checking the ignition coils?

[smughal31]

My check engine light came on, on my 2002 GMC sierra V8 5.3 a month ago. it was an o2 sensor code. well long story short i changed the spark plugs and the wires replaced the fuel filter and ran some seafoam through it and its still showing a multiple misfire code. The truck runs pretty dang good in my opinion you can just hear it miss a little bit. my thoughts are its got a bad coil pack. i just dont know/understand how to check them. any advice would help a lot and i would greatly appreciate it. these things cost a lot or i would just go ahead and replace them all anyways. lol thanks!

 

[ahyde]

YOU MAY HAVE TO DO A CRANKSHAFT VARIATION LEARN PROCEDURE WITH A SCAN TOOL.

 

[Oldman]

i have found that a crank sensor will cause this too.

 

[smughal31]

It did read crank shaft sensor once I forgot about it reading that. So that would cause a misfire ?

 

[Oldman]

i have seen it several times when i was doing it for a living.i chased a dodge van for all most a week before i found it.it came to us on roll-back.the crank sensor had been changed three times before it got to us.it would run but after the codes were cleared and it ran for a few min the check engine light would come on and show several cylinders with miss fire.got a crank sensor from crown and it fixed it.

 

[smughal31]

Dang well I will try that is it hard to change?

 

[Oldman]

no. it should be in the big pulley at the bottom of motor(center at bottom)belt goes around it.it will be held in with one or two bolts 10 or 13mm i think.(in crank shaft pulley or damper as some time called.when u get a new one look at it and you can tell where it is by looking for a sensor that looks like the new one.

 

[smughal31]

Ok I will do that either today or tomorrow thanks a lot for your help I really appreciate that!

 

[Oldman]

no problem man.

 

[digitalcb]

Similar problem here. Replaced crank shaft sensor, all three coils, plug wires, plugs and timing belt.</p>

Trouble codes went away but it didn't fix the problem but I feel better for having helped the economy emoBang </p>

Suspect a valve problem that I'll just have to live with.
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