My 91 toyota tercel 1.5 has a trouble code 24. what is that? high revolutions on the engine. very accelerated...ignition timing is just right... tdc 24

Yes, you do. Also be sure and set the engine at TDC of compression stroke of # 1 cylinder. Remove crank bolt and pulley, remove timing cover...you may also have to remove the front engine mount to get the cover off. Use a jack and a piece of wood under the oil pan to hold the engine up.

How long has this been going on? Could be a bad tank of gas... do you fill up at good stations like Chevron or the cheap Mexican ones? Also if you filled up when the tanker truck was filling the station you may have ended up with a tank full of sediment; there's a lot of gunk in their underground tanks and when the tanker tops it off the filling action stirs up a lot of that ****. Try filling the tank with some high-quality 87 octane (91 will make it worse) after putting a bottle of fuel system cleaner in the tank. You should also try pulling the codes; some codes do not cause the check engine light to illuminate but are still stored by the PCM. If all else fails, go back to the basics... fuel, spark and pressure. If you can eliminate two you should be able to make your job easier.

24= Intake Air Temperature Sensor (THA) Signal. AND 14= IGNITION SIGNAL

Code 22 is the Water Temperature Circuit Open or Shorted.
Fig. 1: Trouble codes for 3E engines

Fig. 2: Trouble codes for 3E-E engines
Fig. 3: Trouble codes for 3E-E engines

Pull the plugs. Sounds like you have a bad plug or a bad plug wire. Even an engine that misses will run well at high speeds but if it's missing at idle you might have a little oil on one of the plugs. I had a 91 tercel, ran great but leaked a lot of oil which would in turn foul the spark plugs. I'm sure you either have a bad wire or plug. Wouldn't mess with the idle, not sure what state you're in but it could impact emissions testing. Best of luck m'friend!
Greg

If the crank is lined up to the mark, it is at TDC, meaning cylinder number 1 piston is at TDC.

Both cam pulleys should have marks, they just look a little different.
Here are the diagrams to help out.

there are over 200 reasons for the check engine light to come on, the gas tank cap is just one of them, this light and the problem that turned it on are most likely covered under the federal emission warranty, contact the dealer. see trouble code list below for some of the probelems that cause a check enghine light.
P1100 Map Sensor - Malfunction
P1101 Map Sensor - Abnormal
P1102 Map Sensor - Low Input
P1103 Map Sensor - High Input
P1104 Air Flow
P1105 Air Flow - Abnormal
P1106 Air Flow - Low Input
P1107 Air Flow - High Input
P1108 Fuel Pump
P1109 Fuel Pump - Abnormal
P1110 Fuel Pump - Stuck On
P1110 ETS System - Malfunction
P1111 Fuel Pump - Electrical
P1112 Manifold Differential Pressure Sensor
P1112 VGT Actuator - Malfunction
P1113 Manifold Differential Pressure Sensor - Abnormal
P1114 Manifold Differential Pressure Sensor - Low
P1115 Coolant Temperature Input - Abnormal
P1116 Boost Pressure Sensor - Malfunction
P1118 ETS Motor - Malfunction
P1119 Inlet Metering Valve Control
P1120 Electric Governor - Malfunction
P1120 Inlet Metering Valve Malfunction
P1121 APS PWM Output Circuit Malfunction
P1121 Throttle Position Input - Abnormal
P1122 Boost Pressure Control Valve
P1123 Fuel System Rich - Idle
P1123 Timer Position Sensor - Malfunction
P1124 Fuel System Lean - Idle
P1125 Fuel Press Sensor1
P1126 Fuel Press Sensor2
P1127 Fuel System Rich - Part Load
P1127 Control Sleeve Position Sensor
P1128 Fuel System Lean - Part Load
P1130 Start Solenoid- Malfunction
P1131 Injection Quantity Adjust
P1134 O2s Transition Time(B1/S1)
P1135 Injection Timing Servo
P1140 Inlet Air Temperature Sensor Malfunction
P1141 Slow Duty Solenoid- Malfunction
P1145 Main Duty Solenoid- Malfunction
P1146 Idle Co Potentiometer
P1147 Accelerator Position Sensor (ETS) Circuit
P1150 Barometric Pressure Sensor Malfunction
P1151 Accelerator Position Sensor (EMS) Circuit
P1152 Accelerator Position Circuit-Low Input
P1153 Accelerator Position Circuit-High Input
P1154 O2s Transition Time(B2/S1)
P1155 Limp Home Valve- Malfunction
P1159 Variable Induction System
P1162 High Pressure Pump & Fuel Line
P1166 O2s (B1) Control Adaptation
P1166 Limit O2s Lambda Control (B1)
P1167 O2s (B2) Control Adaptation
P1167 Limit O2s Lambda Control (B2)
P1168 O2s (B1/S2) Heater Power
P1169 O2s (B2/S2) Heater Power
P1170 ECM (Barometric Pressure Sensor)
P1171 ETS Valve Stuck - Open
P1172 ETS Improper Motor Current
P1173 ETS Target Following Malfunction
P1174 ETS Valve Stuck - Close #1
P1175 ETS Valve Stuck - Close #2
P1176 ETS Motor Open/Short #1
P1177 ETS Motor Open/Short #2
P1178 ETS Motor Power - Open
P1179 ETS Position F/B-Mismatch
P1180 O2 S1 Heater Circuit- Malfunction
P1180 Fuel Pressure Regulator - Malfunction
P1181 Fuel Pressure Monitoring
P1182 O2 S2 Heater Circuit - Malfunction
P1182 Fuel Pressure Regulator - Short
P1183 Fuel Pressure Regulator - Open
P1184 O2s No Activity (B1/S2)
P1184 Fuel Pressure Regulator - Power
P1185 Fuel Position - Excessive
P1186 Fuel Pressure - Too Low
P1187 Regulator Valve - Stuck
P1188 Fuel Pressure - Leakage
P1189 Governor Deviation
P1190 Intake Throttle Actuator
P1191 ETS Limp Home Valve On
P1192 Limp home - Target Follow Malfunction
P1193 ETS Limp Home - Low Rpm
P1194 Limp Home - TPS2 Position Malfunction
P1195 Limp Home - Target Follow Delay
P1196 ETS Limp Home - Close Stuck
P1300 Spark Timing Adjust Signal
P1300 Injector Specific Data Fault
P1300 Synchronization Error-CKP/CMP
P1301 TDC Sensor - Abnormal
P1302 TDC Sensor - Low Input
P1303 TDC Sensor - High Input
P1304 Phase Sensor
P1305 Phase Sensor - Abnormal
P1306 Phase Sensor - Low Input
P1307 Phase Sensor - High Input
P1307 Accelerator Sensor - Range/Performance
P1308 Ignition Coil.1
P1308 Accelerator Sensor - Low
P1308 Accelerator Sensor Circuit - Low
P1309 Ignition Coil.1 - Abnormal
P1309 Accelerator Sensor - High
P1309 Accelerator Sensor Circuit - High
P1310 Ignition Coil.1 - Low Output
P1310 Injection Control Circuit Fault
P1311 Ignition Coil.1 - High Output
P1312 Ignition Coil.2
P1313 Ignition Coil.2 - Abnormal
P1314 Ignition Coil.2 - Low Output
P1315 Ignition Coil.2 - High Output
P1316 Ignition Coil.3
P1317 Ignition Coil.3 - Abnormal
P1318 Ignition Coil.3 - Low Output
P1319 Ignition Coil.3 - High Output
P1320 Ignition Coil.4
P1321 Ignition Coil.4 - Abnormal
P1321 Glow Indicator Lamp - Short
P1322 Ignition Coil.4 - Low Output
P1322 Glow Indicator Lamp - Open
P1323 Ignition Coil.4 - High Output
P1324 Glow Relay - Malfunction
P1325 Glow Relay - Abnormal
P1325 Glow Relay
P1326 Glow Relay - Stuck On
P1326 Glow Relay - Short
P1327 Glow Relay - Electrical
P1327 Glow Relay - Open
P1330 Spark Timing Adjust Signal
P1331 #1 MF Signal Line Short
P1332 #2 MF Signal Line Short
P1333 #3 MF Signal Line Short
P1334 #4 MF Signal Line Short
P1335 #5 MF Signal Line Short
P1336 #6 MF Signal Line Short
P1337 #7 MF Signal Line Short
P1338 #8 MF Signal Line Short
P1340 IFS 2 Open

Look at at your idle control valve. Also could be the idle up vsv. If your not sure where these are let me know and I can help you with that.

the camshaft has a pin on the pulley side that should be at the 12:00 position and the #1 piston valves should all be closed.