Random misfiring

Tiny
RASHEED ADEOLA
  • MEMBER
  • 2005 TOYOTA 4RUNNER
  • 3.6L
  • V6
  • 4WD
  • AUTOMATIC
  • 5,000 MILES
Cylinder 1, 3 and 5 misfires simultaneously at idle.
Sunday, August 15th, 2021 AT 4:48 PM

1 Reply

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Normally when you have a misfire on all cylinders on one bank then it is something that they have in common to all of them like the coil or fuel rail but I show this engine has coil on plugs. Is that correct?

If it is then the coil is unlikely as all three of them failing at the same time is nearly impossible. So that means we need to monitor the o2 sensor data and if it were me, I would start with swapping the o2 sensors side to side.

If the misfire moves to the other side then the sensor was the issue. It appears this engine has air fuel mixture sensor which are basically the upstream sensor and then downstream as well.

I would swap both of them and just see if it moves.

https://www.2carpros.com/articles/how-to-replace-an-oxygen-sensor

If this checks out then we may have a head gasket issue on that side that is leaking compression so we need to check this as well.

Here is a guide for this:

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

Please run through this info and let us know if you have other questions and what you find.

Thanks
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Monday, August 16th, 2021 AT 6:05 PM

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