Engine Misfire Due to Worn Valve Seat on GMC Envoy

The engine may develop a misfire due to worn valve seats. This fault will cause the Check Engine Light to illuminate. Replacement of the cylinder head may be required to correct this concern.

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Average mileage: 103,857 (57,000–253,425)
Engines affected: 4.2L 6 Cylinder, 5.3L V8
5 model years affected: 2002, 2003, 2004, 2005, more2006
35 people reported this problem
23 people shared problem details
2005 GMC Envoy- 4.2L 6 Cylinder77,000
My check engine light came on. I took my car to a local mechanic and had it checked out, the mechanic plugged his device in my car and it read misfire in cylinder #4. The mechanic looked further into the problem and found out that cylinder #4 read a low 70lbs of compression and cylinder #3 has 120lbs of compression. He explained to us that the low cylinder compression was the reason why our car shakes while idling and runs rough when accelerating. He advised us to buy a new car or get a new engine.
2005 GMC Envoy- 4.2L 6 Cylinder80,000
Cylinder 5 misfire , Pepboys said it needs a valve job , for $3400 and now GMC dealer says the head is leaking and it needs a new head, possibly a cracked head?, I read that this is a common problem and GM has changed this head five times so far, so they are prob trying charge me for a new version head and a vale job , $3500 to $4000, this car is way too new for this kind of problem, I don't tow anything with the Envoy or drive it hard, my wife actually drives the kids to school in it. There should be a recall on this problem, instead of keeping it quiet and letting the customer pay for this, I'm not sure what to do, but I know I won't buy another GMC.
2005 GMC Envoy- 4.2L 6 Cylinder57,000
misfire cylinder one, check engine on, "turn engine off" warning sign. no pressure. car white cloudy smoke, irregular idle, loss of power. warranty expired.
2005 GMC Envoy- 4.2L 6 Cylinder135,000
engine idles to rough told it was a cylinder misfire what does it involve is it expensive
2005 GMC Envoy- 4.2L 6 Cylinder135,000
My engine has a blinking light on. mechanic says its the cylinder 1 has no compression that's why the truck is misfiring. I don't understand the truck was running perfectly until a cold day came through and I turned it on. it was making a loud clicking noise.
2004 GMC Envoy- 4.2L 6 Cylinder117,000
Engine misfire at cyl 6. New plugs, etc., cleaned injectors, replaced intake manifiold gasket. No change. Removed head and had a burned exhaust valve at cyl 6.
2005 GMC Envoy- 4.2L 6 Cylinder80,000
i have a 2005 envoy with 80K miles, #3 cylinder has 50 Lbs of compression, guess im pulling the cylinder head....
2004 GMC Envoy- 4.2L 6 Cylinder65,000
Misfire cylinder 6, dealer (Chevrolet) charged me over $1000 on repairs before diagnosing problem, Now wanting $2612 to repair bad valve.
2006 GMC Envoy- 4.2L 6 Cylinder88,000
I have a check engine light. I took it in a found out that it is my valve. Cant fix it right now. Driving minimal.
2005 GMC Envoy- 4.2L 6 Cylinder190,000
Shake when driving slowly or stopped. Put on scanner showed #6 not firing. Changed plugs, coil packs, and injectors. Now it worse. Not fixing it yet.
2005 GMC Envoy- 4.2L 6 Cylinder253,425
#3,4 & 6 low compression # 4 the lowest 90lbs
2004 GMC Envoy- 4.2L 6 Cylinder160,000
The engine began developing a vibration at idle speed, especially while in gear. The Check Engine light is on and the only code that shows is a misfire in cylinder 5. Further diagnosis shows that cylinder's compression is 65 psi. I've had estimates of $2,000- $2,500 to fix the problem. The mechanics see pretty sure the low compression is a valve issue. I love the vehicle, but am not sure I want to risk the repair.
2005 GMC Envoy- 4.2L 6 Cylinder
Multiple misfires
2002 GMC Envoy63,000
engine missing. problem was # 6 cylinder not firing. turned out to be valve and valve seats on head. Had to replace cylinder head.
2005 GMC Envoy- 4.2L 6 Cylinder
i have the check engine all the time even if fifed it , it comes back
2005 GMC Envoy- 4.2L 6 Cylinder92,000
cylinder 5 misfire, stalls at lights , I replaced coil packs and all plugs , rough idle still
2004 GMC Envoy- 4.2L 6 Cylinder71,180
idle rough, check engine light. no. 3 cyl 70 lbs compression. pulled head burnt valve
2005 GMC Envoy- 4.2L 6 Cylinder68,500
Cylinder 5 has only 115 lbs and I have the rough idle
2005 GMC Envoy- 4.2L 6 Cylinder110,000
Engine check light came on. After inspection, engine needs a valve job. I was told this is a design problem with many Envoys with same engine needing this fix.
2005 GMC Envoy- 4.2L 6 Cylinder90,000
Was told that it needs a cylinder head . Misfire on #3 has been coming up. Had checked out many times . They thought it was Fuel injectors. at first . Then diagnosed with losing compression on 2 cylinders.
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