99 Tahoe. Cylinder 6 Misfire....
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Joined: Nov 2008
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From: Bowie, MD
115 sounds a little low but still could be ok.Check another cylinder to make sure the problem is not you gauge and complete the equation below. However if the problem is with the fuel injector the cylinder could be washed causing low numbers. . Add 3-4 caps full of motor oil into the cylinder through the spark plug hole, disconnect the fuel injection plug in the center of the intake bump the engine around a few times (at least 2 revolutions) by taping the key then crank it like you were staring it. Now recheck the compression. If the number goes up and or is close to the same as the other cylinders you most likely have a fuel injector problem which is very common (the system was updated). If the number is low then you may have an internal engine problem.
The minimum compression in any one cylinder should not be less than 70 percent of the highest cylinder. No cylinder should read less than 690 kPa (100 psi). For example, if the highest pressure in any one cylinder is 1035 kPa (150 psi), the lowest allowable pressure for any other cylinder would be 725 kPa (105 psi). (1035 x 70% = 725) (150 x 70% = 105).
The minimum compression in any one cylinder should not be less than 70 percent of the highest cylinder. No cylinder should read less than 690 kPa (100 psi). For example, if the highest pressure in any one cylinder is 1035 kPa (150 psi), the lowest allowable pressure for any other cylinder would be 725 kPa (105 psi). (1035 x 70% = 725) (150 x 70% = 105).
Until you do this there is nothing else I can help you with
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I've seen some plugged injectors on some port injection but yours isn't that type correct?
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