Originally Posted by big john;[url=tel:23223024
23223024]They've been in use for almost 50 years. Some are very simple things and many cars don't have them because their NOx emissions are low enough. Some engines use valve overlap to introduce exhaust gas to the intake instead of using an EGR valve.
Some are quite complex and cause headaches for technicians.
I had never heard of one until more recent times. And, in my shadetree mecanic days, which ended late 90s, I was never working on anything remotely new. I did work on my 88 Nissan pickup, but not much, what with computers and all. And I might have changed the plugs in my wife’s 91 Corolla, a car that needed nothing more than oil changes and tires. The plugs got changed at 145,000 miles.