Chevrolet Repair: Engine Misfire on a Vortec 4200, hairline crack, vacuum hoses

Question
I am experiencing a misfire on the #6 cylinder on my 2002 Trailblazer with 52,000 miles.

I have switched the ignition coils, changed the spark plugs, and replaced the fuel injector.  None of these have corrected the problem.

What else can I try to correct this problem?

Thanks in advance for all your help.

Answer
Oxygen sensors can cause mis-fires. Do you have ant DTC's (Diagnostic Trouble Codes) or is the service light on the dash illuminated all the times or illuminates occassionally ?.

Loose/ cracked/ broken or incorrectly installed vacuum hoses can also cause this condition.

leaks around the throttle body and intake.

faulty and or corroded GROUND circuits for the vehicles computer.

Exhaust restriction.

fuel contamination.

an intermittent faulty spark plug wire.

hairline crack in the distributor cap.


Any of the above can be can also be caused by being what is called HEAT SENSITIVE of which causes intermittent faults in components when engine temperatures are high and or at normal operating temperature.


You have alot of things to check out.


What mechanical work or ANY kind of work has been performed on the vehicle recently ?. As most problems that occur after a recent repair was made can be traced back to the area of where the repair was made as a vacuum line may have been knocked loose or a wire connection came loose, Look around in the area where work was performed.


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