Why is it that over revving results in more black smokes? Is it a good standard for smoke test to over rev? I own a 1 year and 5 months Mitsubishi Montero Sport with 13,000 kilometer mileage. Also, a Mazda BT-50 6 months old with 5,000 km mileage. Both failed the smoke emission tests! At normal revs of around 1000-2500, very minimal smoke comes out. We even barely use 2500+ RPM when traveling long distances including uphill climbs and minimal smokes comes out. Now, when we volunteered for smoke tests, they told us that it has to be revved at 4000! Since the equivalent displacement for smoke tests says so. Surely as it is, black smokes instantaneously came out. At 8 attempts, the smoke became less but minimal difference. We complained because our cars are barely new, with minimal mileage. We had regular oil change at 5K intervals from the car manufacturer itself. But why is it still that we failed? Is it relational to the over revving done? What are the effects of over revving? Thank you.

I did asked them why use so high RPM if under normal or even loaded driving, we barely use 2500+. They said that it is based on the model and displacement. They showed me a graph of what revolution must be used on different displacements. Also, it is ironic that they use a higher standard for new cars. In old cars, 3.5 is passing but on new cars it has to be 2. So even if the new car emits much lower smoke, it fails. How ironic. My additional question is, does fuel quality or octane level affects smoke emission? Higher Octane for higher compression only? Thank you. I did asked them why use so high RPM if under normal or even loaded driving, we barely use 2500+. They said that it is based on the model and displacement. They showed me a graph of what revolution must be used on different displacements. Also, it is ironic that they use a higher standard for new cars. In old cars, 3.5 is passing but on new cars it has to be 2. So even if the new car emits much lower smoke, it fails. How ironic. My additional question is, does fuel quality or octane level affects smoke emission? Higher Octane for higher compression only? Thank you.

Your Car smoking can be caused by a few things.. If you want to get it to stop smoking, there are Additives that you can put into your OIL to stop it from smoking. RESTORE 8 CYLINDER has worked well before for a few of my customers (even if it is a 4 Cylinder, use the 8 Cylinder). If you want to CLEAN your Engine, then Adding SEA FOAM to your Fuel, will celan everything... Will Octane Improve Performance? Yes, but many think it is not worth the Expense... If you are trying to get it to Pass, then try anything you can Your Car smoking can be caused by a few things.. If you want to get it to stop smoking, there are Additives that you can put into your OIL to stop it from smoking. RESTORE 8 CYLINDER has worked well before for a few of my customers (even if it is a 4 Cylinder, use the 8 Cylinder). If you want to CLEAN your Engine, then Adding SEA FOAM to your Fuel, will celan everything... Will Octane Improve Performance? Yes, but many think it is not worth the Expense... If you are trying to get it to Pass, then try anything you can