I have a 305 TPI, 119k, engine is in good shape, no leaks, not burning oil. I took it through emissions for the frist time in 10yrs (funny story about how I got out of the last 5 tests, I will tell you if you ask) so anyway I failed. I failed on my Hydrocarbons (HC) by .72 GPM; and my Oxides of Nitrogen (NOx) by .3 GPM. Note: I have a manual fan switch for my radiator and before the test I forgot to trun it on, so the engine temp got up to about 300 degree's during the test) I have a few ideas but I need to know if its right. First Retard the timing aliittle (for VEIP test only), Keep it cool (i.e. trun on fan..lol), change the oil, and top off coolant. Do you think this is enough to pass?

 

Retarding the timing and changing oil is not going to make your car pass. You should set the timing to the proper spec for emission tests. Letting your engine get very hot is not good for NOX emissions. You should buy a kit to allow the fan to turn on at a specific temperature. They are not expensive and prevent possible damage from forgetting to turn it on. Assuming you have all the proper emission equipment on your car I would look at the regular tune up items first to make sure they are in good condition. The next thing I would look at is the O2 sensor and a clogged EGR.

 

All i did to turn a very failing car into a very passing car is retard the timing about -2 to -4 degrees. I had it advanced 6 degrees when it failed. I passed every test with only half of what failing was at least.

I just let the car heat up real good, turned my fan on for the tester guys so it didn't overheat. No other changes. (oh, I have a real nifty toggle switch by the steering wheel for the fan ever since the auto-switch went)

Retarding the timing will definitely help if you're advanced. But keeping the engine cool is not good, just like overheating it isn't. Keep it within "stock normal" operating temp for the test.

Assuming the engine is indeed in good shape, retarding the timing and running at the correct temp should be good enough.