Looking for a bit of advice to help keep my beloved Miata on the road. It is a
1990 1.6L with 141,000 and running well (apart from the N2O).I recently failed the new CA dynometer smog test at 25 mpg with 802 ppm on N2O (limit 786), HC measures low at 38 (limit 108) and Co is 0.12 (limit 0.71). After failing I replaced the plug and wires which needed doing anyway and ran G2P fual treatment thru the tank.
On the retest the car passed the pre-test inspection with N2O at 782 ppm, but when we started the real test it started to fail again. I'm guessing N20 starts to rise as the engine or cat gets hot.
Your advise is most welcome.