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I would suggest that you take your car to O'rielly's or one of the larger auto parts chain stores and have them connect the diagnostic reader to your car. It sounds to me as though you are experiencing something to do with the cars computer and the way it is reading it's sensors. They will do this for free and then tell you what the error codes mean, if any. If you do receive error codes, chances are that is your problem and you will then be aware of what it is and what it will cost to clear it up and not have some mechanic charging you for his time doing exploratory diagnostics and charging you an arm and a leg just to find out whats wrong.
1991 is pre-OBD2. code readers will not work.
sorry.
however, all is not lost. Many cars have an alternate way of reading codes from the computer.
Toyota has a block under the hood and you short couple wires together and count engine light flashes
Chrysler you can turn the ignition key on and off a few times and count engine light flashes
in your case for GMs from 1982 to 1995
1: find the 12 pin connector under the dash and short the upper two rightmost terminals.
with the ignition "ON" and engine not running. The system will enter the diagnostic mode. In this mode, the computer will display a Code 12, three consecutive times, by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" or light. A Code 12 consists of one flash, a short pause, then two flashes in rapid succession.
2:. After Code 12 is displayed, any stored trouble codes will be displayed by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" light. All codes are displayed 3 times each then a code 12 will repeat. In the diagnostic mode, the computer will also energize all computer controlled relays and solenoids.
Tech -- GM 2 Digit codes for 82 and up (non OBD-II)
code - code definition
12- diagnostic mode
13- 02 sensor or circuit
14- coolant sensor or circuit/ high temp indicated
15- coolant sensor or circuit/ low temp indicated
16- system voltage out of range
19- crankshaft position sensor or circuit
21- throttle position sensor or circuit- voltage high
22- throttle position sensor or circuit- voltage low
23- mixture control (m/c) solenoid or circuit (carbureted models)
23- manifold air temperature (mat) sensor or circuit (1990 and earlier models)
23- intake air temperature (iat) sensor circuit (fuel-injected models)
24- vehicle speed sensor (vss) or circuit
25- manifold air temperature (mat) sensor or circuit - high temperature indicated (1990 and earlier models)
25- intake air temperature (iat) sensor or circuit - high temperature indicated (1991 and later models)
26- quad driver module circuit
27- quad driver module circuit
28- quad driver module circuit
29- quad driver module circuit
31- park/neutral position (pnp) switch circuit
32- baro sensor or circuit (carbureted models)
32- egr circuit (fuel-injected models)
33- manifold absolute pressure (map sensor signal voltage high
33- mass air flow (maf) sensor or circuit - excessive airflow indicated
34- manifold absolute pressure (map) sensor signal voltage low 34- mass air flow (maf) sensor signal - low airflow indicated
35- idle speed control (isc) switch or circuit (shorted) (carbureted models)
35- idle air control (iac) valve/ circuit
38- brake switch circuit
39- torque converter clutch (tcc) circuit
41- no distributor signals to ecm, or faulty ignition module ( carbed models)
41- cylinders select error- mem-cal or ecm problem ( fuel-injected models
41- cam sensor circuit (3.8 engine)
42- bypass or electronic spark timing (est) circuit
43- low voltage at ecm terminal l (carbureted models)
43- knock sensor circuit
44- oxygen sensor or circuit - lean exhaust detected
45- oxygen sensor or circuit - rich exhaust detected
46- power steering pressure switch circuit
48- misfire diagnosis
51- prom, mem-cal or ecm problem
52- calpak or ecm problem
53- egr fault (carbureted models only)
53- system over-voltage (ecm over 17.7 volts)
54- mixture control (m/c) solenoid or circuit (carbureted models)
54- fuel pump circuit (1986 and later models)
55- oxygen sensor circuit or ecm
55- fuel lean monitor (2.2l engine)
61- oxygen sensor signal faulty (possible contaminated sensor)
62- transaxle gear switch signal circuits
63- manifold absolute pressure (map) sensor voltage high (low vacuum detected)
64- manifold absolute pressure (map) sensor voltage low (high vacuum detected)
66- pressure sensor or circuit air conditioning
Sounds fuel related. but, first, when was your last tune-up(plugs, fuel filter, pcv valve, air filter, check all fluid levels)? If everything has been checked, the next thing is get your fuel pressure checked with a fuel pressure gauge. Also have your diagnostic codes, if any, read by a parts store for free. A code will direct you to an engine or emissions-related problem.
IDLE SPEED TO LOW.MANUAL TRANSMISSION IDLE SPEED IS 750 RPM AND AUTOMATIC TRANSMISSION IDLE SPEED IS 850 RPM.IF IDLE SPEED IS CORRECT YOUR PROBLEM COULD BE STOPPED UP FUEL FILTER OR FAULTY SPARK PLUGS AND WIRES.YOUR IGNITION TIMING IS OFF.YOU COULD HAVE INTAKE VACUUM LEAK AT INTAKE MANIFOLD OR EGR VALVE GASKET LEAKING OR BAD FUEL INJECTOR IF YOU HAVE FUEL INJECTION.FAULTY MECHANICAL FUEL PUMP IF CARBURETOR.ALSO CARBURETOR FLOAT BOWL TOO LOW.
Hi. The best action in this situation will be to run the codes. This can be achieved by taking this vehicle to a local auto-zone, or dealership. I recommendauto-zone, they will run a diagnostic scan for free. Once the Vehicles CPU is scanned, it will isolate the actual issue that is causing this hesitation, and low idle. Running codes will prevent you from wasting money on parts that you don't need to purchase. The scan will give you an accurate print out that will inform you of the failing component.
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