normal, so I don't think that it's the thermostat. I'm not the most knowledgable person when it comes to engine management, but my understanding is that if and O2 sensor were bad, I would be getting crappy mileage all the time, not just on the short trips from start up. I've also tried letting the car idle for about 10 minutes after start up to let the engine warm up and my economy was even worse...So does anybody know where that temp sensor is?

If the thermostat is fine, of course then the engine should be at operating temperature.

But with a faulty ect switch, the ecu is being told that the engine is not at operating temperature so it will keep dumping additional fuel to help the engine to "warm up".

The oxygen sensors also tell the engine how its running in terms of emissions and that's why there is an upper and a lower stream oxygen sensor to make sure that not too much or too little fuel is being used.

Also, dumping of fuel can also help to cool the engine down if the ecu is sensing a lean condition.

How many miles are on your car? Are you going to keep this car? If you're near to when the oxygen sensors should be replaced and you're going to keep the car then change-out all three items: engine coolant temperature switch and both oxygen sensors.