Hi, my 1991 excel was revving out of control back and forth and using gas like a tanker, I used to get about 480 miles to the tank and now get about 153 miles to a tank, then I noticed my motor position sensor had shattered and broken off and was just laying there when I lifted the hood. What does this part do please? and could this be the reason the car is revving up and down, like it's breathing and getting such terrible gas mileage, I've replaced most all of the other sensors and a vaccuum hose and nothing else appears to be wrong. Thank you very much for your response, I'm hoping when I replace this part, all will be well, I've replaced the idle sensor and throttle sensor.

Hello Tobywest.

I think that is part of the timing circuit and that's the bit that tells the plugs when to fire, is that the crankshaft position (CKP) sensor?

You will need to replace that as it will play havoc with your fuel economy and smooth running, my Hyundai is carburetted version so things are a bit simpler, you wonder how these things happen, the worst mine has done is break an exhaust rocker shaft

Thank you so much for your help, this sensor is positioned on the throttle body and I checked a diagram and it said it was the motor position sensor but I'm not sure, I'm going to go to the Hyundai dealer close by here and take the broken sensor to make sure. Then I'm going to ask how many sensors are on this model. That is wonderful that you've only had minimal problems with your Hyundai. My '91 Excel 4 speed went about 91,000 miles when one of my cylinders went bad so I it's been a project for over a year now. I bought a used engine that had about 60,000 miles on it and a second brain, it's had the clutch replaced twice and the fuel pump twice, I bought the car new November of '90, so it's 19 years old but the paint job is not so bad for never being garaged. If I can get the gas mileage back the same and the idle to stop revving I think the battle will be won. Thank you very much for your response and happy driving!! (IMG:style_emoticons/default/thumbsup.gif)

the sensor you are taking about is very easy to replace and would indeed cause all your fuel consumption problems, once you have changed this part you should have no more problems