Smog Test

CRAIGTAURUSOWNER

MEMBER
FORD TAURUS

My 98 Taurus wagon (3.0, 24 valve) with about 130,000 miles has failed CA's emissions test with high CO, HC, and NOx. The plugs were replaced just after 100K. It runs a little rough but strong, and mileage is low at about 15mpg. I replaced the two front O2 sensors, then got the maintenance light. A repair shop said there was no pwer at the ECM and replaced it for me. The light cleared, but ran the same. Cleaned the throttle body, replaced suspect vacuum hoses, replaced IAC valve, checked EGR which moves freely with vacuum pump, replaced plug wires and fuel and air filters. Any suggestions?

1 Reply

NOS

MECHANIC
320 POSTS

They only alow 600 parts per million on HC which is hydrocarbons. Car is running to rich that is what there tring to tell ya. You have a vaccum pump check the MAP sensor it has to get good vaccum and it has to hold good vaccum anthing less and it won't work right. Also if possible replace you temp sensor this one along with map sensor control the fuel what is happening is that it is running to rich and that is not good for one of thoes test. You get the HC down and the rest will fall into place and you'll pass you need to get your engine leaned out. If the map reads a cold engine it will tell the computer the richen the fuel. A messed up thermostat will goof things up also it will give the temp sensor the wrong info and it sends wrong info to map and map sends wrong info to computer in theroy if you could stuff more air into your engine than fuel it would pass in a heart beat(NOS)