[ZubUchiha]

1997 Mitsubishi Eclipse GST Spyder Manual
- Bone stock except for intercooler pipes and blow off valve.

Issue:

• P0300 Random Misfire (Only in gear under throttle, not when idling)
• Low voltage
• RPM gauge jumpy/bouncy under load only in gear.
• Fuel smell coming from engine bay.

Tests done:

• Compression test (180 across the board)
• Boost Leak test
• Smoke test
• Injector test
• Fuel Pressure test at return port (Will do another at the fuel pump)

Fixed/Replaced:

• Timing belt
• Valve cover + gasket

- Spark:
—> New plugs
—> New Wires
—> New Coil packs

- Air:
—> Boost leak tested 3 times
—> Smoke tested
—> Replaced Intercooler pipes because of vacuum leak
—> No other visible leak
—> New cx racing (Greddy replica) blow off valve

- Fuel:
—> Fuel pressure tested the fuel pump
—> New fuel filter
—> Tested and got new seals and pig tails for injectors

- Electrical:
—> New battery
—> Replaced alternator twice with 90 amp galant alternator. Brand is Ultima.
—> Redoing the grounds right now because car has low voltage.
—> New terminals


I don’t know what’s causing this random misfire. When it’s in gear and it misfires, I have to put the car in neutral and back into gear in order to stop the misfires and this works most of the time. I’ve also attached a screenshot of my monitors on my phone when the OBD is connected.

I need help and before anyone says to look at old posts, I have looked at quite a few, but nothing is close to what I have. If anyone has advice or can link an old post that has symptoms similar to mine, I will gladly take the help.

Thanks,
Z.

Attached is a pic of my monitors.

 

[ZubUchiha]

After renewing my grounds from battery to chassis and battery to starter, the car wouldn’t turn on and our alternator went out. We just put in another alternator, a Duralast one from autozone and the car is able to run. Voltage on the battery is almost 14 as well as the alternator. Car still has jumpy tachometer (performance is not affected when tach is jumpy/bouncy) and still has a random misfire.

 

[diambo4life]

What plugs/wires?

 

[evolved4g63t]

Did you check to make sure your injector wires and spark wires are going to the proper order? I had a similar problem but that was because injector plugs were in wrong spot causing a misfire.

 

[Chad Noles]

You might want to check your ISC ( iac valve).It can cause a jumpy idle if dirty or dead.