1999 Mercury Cougar Q&A
1999 Mercury Cougar Question: will it hurt my car to drive 1800 miles with the EGR needing replaced soon?
EGR reduces harmful polluted emissions and prevents detonation by reducing cylinder temperatures. If you don't hear "pinging" under load you are most likely OK. For piece of mind you could use the next grade up of gas, higher octane decreases risk of knock. - patrick mannion
my cougar did the same and i changed the egr valve. the course of my problem was actually not bad after i found out what happened. the upper intake manifold was clogged up from the ethonal gas. older cars are not made for it. such as the 99. so i cleaned it and im at 150 thousand with not one problem any longer. - LUTZY