Code P0306 and a misfire on cylinder six?

Tiny
AROBTAYLOR
  • MEMBER
  • 1997 FORD F-150
  • 4.6L
  • V8
  • 2WD
  • MANUAL
  • 137,000 MILES
I have a P0306 code.

I have new spark plugs and swapped spark plugs.

I have new plug wires and swapped plug wires.

I swapped fuel injectors.

I did a paper test on the tail pipe with no suction. (Good sign)

I have new coil packs and swapped coil packs.

Idle changes when injector is unplugged.

I had the harmonic balancer fell off and put a new one on before the check engine light. Check engine light came up about 80 miles later.

I'm looking for some advice or direction on this misfire.

Thanks!
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Monday, May 3rd, 2021 AT 11:40 AM

4 Replies

Tiny
KASEKENNY1
  • EXPERT
Wow. Excellent process of elimination. Plus the paper on the tailpipe shows you are "old school." So for the benefit of those that are reading this that don't know that trick, it is to test for a valve issue on the exhaust side.

If the paper is pulled into the tailpipe then you have a valve hanging open and the suction of the stroke will pull the paper in.

We still need to test for an intake valve issue so we need a vacuum gauge on the engine and let it run.

Also, we need to perform a compression check.

https://www.2carpros.com/articles/how-to-test-engine-compression

Lastly we need to monitor the o2 sensor data to see if we have a rich or lean condition. So hopefully your scan tool can monitor this.

If we have neither rich or lean, then I suspect the balancer issue will come into this.

Have you inspected the tone wheel for cracks in the teeth?

Also, below is a chart that will help with vacuum gauge readings but if you can get a video of the gauge, that will as well.

Let us know what questions you have on this. Thanks
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Tuesday, May 4th, 2021 AT 4:08 PM
Tiny
AROBTAYLOR
  • MEMBER
I did a compression test. I hit around 180 PSI in each cylinder after roughly 3 out of 8 turnovers - no loss of pressure.

To clarify, my balancer didn't fall off from the crankshaft. The pulley fell apart at the rubber seal.

I will be testing vacuum pressure today and maybe the tone wheel check as well.

Photos/videos will be attached.
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Wednesday, May 5th, 2021 AT 6:58 AM
Tiny
AROBTAYLOR
  • MEMBER
Here are the vacuum test results and freeze frame data.
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Wednesday, May 5th, 2021 AT 11:58 AM
Tiny
KASEKENNY1
  • EXPERT
No issues with vacuum. Short term is slightly rich but that would not effect just cylinder 6.

Anything turn up with the tone wheel?
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Wednesday, May 5th, 2021 AT 8:05 PM

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