1991 Toyota Pickup HIGH SPEED MISS

SUPRA222

MEMBER
1991 TOYOTA PICKUP
6 CYL
4WD
MANUAL
140,000 MILES

Occasionally, misses at all different speeds/rpms, whether cold or hot. Drops 1500 rpm and comes back instantly causes banging on rear end. Started doing this after driving a rough wash boarded road. Been doing this for 4 year but is getting more frequent and severe in rpms drops and recovery laterly, especially since replacing the distributor. Have replace ECU, distributor, cap and button, plugs and plug wires, mass air flow sensor (MAF), spark igniter, coil, fuel filter, pulled/tapped various wires/connectors tried premium gas. Only recently I started getting a Diagnostic code of 31 (MAF), I had the same problem without code previously. Unable to clear the code even after taken battery cables off.

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Inspect and test all the following listed below and get back with some testing results we start here

Oxygen sensors.
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.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.