Code PO304

DWSPARKY

MEMBER
1997 MERCURY TRACER
4 CYL
FWD
AUTOMATIC
139,000 MILES

1997 mercury tracer: code po304 Runs rough intermittenly and it is hard to start sometimes. Replaced egr componets, plugs and wires, checked compression ok until code appears. Replaced all vacume hoses. Replaced intake manifold gaskets and that took care of a tapping noise. Still have the same problem po304 Intermittenly. Sometimes the check engine light will clear it self. Put a new fuel pump and fuel regulator. Fuel psi now with key on 40 psi and started 32 psi. I would just junk this car but it is my my daughters car and she is in college. Would like to get this car through a couple more years.I do most of the work myself.

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

P0304 Misfire at cylinder no.4 -try checking the sparkplug, compression and injector on it-

Was this

answer

helpful?

Yes

No

Saturday, March 19th, 2011 AT 5:03 PM

TRACERCHUCK

MEMBER
8 POSTS

Injector number four. Get car in air. Safely. Pull the injector rail (hoses, etc). Injector comes out from below. Get the book for this procedure. Takes 1.5 hour. Also replace the rubber PVC elbow at the top of the engine. If original, guarantee it is collapsed. You are welcome. Unless you want to replace the muffler, door regulators, compression hinges, etc. P>S> intake manifold won't take care of that tapping noise -- these cars have roller lifters that don't like any dirt. I would tell you how to find the one bad lifter but I need to go reprimer the jeep.