1993 Toyota Corolla Surging

CONFUSEDMECHANIC

MEMBER
1993 TOYOTA COROLLA
4 CYL
FWD
AUTOMATIC
195,000 MILES

My 93 toyota corolla 1.8 is having surging problems. I have tested the fuel pressure and it is getting plenty of pressure. The cars idle will go up and down in "P" or "N" when I put it in drive and step on the pedal it try's to choke out, then when driving it surges.

I have replaced the fuel pressure regulator, TPS, IAC, 02 sensor, tune up, tested the coil in Distributor, checked and fixed vacuum leaks, Replaced the Computer, fuel filter, compression test, coolant pressure test and I am out of ideas please help.

3 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Surgng, hesistating and stumbling check and test the following:

Oxygen sensor
Catalytic converter
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires