Engine runs rough after plug and wire change

[Charles Craven]

I had my plugs and wires changed by a GM dealer on my 2012 Avalanche. I noticed that it runs rough compared to before. I took it back and they hooked it up to computer and showed me it was not missing. I trust the dealer as my sister works there, but curious as to what else it could be if it looks ok on computer? I notice it much more when i first crank engine. Ideas?

Topic

[Richard Kirshy]

Lets look at the issue..
I assume the engine ran fine before the service?
If so the issue can be narrowed down to what was replaced.
Were the correct plugs installed?
Were the correct plugs gaped properly?
Were the correct wires installed?
All things being equal and nothing other than plugs and wires were changed, that is most likely the cause of your trouble.

[Brian Regner]

One of the wires may not be seated fully or a plug could be gapped incorrectly

[Author]

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