Engine Misfire Due to Worn Valve Seat on Chevrolet Trailblazer

Problem Description and Possible Solution

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.

Problem Data
RepairPal Verified
Average mileage: 117,458 (54,000–215,000)
Engine affected: 4.2L 6 Cylinder
6 model years affected: 2002, 2003, 2004, 2005, more2006, 2007
52 people reported this problem
Viewing 1 - 20 of 26 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.
Cylinder 3 misfire at idle. Low compression on this cylinder
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
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..
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????
had blowby in airbox intake engine idiling rough loose or worn valve stem seats had head rebuilt solved problem
Heavy miss during cold start only gets slightly better after warm up.
2 coil packs replaced and plugs replaced. No change
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.
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.
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.
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.
Bad valve and misfire. Bad idle.
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.
check enging light elluminated checked sparkplugs and coil pack all was good still existing
misfireing no compression on #1
code reading cylinder misfire 5 took it to a mechanic said just needs tune up replace coil boot plugs no change took it to another mechanic did compression check on it said only at 50 psi said will ask if I was leaking oil or burning oil I said no then he said most likely it is a valves either it is cracked on cylinder 5 or it is g8000 just in labor plus parts if it needed a new cam and is about 8000 just in labor plus parts if it needed a new cam and valves not to mention to check the head out
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.