Engine Performance problem
2002 Chevy Trailblazer 6 cyl Four Wheel Drive Automatic 150000 miles
engine developed a miss and the service engine soon light came on. The local auto part store scaned the code and said it had a miss fire on cylender #6. I changed the fuel filter, the spark plug on #6 changed the oil and filter and the air filter. And that didn't help.
I changed the coil pack and the plug again. Still no help. I checked the compression and there is between 145 to 155 lbs on all cylenders. I replaced the fuel injector and stilll no help. If you acelrate hard the check engine light flashes, and if you are easing along it stays on solid.I have noticed that the cruise control has quit working and when the heater comes on the miss is more noticable.I have checked for a vacume leak and havn't been able to find one. Any Idea's what to try next? Thank's in advanced
Rescan the computer-is there any other code/s then P0306
Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.
February, 18, 2009 AT 6:18 PM
I just had the same exact problem with a Trailblazer when I replaced the bad coilpack I had a couple of the other coils unpluged checking them when I pluged the wiers back into the coils I accidently mixed up 2 of the wires the 4 to the 5 and 5 to the 4 thought the problem wasnt fixed thougt it was more serious took it to shop to have a compression test done and they told me what I did felt like an idiot but hey at lesat the problems solved worth a shot to check out before u spend a bunch more money