hi the problem that im having is for some reason the gas millage is very crappy and i have no idea what is causing it. there are no cel lights coming on and the car seems to be running fine ??? any ideas what could be causing this problem?

 

also noticed the spark plugs are black i checked for vacuum leaks but none noticeable i also did not smell fuel burning around engine. any ideas ??

 

Running rich? Maybe the engine is running cold (stuck-open thermostat) or the ECM thinks so (open ECTS circuit or defective ECTS). Do you get any heat inside with the heater on?

As far as the ECTS goes, it's a thermistor whose resistance varies inverse to the temperature. So, an open in the wiring or the thermistor itself will trick the ECM into sensing a cold temperature. Take the electrical connector off the sensor and then look for a 5V reference voltage on one wire and ground potential on the other with key on, engine off. If they check out, check the resistance across the ETCS and sanity-check:



One other possibility is a fuel leak from the fuel pressure regulator directly into the intake manifold through the vacuum line. Pull the vacuum line off the FPR, turn the key on to prime the fuel pressure, and then look for fuel leaking out the vacuum port.

 

yes i get heat with the heater on just doesnt blow out that much. as for the temp sensor i will check it out later today. ill also check the line on the FPR and get back to you

 

also not sure if this is related but while applying the brake to stop, the car shakes i did replace one of the vacuum hoses because it was bad it seemed to help its not shaking as bad now but it still does.

 

i noticed also when im driving there is hot air coming in under the dash next to my leg and it gets so hot it burns. i dont understand why the heater is off ???

 

I'm sorry but I'm not going to be much help with these other issues since I'm not familiar with the Lumina chassis. Consider getting a factory service manual set (search for "1992 Lumina service manual" on eBay)?

 

its ok man thats another prob anyway lol but as far as fuel consumption ive checked the fuel pressure regulator vacuum line and did not see any fuel. i also checked the coolant temp sensor and tested it cold and read 1.70 ohms when hot it went down to 1.30 ohms not sure if that was good or not so i went and changed it out anyway i checked the new one cold before i put it back on and it read 2.65 ohms. so maby that was bad. i also noticed at the intake manifold there was a ticking sound that was there so maby manifold gasket leaking could that have been giving me bad gas millage ?