So my 2002 Jeep Grand Cherokee 4.0L with 197,000 miles started acting up. When I drove to work a few days ago about 30 miles away my car was fine. But on the way back there was this flapping noise at idle and while driving. When I accelerated my car would start to kick and shake, but when I accelerated quickly it didn’t do. The check engine light was also flashing. When I got home the codes said it was engine misfire in the second and sixth cylinder. I changed the spark plugs and that didn’t fix it. So I changed the ignition coil and I thought it was fixed, drove fine all around town. When I drove to work it was great but when I drove home the problem came back. I shut the car off and turned it back on, it was a very hard start. It was also idling really rough and almost stalled out. I turned the car back on and kept going and the problem went away. Any ideas what it could be? Please help
Could be the fuel injectors for those cylinders. Could be those cylinders are worn out. What did the plugs look like when you replaced them? What color? Black and sooty or wet and oily?
Do you know how to run a compression test? That would tell you the condition of tne engine.
No I don’t know how to run a compression test
Plugs look worn but OK. Go on Youtube and find out how to run a compression test. But I am guessing fuel injectors at this point. Maybe fuel pump. But test, don’t just replace parts hoping to fix it.
Could it be fuel injectors even though it only happens periodically?
Yes, it could be intermittent injectors. A fuel pressure and supply problem would affect all 6. Ignition or injectors could affect one or 2 or 3. Looking at the firing order, 2 and 6 don’t share a coil so the wiring to the coil pack is probably OK.
Also make sure the throttle body is clean.
You could move injectors (with new O-rings) away from #2 into, say #3 and #6s injector to #5. If the misfire follows the injectors, then that confirms a bad injector or 2. Would really help to have long-term and short term fuel trims while the SUV is warmed up.