pre ignition on 1999 Ford Escort

my car knocks, even with premium gas. i have checked all vacuum hoses and cleaned the throttle body and EGR. What else can I do?

by in Houston, TX on March 23, 2009
1 answer
ANSWER by on March 26, 2009
Probably the mass airflow sensor is bad, Napa has rebuilt units available $108 to $139 plus a core charge, about 1/2 hour to replace