Hey all, I bought a 1989 IROC about a week ago. It has a funny hesitation sometimes, when I step on the gas. It doesn't do it all the time. Seems like it only does it when I'm accelerating, almost like its missing. The check engine light is also on, which leads me to belive they are related. I replaced the fuel filter, air filters, distributor cap and rotor. I wanted to replace the plugs and wires as well, but the plugs are impossible to get to. The ones i can get to won't come out. Needless to say the plugs and wires did not get replaced. Can anyone tell me what the problem might be? Im hoping it's not the fuel pump going out. I know the car is 17 yrs old, but i'm hoping to solve my problem, before it nickle and dimes me to death. Any suggestions would be great. thanks

pull the codes, and go from there.

THE CONNECTOR


-----------------------
| 1 2 3 -4 -5 -6 |
| 7 8 9 10 11 12 |
-----------------------


DISPLAYING THE TROUBLE CODES
Run a wire/hairpin from Pin 6 to Pin 12 with the ignition off (although on later cars it should be from Pin 5 to Pin 6), then turning the ignition to the on position without starting the engine will flash the "Service Engine Soon" light in the following sequence: flash, pause, flash-flash, long pause flash, pause, flash-flash, long pause flash, pause, flash-flash, long pause Following this "12" code repeating three times will come any trouble codes stored, flashing each of them three times. If you do not see the "12" flash three times, your diagnostic circuit is defective.
Some vehicles will display stored trouble codes, then "12" again, followed by energizing "most system controlled relays." The fuel pump relay will not energize. The idle air control valve will fully extend to enable checking minimum idle speed.

CLEARING THE TROUBLE CODES
Turn the keyswitch to the off position. To clear any trouble codes, disconnect the power feed for 30 seconds. If this is done at the battery, and your car stereo is equipped and programmed with a four digit pin code, you may have to re-enter that as well to use your stereo again. A better place to remove power is at the fuse.

TROUBLE CODES


12. No reference pulses to Electronic Control Module (ECM).
13. Oxygen sensor signal stays lean during warm engine cruise
14. High temperature indicated at engine coolant temp. sensor
15. Low temperature indicated at engine coolant temp. sensor
16. High battery voltage OR
Direct inition system open or shorted to ground
17. RPM signal problem
18-20. N/A
21. High voltage at throttle positon sensor
22. Low voltage at throttle positon sensor OR
Fuel cutoff relay circuit open or shorted to ground
23. Low temperature at manifold air temperature sensor OR
Throttle position sensor error
24. Circuit fault in vehicle speed sensor
25. High temperature at manifold air temperature sensor OR
Vacuum switching valve circuit open or shorted to ground OR
High voltage at ATS sensor
26. Fault in quad driver module
27. Fault in 2nd gear switch
28. Fault in 3rd gear switch
29. Fault in 4th gear switch
30. N/A
31. Low voltage at manifold absolute pressure sensor OR
Fuel injector OR
Park or neutral switch OR
CAM diagnostic OR
Governor malfunction OR
Wastegate overboost OR
Wastegate eletrical signal open or shorted to ground
32. Fault in barometric pressure sensor circuit OR
Fault in exhaust gas recirculation valve diagnostic switch OR
Fault in electronic vacuum regulator valve
33. High voltage (low vacuum) at mass air flow sensor (or MAP sensor)
34. Low voltage (high vacuum) at mass air flow sensor (or MAP sensor)
35. Idle speed can not be set to desired RPM
36. Burn off at mass air flow sensor OR
Problem in transmission shift OR
Fault in direct ignition system OR
Missing pulses in electronic spark timing signal
37. N/A
38. Fault in torque converter clutch brake switch
39. Fault in torque converter clutch circuit
40. N/A
41. Fault at cam sensor OR
Cylinder select error OR
Tach input error
42. Fault at electronic spark timing circuit OR
Fault at direct ignition system OR
Fault at fuel cutoff relay circuit
43. Low voltage at electronic spark timing circuit
44. Oxygen sensor lean
45. Oxygen sensor rich
46. Fault at vehicle anti-theft sytem OR
Fault at power steering switch
47. Problem at Electronic Control Module (ECM)
48. Misfire
49. Vacuum leak
50. N/A
51. PROM error
52. Problem at Electronic Control Module (ECM) -
Missing fuel calpac missing OR
Analog to digital converter error OR
Fault at quad driver module OR
Low voltage at oil temperature sensor
53. High voltage at battery OR
High voltage at exhaust gas recirculation valve OR
Voltage reference error OR
Problem at vehicle anti-theft system
54. Low voltage at fuel pump OR
Low voltage at Fuel pump relay OR
Output failure at quad driver module
55. Problem at Electronic Control Module (ECM) -
ECM failure OR
Serial bus error OR
Fuel lean malfunction
56. Low coolant or corrosivity OR
Fault in port throttle system vacuum sensor
57. N/A
58. Problem at vehicle anti-theft system
59-60. N/A
61. Oxygen sensor degraded OR
Port throttle system error OR
Cruise control problems
62. Gear switch input diagnostics OR
High voltage at oil temperature sensor OR
Fault in cruise control- vacuum solenoid circuit
63. High voltage at manifold absolute pressure sensor OR
Fault in exhaust gas recirculation valve OR
Fault at right oxygen sensor
64. Low voltage at manifold absolute pressure sensor OR
Fault in exhaust gas recirculation valve OR
Right oxygen sensor lean
65. Failure at exhaust gas recirculation valve OR
Faulure at injector peak/hold diagnostic OR
Right oxygen sensor rich OR
Fault at cruise control position sensor
66. Internal reset of Electronic Control Module (ECM)
67. Fault at cruise control switch
68. Fault at cruise control switch
69. Fault at air conditioner pressure switch
70-87. N/A
88. Internal reset of Electronic Control Module (ECM)

In all honesty, it could be the plugs. If the plugs have been installed long enough to become stuck, they are probably worn out as well.

IM NOT SURE HOW THE TROUBLE CODE WILL BE DISPLAYED. IS THE CODE THE NUMBER OF FLASHES, OR WILL IT ACTUALLY DISPLAY A NUMBER? EXACTLY WHERE IS THE TROUBLE CODE DISPLAYED?

The code will be the number of flashes. IT will flash a number of times corresponding to the first digit, pause, then flash the second digit.

FORGIVE ME....I TOTALLY MISUNDERSTOOD YOUR EXPLAINATION. I WILL TRY TO GET THE CODES LATER ON TODAY. IM SURE THIS WILL NOT BE THE LAST TIME YOU HEAR FROM ME.

THANKS AGAIN