2002 Jeep GC, 4.0 Liter, 6. Getting P06 Code,(Misfire on # 6) with check engine lite, poor idle and rough running

Asked by Jan 01, 2012 at 02:54 PM about the 2002 Jeep Grand Cherokee Laredo 4WD

Question type: General

2002 Jeep GC, 4.0 Liter, 6. Getting P06 Code,(Misfire on # 6) with check engine lite, poor idle and rough running when driving it. Check plugs, little brownish-gray, checked the coil rail, no arcking on # 6 rubber boot. Inspected the coil rail assy and see no cracks, discoloring. What OHMS reading should I be getting across the 4 pins of the coil rail. Any other suggestions to look at?
Thanks,
Vince

3 Answers

3,125

Could be a bad spark plug. It's a cheap replacement, so try that first. I had one vehicle where I put new plugs in a couple weeks before. Then it started running rough. I thought it was vacuum, MAF, PCV, etc... Ended up just being a faulty spark plug.

2 of 2 people found this helpful.
Best Answer Mark helpful
1,795

Make sure the electrode is at the correct length, be careful not to mix up wires from the distributer cap, and obviously make sure they connect fully. If all else fails, loo, at the injector

Jan 2nd, 2012 Removed the coil rail assy from the car, checked for cracks, arcking, burned areas on the assy itself and found none. Checked the ohmage readings on the 4 pin connector of the coil rail assy, no auto parts store could give me what the resistance reading should be. It was a Holiday and the dealerships were closed. Checked the internet and found 3 different ohmage readings for resistance from various web sites. I didn't find any unusual readings from what I found off the internet, to give me a starting point. Checked the rubber boots for cracks, burn areas, or ware areas and found none. Checked the springs inside of the rubber boots that contact the plugs, for arching, ware, burn areas, corrosion, rust etc and found none. Cleaned out all of the old dielectric grease from the springs and boots and repacked the rubber boots with dielectric grease. Replaced the spark plugs with single spark electrode style plugs, I perviously had Bosh Platinum Dual Spark plugs. Since replacing the spark plugs, I have driven the car for about a week and have had no issues, codes or warning lites come on. It seems the fix was a bad plug on cylinder # 6. Lucky it was a cheap fix, replacing the all the spark plugs. Thanks, for you help Matt. Vince

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