Happened this morning less than a mile from leaving home. I started truck and left, I usually let it warm up for 5 minutes or so before leaving. Really cold here the last few days, northern Michigan. Truck was definitely lurching (missing) as I drove. Reset the CEL and vehicle seemed to drive okay after. Have not had this problem before. I do have codes (p1414/p1417) for the SAI showing up every once in while...new pump???? Don't know if these 2 problems intertwine or are separate. STI wires...113K mileage.

 

Still a misfire in #4 (p0304). What should I be looking for?? Always run premium (93 octane where I live).


After I reset the codes this morning it did continue to miss but did not throw codes again...

 

P1319=Misfire detected with low fuel level


Bad injector?

 

I would tend to agree with the above post about a bad or clogged injector, but it might be worth it to pull the plug and check the plug wire for the trouble cylinder very carefully.

 

I believe the P0304 code is electrical. Get an old plug, pull the #4 plug wire, put the old plug in and check for spark. If you have no spark it could be the wire or a coil problem.

 

Have not had time to troubleshoot the suggestions, but thank you for them. This morning had a rough idle on startup. Had pending codes of p0300 (multiple misfires) 0304 and 0303. The only check engine code was the P0304. Air temp was a lot warmer that past 3 mornings, 20 degrees outside. Now that I have multiple misses showing up, what else should I look at?

 

Have you had any rich or lean codes? (1147, 1171, 0171 or/and 0174)? Mine started with misfire codes and then eventually registered the aforementioned codes which equated to a large vacuum leak that slowly grew to really throw off my idle and make more cylinders misfire. After a smoke test and replacing most of the top end hoses I dug into it and replaced the intake manifold gasket and the fuel injector o-rings. Everything was cleared up after that.

 

If it makes any difference... P0304 was the first and most repetitive code that was thrown through my 4 month saga with the vacuum leak. Maybe try a smoke test to make sure it is not a vacuum leak? (Search smoke test vacuum leak)

 

NO lean or rich codes. Will do the smoke test tomorrow. Bought a new set of plus 4's. I have no idea when the plugs were last changed...if ever. Brought this beast back from the dead in July, so not sure of service history. I plan on disconnecting MAF as part of troubleshooting. THANKS FOR THE IDEAS!!!! As always this site is helpful!!

 

I believe it's fixed...removed the spark plug cable from the #4 plug and the crimp on end of the cable stayed attached to the plug. The cable had separated at the crimp and a 3/4" long section of cable was still attached in the crimp. Stripped off the boot and re-crimped ("W" style crimper) the cable. Put cable back on the spark plug and drove for a few miles with NO MIS-FIRES codes.