I just bought my 96 z28 and its had the hypertech programing done to it, I read on there site its not legal in california and I went to get it smogged and it failed. Im thinkin maybe thats why. How to I program the car to factory settings or where do I take it to? (I do not have the hypertech programmer) Any help is greatly appreciated.

 

There's not much in the way of closed loop "tuning" in the Hypertech. I'd be surprised if it has any affect at all on the emissions at the conditions they use for testing.

Any mail order programmer (e.g. - Trifecta, pcmforless, etc) can return your PCM to stock settings. Or you can get JET (TunerCat) or LT1_Edit software to copy a stock file off the internet and install it. Unfortunately, the OBD-II programming tools are on the expensive side.

 

Just buy somebodies stock obd2 pcm from a car like yours for 75 bucks. You may also be able to take it to a dealership and have them reflash the pcm with all the newest updates.

I also highly doubt though that the tuning is why you failed. Can you tell us where you failed at? Was it hydrocarbons? Do you have a 160 thermostat in the car?

 

Any chance your Z has a 160 degree thermostat? that with the HPP lower fan settings could be your problem. If the car runs cooler the emissions will suffer. When was the last time a tuneup was done on the car?

 

I had a tune up on the car as soon as I bought it like a month ago. It failed everything on the emissions test, badly. And it does have a 160 degree thermostat. Ill go buy a 180 degree today, is that ok to do if i leave the hypertech programing just like it is and get a higher temp thermostat? So that may likely help? (cats are crazy expensive in CA! although that may be the problem) All help is greatly appreciated.

 

If you go to a 180* t'stat, and don't change the fan on/off temps, the fans will be running constantly, holding the temperature down, fighting the t'stat. A 180* 'stat only starts to open at 180*, and isn't fully open until maybe 200*.

What were the specific numbers on the failure - allowed vs. actual, for NOx, CO and HC's? Low combustion temps will drive NOx down and elevate CO and HC. But the difference will be relatively small. If you are running grossly over normal, and exceeding the allowable, it might not be the t'stat.

Post the actual emisison results.

 

15mph CO2: 13.70 O2:.54 HC: max51 mine169 CO: max.48 mine.67 NO: max419 mine1206

and at 25 it was basically the same......

 

Also, with the my emmision levels, is there possibly some kind of additive I can just add to my gas that will make me pass smog? or are my levels to high?