Injector circuit open error code PO202 and PO302

HESTERMAN

MEMBER
2001 JEEP GRAND CHEROKEE LAREDO
4.7L
V8
4WD
AUTOMATIC
13,000,000 MILES

Vehicle running a little rough continued to drive and within a week it became so rough it rattles the window gets worse when I hit around 50 mph. Cylinder five misfire changed spark plugs five okay then six shows misfire. Put on new coil misfire moved to cylinder two, now have 202 and 302 code errors. Installed new injector resistance is 18, have pulse and power when checked with test light changed harness connector to injector. Has a smell of fuel when started and that cylinder spark plug although new when checked again for correct gap thinking maybe it got bumped and changed. When installed had dark black build up on it. Also when I pulled cylinder five plug during the replacement of all the plugs the porcelain was broken but the piece was wedged inside the top and was not missing any pieces that I could tell. My knowledge of auto repair is limited I get most of my information from YouTube or Haynes repair book, but problem remains unchanged. I would really appreciate any suggestion you might be able to offer me. Thanks, Dean

1 Reply

STEVE W.

MECHANIC
13,443 POSTS

Welcome to 2CarPros.
First thing I would do is swap the #2 coil to a different cylinder to verify that the coil is actually good. Those coils are a known failure item, and try to use OEM if possible, the aftermarket ones don't seem to last very well on the 4.7 or it's little brother the 3.7. As you move the coil look at the connector pins, they can get bent or corroded easily. If the misfire moves with the coil, you have a bad coil. You checked for the coil power and control so that shouldn't be the issue but the harness side plugs on those are known for the pins inside failing, by opening up from heat. If the miss doesn't move with the coil those would be the next thing to check.