1998 Saturn failed smog check
My 98 Saturn SC2 automatic with 20500k miles. I had to take it to a smog star and they said that it does not pass the HC, says it is emitting 54 when it should be lower. Instead of changing the cats, how can I fix this? The guy said I should check the spark plugs, anything else?
Well a 1998 model is equipped with OBD2, have you checked codes and live data?
At idle, short-term, cold jumps around -17 to -18. As it warms up it jumps in between -23 to -25. It drops to zero when raising the RPMs. Long trim stays in -2.3
Of course the engine is running open loop when cold but it should settle down and go closed loop once the O2 sensor warms up. It appears that the computer is subtracting a lot of fuel at idle. What do your spark plugs look like, are they carbon fouled?