Stuck open intake valve.
Improper valve timing.
Improper spark timing.

What year and model?

Answered by peppermrj
19 questions asked

my car is a 1999 mercury tracer with a 2.0L
its back firing through the throttle body
turns on for a couple of sec. then shots off
but while it on you can hear the valves like if theirs no oil in them

Response from casperl
3 questions asked

possibly camshaft

Answered by Lovescars
5 questions asked