89 throttle/fuel mix

[rcrawley]

If the car is driven without turning off engine there are no problems no matter how long the car is driven. If the car is started, allowed to run for more than a minute and turned off upon restarting the following problems occure.

When the RMPs are maintained at a moderate level without moving the RPMs will decrease to a low idle without moving the paddle. If I attempt to drive the car appears to have a very rich fuel mix and contunally looses power.

Help, the car is in amazing shape otherwise.

[AzTumbleweed]

Does that have a carburetor? Almost sounds like the choke plate is closing.

[rcrawley]

Yes it has a caborator. I am suspecting the problem is electronic but cannot come up with a bad component. Have replaced EGR and TPS. When the TPS is unplugged the idle problem went away but the car is not driveable.

[denisond3]

I thought 89 Escorts had throttle body injection? I could also suspect the manifold pressure sensor or the fuel regulator. If its running rich, the spark plugs will all look dark, not a light brown or white as they should. I also think the TBi units had an air bypass valve (by whatever name Ford has for it). If they close too far the idle will be too low. They eventually get coated with crud and carbon, and are hard to clean. Squirting throttle body cleaner into them while the engine is cold and running at a high idle might clean it though.