Racing idle speed

hot or cold. ? engine?
what year.?
what engine.?
what transmission, my guess is the A/T (with M/T the clutch is engaged and far safer car, as such)

my 3 jeeps with 4.0 all loved to race the idle. all M/T so is my 08
the ISC loved to stick, (PCV/EGR black cloud of death caused)

Some jeep engines, that are SPEED DENSITY based.
that is a MAP sensor not MAF based.
will race for the following reasons (all are classic and common)
1; any air leaks to the plenum. (aka Induction vacuum leaks)
2: ISC stuck open and jammed.
3: TPS bad.

The ECU knows its racing for sure. RPM.
and is for sure trying to lower RPM,
but cant, for all the reasons above.
that is how it all works.
The iSC is the idle speed control servo system.

the tests are easy, but takes tools.
got tools?
if not??, its , SHOP TIME.

hot engine ?, cold or both,, EFI runs in 3 modes, cold ,warm and hot.

name it.

which engine option (displacement)??????



there is no idle adjust, that is the PCMs, job 100%, all the time.

Carbs are gone.

here is rule one for all EFI.

idle is the last thing to work correctly.

anything the causes a gross imbalance of engine power to engine load, under idle will cause , idle controls to fail.



low idling causes. (over 50 but, here ar basics)

1: AFR (air fuel mixture too lean) usually surges. (clogged or leaking injectors. or fuel pressure way to high)

2: air leaks, cause racing, so not that. (speed density car ,if is)

3: egr stuck open. low idle and misfire.

4: ISC stuck closed (IAC electric)

5: cam belt slipped, timing retarded, compression at 1/2 spec, and well, valve will bend soon....

6: CEL glowing running? can be in limphome, limp cancels Idle controls (in may cases) RTM read the FSM on DTCs.



if fails hot?, is hot = 180F temp or more? "thermometer time"

if not, the PCM goes , quite nuts.

hunting or surging ilde. name the 2 RPMS, low and high , is it hot or cold engine this issue.? 400rpm or 1000 or 2000 all are diff.causes.
no year, stated. so cant help.
but ill answer in the generic,
1: the ECU (got a carb,? )
the ecu controls idle speed at all times.
if not , there is a problem (you)
A: air leaks in the induction will make motor race at some point the ECU/ISC loses control. and hunts. trying hard to correct it.
b: egr stuck open idle too low, iSC cant correct it,, bad EGR.
c: engine EFI running way too leak starving for fuel so it hunts for 2 reasons < ISC hunting, and lean does that.
lean is gross power loss and opening throttle bogs the engine.
so is double bad. ISC makes it worse,

all this breaks down to 2 reasons.
1: ISC bad. in some way (gummed up. or restricted inside)
2: bad fueling or air leaks. vacuum leaks.

try answers , the hot cold question and the 2 speeds, of the hunt.
lowest rpm and highest of the hunted range of RPM.

A faulty egr would not create a high idle issue. if an egr valve were to open while idling then it would create a heavy stumbling engine or it would die right out. if there is a check engine light on (or service engine soon light) have the codes pulled. Failing that then I suggest taking it to a reputable shop

Here is a code list for you. Remember this doesn't always mena a sensor issue, the problem can be in the wiring as well, or in the case of a lean code you may have an actual lean condition due to a vacuum leak at the intake or vacuum hoses or connections. I have highlighted your fault codes and added extra notes.
GM common codes for OBD1 (for vehicles made before 1995)
12 System normal
13 oxygen sensor circuit open
14 coolant sensor high resistance or shorted
15 coolant sensor circuit low or open
16 direct ignition system (DIS) fault in circuit
17 cam position sensor fault
18 crank or cam sensor error
19 crank sensor circuit fault
21 tps sensor out of range
22 tps sensor signal voltage low
23 intake air temp sensor out of range, low
24 vehicle speed (vss) sensor circuit fault
25 air temp sensor sensor out of range, high
26 quad-driver module (computer) circuit #1 fault
27 quad-driver module (computer) 2nd gear circuit
28 quad-driver module (computer) circuit #2 fault
29 quad driver module (computer) 4th gear circuit
31 camshaft position sensor fault
32 egr circuit fault
33 map sensor signal out of range, high
34 map sensor signal out of range, low
35 idle air control sensor circuit fault
36 ignition system circuit error
38 brake input circuit fault
39 clutch input circuit fault
41 cam sensor circuit fault, igntion control circuit fault
42 electronic spark timing (EST) circuit grounded
43 knock sensor malfunction or electronic spark control (ESC) circuit fault (ignore this for now)
44 oxygen sensor lean exhaust (make sure you no engine vacuum leaks)
45 oxygen sensor rich exhaust
46 pass-key II circuit or ps.pressure switch circuit fault
47 pcm-bcm data circuit
48 misfire diagnosis
51 calibration error, mem-cal, ecm or eeprom failure
52 engine oil temperature circuit, low temperature indicated
53 battery voltage error or egr or pass-key II circuit
54 egr system failure or fuel pump circuit low voltage
55 a/d converter error or pcm not grounded or lean fuel or frounded reference voltage
56 quad-driver module #2 circuit
57 boost control problem
58 vehicle anti-theft system fuel enable circuit
61 a/c system performance or degraded oxygen sensor signal
62 engine oil temperature high temperature indicated
63 oxygen sensor right side circuit open or map sensor out of range
64 oxygen sensor right side lean exhaust indicated
65 oxygen sensor right side rich exhaust indicated
66 a/c pressure sensor circuit low pressure
67 a/c pressure sensor circuit or a/c clutch circuit failure
68 a/c compressor relay circuit failure
69 a/c clutch circuit head pressure high
70 a/c refrigerant pressure circuit high
71 a/c evaporator temperature sensor circuit low
72 gear selector switch circuit
73 a/c evaporator temperature circuit high
75 digital egr #1 solenoid error
76 digital egr #2 solenoid error
77 digital egr #3 solenoid error
79 vehicle speed sensor (vss) circuit signal high
80 vehicle speed sensor (vss) circuit signal low
81 brake input circuit fault
82 ignition control (IC) 3X signal error
85 prom error
86 analog/digital ecm error
87 eeprom error
99 power management

Well.... Here is a full list of the codes I can find that Kia list. Oddly it jumps from P0120 to P0122

I hope the attached will help, but you may need to talk to your dealer.


Diagnostic Codes
Kia
Without Onboard Diagnostics (OBD-II)
2 Distributor no Signal.
3 Distributor G Signal.
7 Fault on SGT Signal.
8 Mass Air Flow Sensor.
9 Engine Coolant Temperature Sensor.
10 Intake Air Temperature Sensor.
12 Throttle Position Sensor.
14 Atmospheric Pressure Sensor.
15 Oxygen Sensor.
16 EGR Valve Position Sensor.
17 Feedback System.
18 Injector No. 1 open or short.
19 Injector No. 2 open or short.
20 Injector No. 3 open or short.
21 Injector No. 4 open or short.
24 Fuel Pump Relay open or short.
25 Pressure Regulator Control Solenoid Valve.
26 Purge Control Solenoid Valve.
28 Solenoid Valve (EGR) open or short.
34 Idle Speed Control Solenoid Valve.
35 Deteriorated Injector.
36 Deteriorated Air Flow Sensor.
37 Intake System Air Leakage.
41 Variable Inertia Charging System Solenoid Valve.
46 A/C Cut Relay open or short.
48 Power Stage Group 1 Malfunction (inside ECM). Injector 1-4 Purge Solenoid Valve, EGR Solenoid Valve or Damaged Power Stage.
49 Power Stage Group 2 Malfunction (inside ECM). Idle Speed Control Valve Failure or Damaged Power Stage.
56 Idle Speed Control Valve Closing Coil open or short.
57 A/C Compressor Input Signal short.
73 Vehicle Speed Sensor open or short.
87 Malfunction Indicator Lamp short Circuit.
88 ECM Data.
99 Battery.





OBD-II

P0100 Mass Air Flow or Volume Air Flow Circuit Malfunction.
P0101 Mass Air Flow or Volume Air Flow Circuit Range/Performance problem.
P0102 Mass Air Flow or Volume Air Flow Circuit Low Input.
P0103 Mass Air Flow or Volume Air Flow Circuit High Input.
P0107 MAP/BARO Circuit Low Input.
P0108 MAP/BARO Circuit High Input.
P0110 A/T Circuit Malfunction.
P0115 Engine Coolant Temperature Circuit Malfunction.
P0116 Engine Coolant Temperature Circuit Range/Performance Condition.
P0117 Engine Coolant Temperature Circuit Low Input.
P0118 Engine Coolant Temperature Circuit High Input.
P0120 Throttle Position Malfunction - Circuit A.
P0122 APP/TPP Sensor Switch Low Input - Circuit A.
P0123 APP/TPP Sensor Switch High Input - Circuit A.
P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control.
P0130 Oxygen Sensor Circuit Malfunction - Bank 1 Sensor 1.
P0131 Oxygen Sensor Circuit Low Voltage - Bank 1 Sensor 1.
P0132 Oxygen Sensor Circuit High Voltage - Bank 1 Sensor 1.
P0133 Oxygen Sensor Circuit Slow Response - Bank 1 Sensor 1.
P0134 Oxygen Sensor Circuit No Activity detected - Bank 1 Sensor 1.
P0135 Oxygen Sensor Heater Circuit Malfunction - Bank 1 Sensor 1.
P0136 Oxygen Sensor Circuit Malfunction - Bank 1 Sensor 2.
P0137 Oxygen Sensor Circuit Low Voltage - Bank 1 Sensor 2.
P0138 Oxygen Sensor Circuit High Voltage - Bank 1 Sensor 2.
P0139 Oxygen Sensor Circuit Slow Response - Bank 1 Sensor 2.
P0140 Oxygen Sensor Circuit No Activity detected - Bank 1 Sensor 2.
P0141 Oxygen Sensor Heater Circuit Malfunction - Bank 1 Sensor 2.
P0170 Fuel Trim Malfunction - Bank 1.
P0171 System too Lean - Bank 1.
P0172 System too Rich - Bank 1.
P0261 Injector Circuit Low - Cyl. 1.
P0262 Injector Circuit High - Cyl. 1.
P0264 Injector Circuit Low - Cyl. 2.
P0265 Injector Circuit High - Cyl. 2.
P0267 Injector Circuit Low - Cyl. 3.
P0268 Injector Circuit High - Cyl. 3.
P0270 Injector Circuit Low - Cyl. 4.
P0271 Injector Circuit High - Cyl. 4.
P0300 Multiple/Random Misfire detected.
P0301 Misfire detected - Cyls. 1-4.
P0302 Misfire detected - Cyls. 1-4.
P0303 Misfire detected - Cyls. 1-4.
P0304 Misfire detected - Cyls. 1-4.
P0325 Knock Sensor Circuit Malfunction
P0326 Knock Sensor 1 Circuit Range/Performance - Bank 1 or Single Sensor.
P0335 Crankshaft Position Sensor Malfunction - Circuit A.
P0336 Crankshaft Position Sensor Range/Performance - Circuit A.
P0340 Crankshaft Position Sensor Circuit Malfunction.
P0342 Crankshaft Position Sensor Circuit Low Input.
P0343 Crankshaft Position Sensor Circuit High Input.
P0400 EGR Flow Malfunction.
P0403 EGR Circuit Malfunction.
P0404 EGR Circuit Range/Performance Malfunction.
P0420 Catalyst System Efficiency below Threshold - Bank 1.
P0422 Main Catalyst Efficiency below Threshold - Bank 1.
P0440 Evaporative Control Malfunction.
P0441 Evaporative Control System - Improper Purge.
P0442 Evaporative Control System - Small Leak detected.
P0443 Evaporative Control System Purge Control Valve Circuit Malfunction.
P0446 Evaporative Vent Control Circuit Malfunction.
P0447 Evaporative Vent Control Circuit Open.
P0448 Evaporative Vent Control Circuit Short.
P0450 Evaporative System Pressure Sensor Circuit Malfunction.
P0452 Evaporative Control System Pressure Sensor Low Input.
P0453 Evaporative Control System Pressure Sensor High Input.
P0455 Evaporative Control System - Large Leak detected.
P0470 Exhaust Pressure Sensor Malfunction.
P0500 Vehicle Speed Sensor Malfunction.
P0501 Vehicle Speed Sensor Range/Performance.
P0505 Idle Air Control System Malfunction.
P0506 Idle Air Control System Malfunction - RPM Lower than expected.
P0507 Idle Air Control System Malfunction - RPM Higher than expected.
P0510 CTP Switch Malfunction.
P0561 System Voltage Unstable.
P0562 System Voltage Low.
P0563 System Voltage High.
P0601 Internal Control Module Memory Checksum Error.
P0604 Internal Control Module RAM Error.
P0703 Torque Converter/Brake Pedal Switch Malfunction - Circuit B.
P0705 Transaxle Range Sensor Circuit Malfunction (PRNDL Input).
P0706 A/T Range Sensor Circuit Range/ Performance.
P0710 Transaxle Fluid Temperature Sensor Circuit Malfunction.
P0711 A/T Fluid Temperature Sensor Circuit Range/Performance.
P0715 Input/Turbine Speed Sensor Circuit Malfunction.
P0722 Output Speed Sensor Circuit No Signal.
P0726 Engine Speed Input Circuit Range/ Performance.
P0727 Engine Speed Input Circuit - No Signal.
P0731 A/T Gear 1 Improper Ratio.
P0732 A/T Gear 2 Improper Ratio.
P0733 A/T Gear 3 Improper Ratio.
P0734 A/T Gear 4 Improper Ratio.
P0740 Torque Converter Clutch System Malfunction.
P0743 Torque Converter Clutch Circuit Electrical.
P0750 Shift Solenoid "A" Malfunction.
P0753 Shift Solenoid "A" Electrical.
P0755 Shift Solenoid "B" Malfunction.
P0758 Shift Solenoid "B" Electrical.
P0760 Shift Solenoid "C" Malfunction.
P1000 Readiness Function Code.
P1115 Engine Coolant Temperature Signal from ECM to TCM.
P1121 Throttle Position Sensor Signal Malfunction from ECM to TCM.
P1170 Front Heated Oxygen Sensor Stuck.
P1195 EGR Pressure Sensor (1.6L) or Boost Sensor (1.8L) Open or Short.
P1196 Ignition Switch "Start" Open or Short (1.6L).
P1250 Pressure Regulator Control Solenoid Valve Open or Short.
P1252 Pressure Regulator Control Solenoid Valve No. 2 Circuit Malfunction.
P1307 Chassis Acceleration Sensor Signal Malfunction.
P1308 Chassis Acceleration Sensor Signal Low.
P1309 Chassis Acceleration Sensor Signal High.
P1345 No SGC Signal (1.6L).
P1386 Knock Sensor Control Zero Test.
P1402 EGR Valve Position Sensor Open or Short.
P1449 Canister Drain Cut Valve Open or Short (1.8L).
P1450 Excessive Vacuum Leak.
P1455 Fuel Tank Sending Unit Open or Short (1.8L).
P1457 Purge Solenoid Valve Low System Malfunction.
P1458 A/C Compressor Control Signal Malfunction.
P1485 EGR Solenoid Valve Vacuum Open or Short.
P1486 EGR Solenoid Valve Vent Open or Short.
P1487 EGR Boost Sensor Solenoid Valve Open or Short.
P1496 EGR Stepper Motor Malfunction - Circuit 1 (1.8L).
P1497 EGR Stepper Motor Malfunction - Circuit 2 (1.8L).
P1498 EGR Stepper Motor Malfunction - Circuit 3 (1.8L).
P1499 EGR Stepper Motor Malfunction - Circuit 4 (1.8L).
P1500 No Vehicle Speed Signal to TCM.
P1505 Idle Air Control Valve Opening Coil Voltage Low.
P1506 Idle Air Control Valve Opening Coil Voltage High.
P1507 Idle Air Control Valve Closing Coil Voltage Low.
P1508 Idle Air Control Valve Closing Coil Voltage High.
P1523 VICS Solenoid Valve.
P1586 A/T-M/T Codification.
P1608 PCM Malfunction.
P1611 MIL Request Circuit Voltage Low.
P1614 MIL Request Circuit Voltage High.
P1624 MIL Request Signal from TCM to ECM.
P1631 Alternator "T" Open or No Power Output (1.8L).
P1632 Battery Voltage Detection Circuit for Alternator Regulator (1.8L).
P1633 Battery Overcharge.
P1634 Alternator "B" Open (1.8L).
P1693 MIL Circuit Malfunction.
P1743 Torque Converter Clutch Solenoid Valve Open or Short.
P1794 Battery or Circuit Failure.
P1795 4WD Switch Signal Malfunction.
P1797 P or N Range Signal or Clutch Pedal Position Switch Open or Short.

This is code 12 and it means "System Normal"
Here is the complete list of fault codes for your Buick
GM common codes for OBD1 (for vehicles made before 1995)
12 System normal
13 oxygen sensor circuit open
14 coolant sensor high resistance or shorted
15 coolant sensor circuit low or open
16 direct ignition system (DIS) fault in circuit
17 cam position sensor fault
18 crank or cam sensor error
19 crank sensor circuit fault
21 tps sensor out of range
22 tps sensor signal voltage low
23 intake air temp sensor out of range, low
24 vehicle speed (vss) sensor circuit fault
25 air temp sensor sensor out of range, high
26 quad-driver module (computer) circuit #1 fault
27 quad-driver module (computer) 2nd gear circuit
28 quad-driver module (computer) circuit #2 fault
29 quad driver module (computer) 4th gear circuit
31 cam position sensor fault
32 egr circuit fault
33 map sensor signal out of range, high
34 map sensor signal out of range, low
35 idle air control sensor circuit fault
36 ignition system circuit error
38 brake input circuit fault
39 clutch input circuit fault
41 cam sensor circuit fault, igntion control circuit fault
42 electronic spark timing (EST) circuit grounded
43 knock sensor
or electronic spark control circuit fault
44 oxygen sensor lean exhaust
45 oxygen sensor rich exhaust
46 pass-key II circuit or ps.pressure switch circuit fault
47 pcm-bcm data circuit
48 misfire diagnosis
51 calibration error, mem-cal, ecm or eeprom failure
52 engine oil temperature circuit, low temperature indicated
53 battery voltage error or egr or pass-key II circuit
54 egr system failure or fuel pump circuit low voltage
55 a/d converter error or pcm not grounded or lean fuel or frounded reference voltage
56 quad-driver module #2 circuit
57 boost control problem
58 vehicle anti-theft system fuel enable circuit
61 a/c system performance or degraded oxygen sensor signal
62 engine oil temperature high temperature indicated
63 oxygen sensor right side circuit open or map sensor out of range
64 oxygen sensor right side lean exhaust indicated
65 oxygen sensor right side rich exhaust indicated
66 a/c pressure sensor circuit low pressure
67 a/c pressure sensor circuit or a/c clutch circuit failure
68 a/c compressor relay circuit failure
69 a/c clutch circuit head pressure high
70 a/c refrigerant pressure circuit high
71 a/c evaporator temperature sensor circuit low
72 gear selector switch circuit
73 a/c evaporator temperature circuit high
75 digital egr #1 solenoid error
76 digital egr #2 solenoid error
77 digital egr #3 solenoid error
79 vehicle speed sensor (vss) circuit signal high
80 vehicle speed sensor (vss) circuit signal low
81 brake input circuit fault
82 ignition control (IC) 3X signal error
85 prom error
86 analog/digital ecm error
87 eeprom error
99 power management

CODE 12- NO DISTRIBUTOR REFERENCE PULSES ECM. CODE 13- OXYGEN CIRCUIT. CODE 14- COOLANT SENSOR HIGH TEMP CODE 15- COOLANT SENSOR LOW TEMP. CODE 21 - THROTTLE POSITION SENSOR VOLTAGE HIGH.CODE 22 - THROTTLE POSITION SENSOR VOLTAGE LOW.CODE - 23 MIXTURE CONTROL SOLENOID.FOR CARBURETOR ENGINE. CODE 24 -VECHICLE SPEED SENSOR. CODE 32 - BARO CIRCUIT LOW.CODE 32 - FUEL INJECTED EGR VALVE VACUUM SWITCH SHORTED TO GROUND.OR EGR VALVE SOLENOID CIRCUIT OPEN. CODE 33 - MAP SENSOR.CODE 34 - VACUUM SENSOR OR MAP SENSOR.CODE 35 - IDLE SPEED CONTROL. CODE 41 - EST CIRCUIT. CODE 42 - ELECTRONIC SPARK TIMING.CODE 43 - ELECTRONIC SPARK CONTROL UNIT. CODE 44 - LEAN EXHAUST.CODE 45 - RICH EXHAUST. CODE 51 - PROM OR MEM CAL.CODE 52 - CALPAK. CODE 53 -EGR VALVE CARBURETED ENGINE THE EGR VALVE VACUUM SENSOR HAS RECEIVED IMPROPER EGR VACUUM. CODE 54 - M C SOLENOID CARBURETED ENGINE MIXTURE CONTROL SOLENOID SHORTED OR FAULTY ECM.CODE 54- FUEL INJECTED ENGINE FUEL PUMP VOLTAGE IS LOW.CODE 55 - ECM MAKE SURE PCM GROUND CONNECTIONS ARE TIGHT.IF OKAY.REPLACE THE ECM.

2 airflow sensor out of operating range 3 coolant temp sensor out of operating range 4 oxy sensor indicates full rich 5 throttle potentiometer/airflow sensor... (low throttle pot signal with high airflow sensor signal) 6 throttle pot/airflow sensor...... (high throttle pot signal with low airflow sensor signal) 7 throttle pot...idle fuel adjustment failure(idle speed??) 8 intake air temp sensor...open or shorted circuit to sensor 11 Throttle pot at idle: Throttle pot idle trim out of normal range 12 Airflow meter: MAF signal out of range 14 Coolant thermistor: Resistance out of range or static during engine warm up 16 Air thermistor: Resistance out of range 17 Throttle pot: Out of range 18 Throttle pot/Airflow: Low throttle pot signal at high airflow 19 Throttle pot/Airflow: High throttle pot signal at low airflow 22 Fuel pump drive: ECU output to fuel pump relay 23 Fuel supply: Engine running too rich 24 Ignition Drive: ECU output to ignition Amp 26 Air leak: Engine running too lean 29 ECU self check 33 Injector Drive: ECU output to injectors 34 Injector: Looks for Injector dribble 37 EGR Drive: ECU output to EGR switching valve 39 EGR check sensor: EGR not working (normally pipe blocked) 44 Lambda (O2) sensor: Poor mixture control rich or weak (or misfire) 46 Idle speed Control valve: ECU output to Coil AB 47 Idle speed Control valve: ECU output to Coil CD 48 Idle Speed Control Valve: Stepper motor grossly out of position 66 Air pump: ECU output to air pump relay 68 Road speed sensor: Seen speed < 5km/h at high engine airflow 69 Drive/Neutral switch: Seen cranking in "D" or high airflow in "N" 89 Purge Valve drive: ECU output to purge valve
this is all I could find

CODE 14
Trouble Code 14 indicates that the Coolant Temperature Sensor (CTS) is reporting abnormally high readings. CTS is used to control fuel mixture, timing, idle speed, TCC and EGR operations among others. The thermistor used has a low resistance when hot, rising as the coolant cools. This error then, indicates a very low resistance in the CTS circuit.
CODE 15
Trouble Code 15 indicates that the Coolant Temperature Sensor (CTS) is reporting abnormally low readings. CTS is used to control fuel mixture, timing, idle speed, TCC and EGR operation, among others. The thermistor used has a high resistance when cold, lowering as the coolant warms. This error then, indicates a very high resistance in the CTS circuit.
CODE 33
Trouble Code 33 indicates that the Mass Air Flow (MAF) sensor is reporting more air is entering the engine than makes sense based on RPM and TPS. The MAF sensor produces a frequency output; around 30 Hz at idle to 150 Hz under acceleration. The frequency varies proportionally to airflow. The ECM monitors the frequency and thus determines airflow into the engine. Typical idle MAF is 5 to 7 grams per second.