Chasing Misfire

badandyturbo · Jan 21, 2020

Hello friends. I have been hunting down a misfire in cylinder 2 for a bit now and I need some help.

Code is P0302. Misfire cylinder 2
I have swapped coilpacks.
I have swapped plug wires.
I have replaced the spark plug.
I have replaced the injector.
I have pulled the valve cover and checked rockers.
I have used 87 octane and E85.

Truck misfire is only noticeable at temp on idle. Cold start and driving it's fine.

Any other ideas?

avalonandl · Jan 21, 2020

Head gasket or intake gasket is my "guess"

donjetman · Jan 21, 2020

Somebody here recently finally cured their misfire problem by replacing either the coil pack wire harness. See post# 36 in the following thread: https://www.tahoeyukonforum.com/threads/persistent-misfire-cylinder-3.115593/page-4

OR VietVet · Jan 21, 2020

What is the compression on that cylinder compared to the others?

Doubeleive · Jan 21, 2020

Like Ron said compression test and I would check the injector harness voltage, check all 4 connectors on that side and see if they all read the same, it's not uncommon to have a bad harness.

OR VietVet · Jan 21, 2020

Yea, if you have a compression problem, that simple basic test could have saved you all this time chasing the problem and any parts you threw at it.

badandyturbo · Jan 21, 2020

Thanks for the advice. I will do the compression test first.

OR VietVet · Jan 21, 2020

If you do that compression test be ready to do a dry and wet test. If the compression is low, compared to other cylinders, then remove that tester and spit a little oil in that cylinder to see if the compression comes up. If it does, then rings are suspect, if not, then valves or head gasket is likely.

badandyturbo · Mar 15, 2020

Ok so the compression is good. I have also used a noid light to check the injector. Its firing correctly. I am running out of options......

Doubeleive · Mar 15, 2020

maybe hook up a scanner and get a live data feed going and try wiggling the injector wire harness and see if it correlates with that. If the hardware is good then it must be electrical.

Chasing Misfire

badandyturbo

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avalonandl

Full Access Member

donjetman

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OR VietVet

Multnomah Falls

Doubeleive

Wes

OR VietVet

Multnomah Falls

badandyturbo

Full Access Member

OR VietVet

Multnomah Falls

badandyturbo

Full Access Member

Doubeleive

Wes

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