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: 114,957 (54,000–192,000)
Engine affected: 4.2L 6 Cylinder
6 model years affected: 2002, 2003, 2004, 2005, more2006, 2007
50 people reported this problem
25 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.
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.
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????
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
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..
2005 Chevrolet Trailblazer- 4.2L 6 Cylinder88,000
Cylinder 3 misfire at idle. Low compression on this cylinder
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
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????
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.
Heavy miss during cold start only gets slightly better after warm up. 2 coil packs replaced and plugs replaced. No change
2004 Chevrolet Trailblazer- 4.2L 6 Cylinder176,000
Rough idle when engine is warm with 2 occasions stalling at a red light. The dealer just diagnosed it as burned exhaust valve on cylinder #6 and said I have to replace the whole top end as it comes as one unit with all new intake and exhaust valves - price will be $3000. Am trying to decide if it is worth it at this age or will I just find out that other expensive repairs will be just around the corner (transfer case? transmission?) have been very happy with this car but don't want to become a slave to it.
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.
Bad valve and misfire. Bad 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.
Bought it drove it hard for 10 days and emissions light came on, took it in had coio,plugs,wires done and still light on so took it back where I bought it and they sent it out and their macanic said bad valve seats or valve, thank goodness for my warranty.
2005 Chevrolet Trailblazer- 4.2L 6 Cylinder97,568
Multiple cylinder misfire depending on conditions will depend on how bad the misfire is real placed all plugs coils was ok but went back to misfire at idle only fuel pressure is good, no leaks from intake system. Any clue on why this is happening to all the 4.2 cyl heads????
2005 Chevrolet Trailblazer- 4.2L 6 Cylinder146,500
"05 TRAILBLAZER ENGINE MISS I bought this cream puff 05 TB on 3/15. I needed it for work. Should've seen the red flag when the "Used car dealer" told me he would "drop it down to $3000 from 3900 if I really wanted it". It Had the obligitory disfuntional instrument gage panel. On 9/15 It started missing on #6 2 weeks ago. I replaced the plugs but it got worse and idles very rough now with bad pickup. The Check Engine light is flashing. I'm going to put a computer tester on it to check for miss's and do a compression test but all indicators are pointing to worn/bad valves,seats. Seems the remedy is a new Head with New valves & a head gaskit. I'll let you know what I find out... (which is more than GM will do for ya)
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.
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