Having Misifiring issues codes are P0307,P0308

[arung19]

Hi guys any one can help ,having issue with misfiring codes are P0307,P0308,...checked injectors are ok,checked plug plugs are black darken....coils are also fine...every spark plug getting current ....

Edited October 23, 2021 by arung19

[paulo57509]

1. What injector tests were run?
2. Have you performed a fuel pressure leak down test?
3. What coil tests were done?
4. Are all the plugs black or just no's. 7 and 8?

[arung19]

Injectors send for testing and clean up ....was done good .

Put new spark plug ....

Coil getting spark...tested 

All the plug are coming black

Computer pull out the codes P0307 and P0308

[paulo57509]

https://www.engine-codes.com/p0307.html

https://www.engine-codes.com/p0308.html

Black plugs - either you have injectors that have incorrect dwell time (due to getting incorrect input from sensors) or a weak ignition.  Cap/rotor and/or plug wires?

[Jeremy M.]

I'd eliminate the coils being the problem by switching them over to other cylinders and seeing if the misfires move as well. Check that the spark plug's gap is set correctly (1.1 mm), check for compression (spec is 142 minimum PSI 178 nominal PSI- you can rent a compression tester free at most auto parts stores), and check that there is no source of a vacuum leak, especially towards the back of the intake, since that's where both 7 and 8 are located. I'd also check the spark with an in-line spark tester to see how strong the spark is. A strong spark should be blue-ish in color and easily visible in daylight.