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Completely stumped

3K views 4 replies 3 participants last post by  trailblazer90 
#1 ·
I recently purchased a 2002 trailblazer, vortec 4.2L I6 LS 2WD.

I have noticed that when you are sitting at a stop, and then quickly switch back to gas and begin to accelerate it seems to lose power for a second and then take off. this was the first issue I found until I was driving in town and it began raining.

at this point in time, it began missing. when taking off from a light it is very noticeable, you can watch the rpm bounce up and down over about a 700 rpm range and a sudden loss in power, but after a few seconds it seems to stop and it takes off but it periodically returns. it seems to be at its worst at a low idle.

the problem is that there is no service engine light, and it doesn't flash during acceleration. the fan shroud is currently not on it and it could be part of the problem, but I don't know. please anything will help/
 
#3 ·
***UPDATE***
went today to buy a code reader and the book for it, once i got to town it started missing badly. it continued missing the whole way home and once there i plugged in the code reader and noticed that the service light was off but it had two stored codes p0130 and p0133 for a bad bank1 sensor1 o2 sensor. got a ride back to town and picked up the o2 sensor and went to start it so it could warm up as suggested, wouldn't start. after trying a few times it began to hit so i continued cranking. after about 15 seconds it started and went straight to around 2000rpm and stayed there. after a minute or so it idled down but once i switched into reverse it returned right back to around 2000 without ever touching the gas. after another minute or so of running my temp sensor flat lined and the check gauges light came on and the clutch fan engaged and stayed engaged. i shut it off and then had to repeat the start process. once started i noticed the temp gauge still was stuck on 100 and the battery light came on even though the amp gauge was reading slightly above 14volts. can anyone please shed some light on this, its almost christmas and most places are closed for the next 2 days.
 
#5 ·
Solved






I unhooked the battery and checked all wires under the hood to see if there was a short or bad connection. after a few minutes, I hooked the battery back up and started it and everything went back to normal. I then proceeded to not so elegantly remove the o2 sensor,and replace it with a new one. afterward there were no electrical issues and the miss was gone.
 
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