I have a 94 T-Bird With the V6 TBI, Recently it started not wanting to Idle when cold and the mileage went fron 18mpg down to 10mpg. It has new wires and plugs but that has not helped. Is there a sensor that may be causing the problem?

 

Is the 'check engine light' on? Might be that its running in 'open loop' causing mileage prob.

 

No, the check engine light is not on and the car runs really well, the only problem is that it doesn't like to stay running when the engine is cold.

 

You may want to check the ECT sensor, I've heard that sometime when they are bad they don't set the check engine light.

 

I agree with cctxfish ECT is the engine coolant tempature sensor which you will need a scanner to read it. Its not the temp sensor for the overheat light or the gauge. It tells the computer what the engine temp is as to beable to control the pulse width of the injectors to richin or lean the fuel mixture.

 

Hey thanks you guy's I'll give it a shot. But if the ECT sensor is bad and then I replace it, Should the fuel Milage get better after that?? The car is actually my Mom's. I live in IL. and She lives in FL. I have to go there at the end of this month to do a bunch of auto and home repair as she isnt able to do it herself.

 

Maybe, I'm not sure. If the sensor is always read engine warm (100'-160'). It may make the engine run lean at start-up and rich when the engine is at operating temp?? maybe somebody can clarify

 

If the engine or car has been sitting overnite then when the ECT is checked with a scanner its hould read realitive to the outside temp give or take a few degrees lets say its 70 degrees and the vehicle has set for 16 hours the coolant temp sensor should show somewhere around that and as vehicle is statred it should gradulely increase with engine temp's. I have seen an ECT show 40 below zero when it was 80 degrees out side thus it threw it into an extreme rich mode.

Hope this helps.

Oh and if the sensor was the cause of the problem then fuel milage should come back up.

 

Yeppers , just last week I had a 1984 Merc. Grand Marq. Customer stated running rough , using lot's of fuel. hooked up scanner . Sure enough car was up to operating temp , ECT said it was -40 degrees, That day outside air temp was 92 ( an like I said car was up to operating temp upper Rad hose hot to touch an under pressure ) The check eng lite never came on. an as was stated in another reply, this tells the Computer that the engine is cold hence, it dumps more fuel to the engine ( lets inj stay on longer ),, think of an old Carb. engine with the choke closed about half way!!!! its going to run rough chug black smoke have low power. , The new senser cost roughly $20.00, an you can get them at most auto parts store