1995 Toyota Corolla difficulty diagnosing source of misfiri

KYHILLS

MEMBER
1995 TOYOTA COROLLA
4 CYL
2WD
AUTOMATIC
150,000 MILES

Car had been running fine with no issues, good gas mileage. Missed a few times driving down highway then died. Would not start. Something in distributor melted and had new distributor put on. It cranked and ran good except for some misfiring. Replaced plugs, plug wires, oxygen sensor but still misfiring. Checked for fuel pressure, vacuum leaks, checked timing belt. Also had local shop try and diagnose problem but they could not find out problem. The check engine light used to come on occasionally. After these current repairs it is not coming on even with all the misfiring? Misfiring is more when engine is cold and seems to occur more around shift changes(higher rpm?) Misfiring is such that it causes significant hesitation/hiccuping. It will misfire more with stronger acceleration than with light acceleration.
Any ideas?

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Hi kyhills, welcome to 2carpros and TY for the donation

One of the following below could be causing it Inspect and test all of it-

Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
False air leakage/vac leak
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.