Engine Misfire Due to Worn Valve Seat on Chevrolet Trailblazer

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: 106,500 (54,000–187,670)
Engine affected: 4.2L 6 Cylinder
6 model years affected: 2002, 2003, 2004, 2005, more2006, 2007
40 people reported this problem
21 people shared problem details
The truck began to have a noticable misfire and the "Check Engine Light began to blink, replaced coil packs and spark plugs on all cylinders. Still misfiring, engine light alternates between blinking and staying on.
11 people like thisFlag inappropiate
misfire in #6 cylinder. replaced fuel injector, coil, spark plugs. inspected by 4 mechanics and agree vehicle needs valves replaced. lowest quote is $1800. I know of 3 other Trailblazer owners that have or is experiencing the same thing.
6 people like thisFlag inappropiate
2005 Chevrolet Trailblazer- 4.2L 6 Cylinder95,621
Engine mis fire code for cyl #2--leakdown compression check showed #2 at 15% and 200 psi, #3 at 15% and 190 psi Dealer removed and had valve job done on it, adv replaced 9 broken bolts in the process. No help from GM on this cost me $2380.67 !!! No hard driving with this veh and changed oil every 4 to 6 thousand miles, what gives????
5 people like thisFlag inappropiate
2005 Chevrolet Trailblazer- 4.2L 6 Cylinder69,000
I have a burned exhaust valve in the engine. I have not had it repaired yet but I'm sure it is a valve seat issue and a known defect.
5 people like thisFlag inappropiate
2004 Chevrolet Trailblazer- 4.2L 6 Cylinder113,000
had blowby in airbox intake engine idiling rough loose or worn valve stem seats had head rebuilt solved problem
4 people like thisFlag inappropiate
2006 Chevrolet Trailblazer- 4.2L 6 Cylinder146,000
Misfire in the engine, check engine light displayed...Spark plugs, coil packs replaced only to need deep diag. done at Chevi place and #2 cylinder bad...Need NEW MOTOR..
4 people like thisFlag inappropiate
2005 Chevrolet Trailblazer- 4.2L 6 Cylinder95,621
Engine mis fire code for cyl #2--leakdown compression check showed #2 at 15% and 200 psi, #3 at 15% and 190 psi Dealer removed and had valve job done on it, adv replaced 9 broken bolts in the process. No help from GM on this cost me $2380.67 !!! No hard driving with this veh and changed oil every 4 to 6 thousand miles, what gives????
4 people like thisFlag inappropiate
gas gauge not working, hard miss on #6, no one can figure out what is wrong-code says coil, injector, knock sensor, all have been replaced still hard miss
4 people like thisFlag inappropiate
2005 Chevrolet Trailblazer- 4.2L 6 Cylinder88,000
Cylinder 3 misfire at idle. Low compression on this cylinder
2 people like thisFlag inappropiate
Heavy miss during cold start only gets slightly better after warm up. 2 coil packs replaced and plugs replaced. No change
1 person likes thisFlag inappropiate
Bad valve and misfire. Bad idle.
I had a mis fire on # 6 mechanics say drive it til it quits. Well about 4 weeks ago was driving and start to slow down and turn and I hear a pop then I had a vary bad vibration and my service light started flashing. My husband took it in and they the Chevrolet dealership where I bought it said I have the mis # 6 is worse and have a mis on #3 and #4.. and my motor monts are warn
2006 Chevrolet Trailblazer- 4.2L 6 Cylinder79,000
Replaced ignition coil, lasted about a year. Same problem again, dealer said failed leak down test. Recommended to change cylinder head at $3400.
2005 Chevrolet Trailblazer- 4.2L 6 Cylinder140,000
No compression in cylinder caused by worn valve seats.
2006 Chevrolet Trailblazer- 4.2L 6 Cylinder80,000
clyinder 4 misfire at idle
Engine had a misfire blinking ses light dealer says no compression on cylinder 1. cylinder does not hold on leak down test. Dealer says valve job needed. $2400 to repair. Oil was changed every 3000 to 4000 miles only mid grade fuel used. I have 130,000 miles on it. Im going back to Fords.
2007 Chevrolet Trailblazer- 4.2L 6 Cylinder94,259
Check engine light came on. Mechanic's diagnostic was valve #1 had to be replaced. Had it replaced but check engine still came on, now i find out that the whole cylinder head has to be replaced.
2006 Chevrolet Trailblazer- 4.2L 6 Cylinder63,000
Actually is in the shop now. The check engine lite kept illuminating. Was still under 30 day warranty thank god for that.the dealer replaced two coil packs and the thermostat also pulled the pcm and froze it in the freezer overnite. Still had some sort of misfire. So they pulled the head and are having it sent to a machinist to check for worpped issues. Or to replace it.wish i had never purchased this trailblazer.
2005 Chevrolet Trailblazer- 4.2L 6 Cylinder67,000
I have a 2005 trail blazer with the same problem but in cylinder 5.
check enging light elluminated checked sparkplugs and coil pack all was good still existing
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