chuckq4yoo

Hey fellas,

So I have a 1994 sc400 and need to get it to pass the smog check soon. Its been about 2 1/2 weeks since it failed but from what it seems it looks like it "barely" failed. (I don't have the test results on me atm). I'd basically want to know what I should do to get it to pass. The car seems to run fine just like most cars around the 190K miles mark. So far i've only changed the oil and the oil filter. Sometimes the check engine light comes on and from what I read from the forums, it could be the o2 sensor or the EGR valve. Would it help to change the fuel filter? I'm not entirely sure what to fix/change to pass.

I brought my car to my dad's mechanic yesterday and he said he cant really diagnose the problem without the check engine light on. Unfortunately, it only turns on for maybe like 1-2 min when I start the car or while i'm driving and then it would go away. The device he used to check to see the codes showed no codes when the check engine light was off. After having the car for about 6 years, it never turned on till last week.

Also I am not sure if its a huge problem but for the past month, every time I start the engine in the morning or even in the early afternoon I get a thick white puff of smoke and then it slowly starts to become clear like water vapor. I thought it was a head gasket failure but I think the smoke should continue to come out while i'm driving but it does not so maybe I dodged a bullet there.

Any input would be much appreciated, thanks guys

chuckq4yoo

lemme add that the HC emissions test was the only part I failed. Max was 57 points and my car measured 66 at 15 MPH. At 25mph, my car barely passed.