Random Misfire

[east302]

You can tell just enough by holding open the throttle body. If the injectors have a vinyl/rubber looking flexible wrap on them and wires at the end, then it’s been swapped to the MPFI.

MPFI:

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Stock:

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[stutaeng]

Misfires go hand-in-hand with LEAN codes. To have misfires, and RICH codes makes me very suspicious of the O2 sensors.

Fix them first.

The Evap code could be as simple as the gas cap not sealing properly--perhaps just not tightened enough. Verify with the service manual.

I agree, but too much fuel (like intermittent injector being stuck open) in the mixture can also cause missfires. Watch this video:

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Eric states the car runs really rough and has mis-fires. At minute 17:00 you can see the obvious reason why! The initial problem he's diagnosing is why the fuel pressure is not holding, so very well may not be the case for the OP. Unfortunately, OP can't do this simple check on the spider injectors, so that's why an injector balance test is required, even though he stated they have been replaced. Even new parts fail. Gotta cover all the basics first.

But I bet by looking at fuel trims and O2 and doing additional basic diagnosing one can condemn one or the other.

 

[Erik the Awful]

Check your spark plugs, wires, cap, and rotor before you go throwing any other parts at it. If cylinders 5 and 7 aren't burning, the raw fuel is going into the exhaust and so is the oxygen. Your O2 sensor will see the oxygen and richen the mixture. Now you're running rich AND misfiring.

 

[Schurkey]

it does appear that cylinders 5, and 7 which are both misfiring reflect about 150 PSI of compression. I have swapped wires and plugs from cylinders with no problems,

No chance that #5 and #7 plug wires are crossed?

"5 and 7" scares me. They're the most-likely to be damaged if the wires are crossed or if there's an inductive spark into #7.

If cylinders 5 and 7 aren't burning, the raw fuel is going into the exhaust and so is the oxygen. Your O2 sensor will see the oxygen and richen the mixture. Now you're running rich AND misfiring.

But that (misfire) tends to set a LEAN code, not a "rich" code. That's why I find it puzzling that it's got a "rich" code and misfire code.

Perhaps the codes weren't set at the same time.

And at any rate, when there's fuel-trim codes, misfire codes, and O2 sensor codes, I'd replace the O2 sensors, clear the other codes, and see what comes back.

If it really is running rich and/or misfiring, the catalyst(s) are probably toast, too.