My uncle has a 98 GTP, and it has some problems with misfiring, and hard starts. Here are his codes:
P0303: Cylinder 3 Misfire
P0336: Crankshaft Position Sensor A Circuit Range/Performance
P0420: Catalyst System Efficiency Below Threshold (Bank 1)
P0440: Evaporative Emission Control System
P1404: EGR Valve
Here are my suggestions:
P0303: Checked Fuel, and spark both fine. My guess is it is caused by the CKP sensor code.
P0336: I logged it the misfire count after driving 10 minutes:
Cylinder 1: 1
Cylinder 2: 4
Cylinder 3: 2015
Cylinder 4: 400
Cylinder 5: 12
Cylinder 6: 1
I think the Crankshaft positioning sensor is causes the missing, but its really taking a toll on cylinder 3.
P0420=Clogged cat: When he bought the car, I noticed when I gave it full throttle. The rpms wouldn't go past 4k, and it stuttered and made some wierd noises. I thinking the cat it clogged nearly shut.
My Scenario: The CKP sensor went out. Thus causing these misfires. The misfires heated the cat up, thus making it kill itself.
What you guy think. Is my diagnostics right?
