Random cylinder Misfire - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > Engine Tunes/Mods

Engine Tunes/Mods Performance Engine Tuning/Engine Modifications

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  #1  
Old 07-30-2011, 04:12 PM
Kevin32 Kevin32 is offline
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2002 GMC Envoy SLE
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Random cylinder Misfire

On my 2002 GMC Envoy I got a random cylinder misfire reading. I changed all six spark plugs and the crankshaft position sensor. Still runs rough though. SES light is blinking. Any ideas of what to fix next?
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  #2  
Old 07-30-2011, 05:59 PM
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RayVoy RayVoy is offline
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You probably have a bad coil.


Dozens of threads on the subject, including one, or two, on changing the coil.
Give the SEARCH function a spin.

Good luck
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  #3  
Old 07-30-2011, 09:56 PM
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GfabSabfd GfabSabfd is offline
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Ooohhhhh,just had same the same problem 6 mos ago. Multi misfire. Purchased 2 new coils,swapped one out then tested with OBDII. Kept testing until the meter told witch cylinder was misfiring. Repaired 1st and 3rd coil pack from front of truck. 1mos ago happened AGAIN! Had to change remaining 4! I bought them at several auto zone locations,cause they only stock one or two. They go for about 65-70,a piece. Truck runs awesome! Did these,new plugs,and throttle body cleaning. Truck is BEAutiful. Good luck trouble shooting, definately need a meter to isolate multi misfire code. Once ya know which cylinders are defective it is an easy fix. 10mm socket for the coilpacks and breather cover,and throttlebody.http://forums.trailvoy.com/showthrea...t=48277&page=2. This thread may help.
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  #4  
Old 07-30-2011, 10:23 PM
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petevw petevw is offline
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Quote:
Originally Posted by Kevin32 View Post
On my 2002 GMC Envoy I got a random cylinder misfire reading. I changed all six spark plugs and the crankshaft position sensor. Still runs rough though. SES light is blinking. Any ideas of what to fix next?
Most likely bad coil pack(s). Since it's a 10 yr old vehicle, I'd recommend changing all six coils......should take care of the problem. I had same issue w/ blinking SES light.....replaced all coils, problem disappeared.

BTW, what plugs did you put in it?

Oh, and double check to make sure you seated the tip of the coil pack straight down and onto the spark plug.....the coil CAN be inserted slightly crooked and not touch the plug.
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Old 07-30-2011, 10:34 PM
Kevin32 Kevin32 is offline
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2002 GMC Envoy SLE
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Random misfires

I took the clip off the Camshaft Position Actuator, and it had oil on the female end. Cant find where to buy a new one though. Or if it is even called a Camshaft Position Actuator
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  #6  
Old 07-30-2011, 10:35 PM
Kevin32 Kevin32 is offline
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2002 GMC Envoy SLE
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Quote:
Originally Posted by petevw View Post
Most likely bad coil pack(s). Since it's a 10 yr old vehicle, I'd recommend changing all six coils......should take care of the problem. I had same issue w/ blinking SES light.....replaced all coils, problem disappeared.

BTW, what plugs did you put in it?

Oh, and double check to make sure you seated the tip of the coil pack straight down and onto the spark plug.....the coil CAN be inserted slightly crooked and not touch the plug.
I put in 6 new AC Delcos.
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  #7  
Old 07-30-2011, 10:37 PM
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petevw petevw is offline
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Quote:
Originally Posted by Kevin32 View Post
I put in 6 new AC Delcos.
Which ones? Reason I ask is that these engines seem somewhat sensitive to plugs.
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  #8  
Old 07-30-2011, 10:51 PM
Kevin32 Kevin32 is offline
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2002 GMC Envoy SLE
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Plugs

Quote:
Originally Posted by petevw View Post
Which ones? Reason I ask is that these engines seem somewhat sensitive to plugs.
I put in #41-103's AC Delcos. Would changing the Camshaft Position Actuator Solenoid help too?
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  #9  
Old 09-20-2011, 10:17 PM
Gevans17 Gevans17 is offline
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where to buy exhaust cam actuator

Quote:
Originally Posted by Kevin32 View Post
I took the clip off the Camshaft Position Actuator, and it had oil on the female end. Cant find where to buy a new one though. Or if it is even called a Camshaft Position Actuator
check rockauto.com
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  #10  
Old 09-25-2011, 11:45 PM
Timmyblazer33 Timmyblazer33 is offline
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Changed All Coils

Hey guys,
I had the same problem and I changed all plugs and coils. However, I am still getting a multi random misfire. I don't know what to do?? Any Suggestions??
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