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Resolved 2G Multiple Cylinder Misfire

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2gsx2tame

Probationary Member
17
0
May 9, 2003
IdahoUS
Hello, the car is a 1999 Eclipse GSX. I've been having an issue with mulitple cylinder misfires and a check engine light code "P0300".

When the engine is still kind of cold and while driving, the car will suddenly loose power and the motor starts shaking/vibrating. I'll press in the clutch and it will stop the misfiring usually. This usually happens when I am in 3rd or 4th gear at around 3000 rpm. The problem shows up with or without being under boost and seems to happen at random.

The problem first started showing up last summer (2017), about two weeks after changing the timing belts. Does anyone know what my next step should be in trying fix this? Please take a look at the following history of what's been done to the car; before and after noticing the problem. Thanks for any help!

2015
Replaced Fuel Filter
Replaced Spark Plugs

Replaced Slave cylinder
Replaced Master Cylinder
Replaced Clutch Fluid Line

2016
Replaced Cam Angle Sensor

2017
Replaced timing belts (both timing belt A and timing belt B)
Replaced Crank Position Sensor
Replaced Water Pump

Two weeks later - First noticed P0300 CEL

Found Boost/vacuum Leaks
Replaced Upper Intercooler Piping
Replaced Blow Off Valve
Replaced Seals inside Throttle Body
Replaced Throttle Body Gaskets

2018
Replaced Spark Plugs - again
Replaced Spark Plug Wires

Replaced Clutch

Replaced Before Catalytic Converter O2 sensor
 
Solution
After 4 years of having this misfire, it is finally fixed! It was a faulty crank position sensor. I learned that I will never buy a cheap part again unless it is easy to get to. The Mitsubishi cps saved the day. For those of you needing to change your cps without messing with the timing belt, I suggest bending the belt using a screw driver as leverage and feeding the connector end of the wire through first (not the sensor end).
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Have you done a boost leak test?
What psi did it hold to?
For how long did it hold?
Where did it leak?

What brand spark plugs are you running? exact part number
What are your spark plugs gapped to?
Do you have a tuning device? ecmlink?

We are assuming this is a 2.0 7 bolt split thrust engine with the revised cas on the 7 bolt head.
 
Upvote0
Yes, found and fixed boost leaks. See history above. Held at 15 psi (didn't fill past that) and I don't remember exact time it held for but pressure dropped very very slowly. I followed a guide on here and it was within specs.

Plugs = BPR6ES (NGK Copper) gapped to .028"

Wires = NGK High Performance Superior Resistor Spark Plug Ignition Wire Set - ME77

I don't have a tuning device but have an OBD II reader with the Torque Lite app.
 
Upvote0
I took it to another shop who had a scan tool and I told them what I've done to try to fix it. They suggested I replace the coil packs. After they installed new coil packs they said the problem was fixed. The next morning (yesterday) I had the same misfire problem and return of the check engine code P0300. I am loosing my mind and money trying to figure this out on my own. This whole problem started after I changed the timing belt, water pump, and crank position sensor. The reason for making those repairs is because one morning my car would not start - a check engine light told me the crank position sensor was dead. While changing the cps I noticed the balance shaft belt was snapped. I did the timing belt job myself. I followed a really good tutorial and was VERY careful to follow every detail. Is there something that I might have messed up though to cause this issue? Could the new cps sensor I installed be bad? The engine sounds great most of the time. Its only while driving that it randomly begins misfiring. Please help!
 
Upvote0
After 4 years of having this misfire, it is finally fixed! It was a faulty crank position sensor. I learned that I will never buy a cheap part again unless it is easy to get to. The Mitsubishi cps saved the day. For those of you needing to change your cps without messing with the timing belt, I suggest bending the belt using a screw driver as leverage and feeding the connector end of the wire through first (not the sensor end).
 
Upvote0
Solution
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