sick Metro, no codes.

96 Geo Metro runs poorly and has black smoke. Tried two different places to get it diagnosed, and the computers will not communicate with the car. Car does run, but uses a lot of gas. The service soon light is on, have installed new timing belt, double checked timing marks. New cap, rotor, plugs and wires. :banghead: Replaced coolant temp sensor. Cleaned all the grounds I can find, checked ground wires to the computer itself, and those showed to be fine. Computer was removed and sent in for testing but did not find any problems. Is a 1.3 4 cyl. looks like it should have Idle Speed control, but is missing. Was told that 96 did not need this Idle Speed Control. Built 10/95. How can I get it to comunicate with my scanner? Or anyone elses computer? Any other Ideas? Stepping down on the throttle makes it fall on it's face. Is getting vacuum signal to EGR valve even while cold and idling. Plugged the vacuum line for a minute and idled much better. :banghead:

Thanks, Roy

egr may need cleaned or replaced. the computer only diagnoses electrical problems and takes sensor readings. it sounds like your egr transducer is fine (the electric part) but that the valve itself may be mafunctioning. both the valve and the transducer should be cleaned or replaced together at about 75 to 100k miles.

A scanner will only pick up dead sensors. if a sensor is out of calibration, but still creating voltage, it will think it is operating normally. Check for vacuum leaks, and I bet your oxygen sensors are toast.

Thanks for your suggestions. Both oxygen sensors look new, and this rebuilt engine was put in about 20,000 miles ago. Had been running fine. This car was brought to me because no one else in our area wanted to work on it. It has been in three shops here before me. I am beginning to believe this car has a bad ECM. Especially since it will not comunicate with anyone's scanners or computers. Had a Mitsubishi Eclipse do the same thing, found out the hard way someone had changed the computer out, and had installed the wrong computer. Also talked with dealer about 60 miles away and he thinks it is computer also. Will try to use vin # to determine if this is the correct computer for the car.