Is my pcm fried??
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Joined: Nov 2006
Posts: 79
Is my pcm fried??
K well I have a 1994 z28 lt1 6spd and here is my problem when I accelerate rapidly and its gets between 4500+ rpm its starts cutting out almost like its being starved for fuel and backfires once in a while. These are the codes that it set #26 Quad driver module 1 fault,#22 Throttle position sensor too low #43 esc module or sensor circuit problem and #84 downshift feedback fault. My uncle who is a mechanic said my pcm could be junk? but idk i just want to get a second opinion before i spend $175 on a new one.
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Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
You just need to get on with fixing some stuff. PCMs rarely go bad. Sounds like you have some wiring/electrical issues.
26 Evaporative Emission (EVAP) canister purge solenoid valve circuit
22 Throttle Position (TP) sensor circuit (signal voltage low)
43 Knock Sensor (KS) circuit
84 Skip shift solenoid circuit (manual transmission)
26 Evaporative Emission (EVAP) canister purge solenoid valve circuit
22 Throttle Position (TP) sensor circuit (signal voltage low)
43 Knock Sensor (KS) circuit
84 Skip shift solenoid circuit (manual transmission)
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Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Next time, use Shoebox's list of LT1 codes. The last year for the "Quad Driver Modules" was 1993. That is not the correct description for a 94.
http://shbox.com/1/Dtcs.htm
PCM's seldom fail. For example, does the skip shift solenoid prevent you from shifting 1->2 at part throttle? If not, its likely someone pulled the harness connector off the solenoid on the side of the tranny, to defeat the system. Open circuit sets the DTC 84 code, and does not hurt anything. The code can be eliminated with a 2Kohm resistor.
Knock sensor code is easy to track down. Pull the harness connector off the sensor, and measure the voltage between the single wire in the harness, and the block. Should be 5V. Then with the connector still off, measure the resistance of the knock sensor, from the single pin on the sensor to engine block. Should be in the range of 3,500-4,500 ohms. That code is causing you a significant performance loss, since the PCM will retard the ignition timing almost constantly.
Evap purge solenoid is easy to check as well, and you can put the volt meter across the TPS sensor and check the voltage for dropouts as you slowly rotate the throttle, and wiggle the connector. If you want details on these two, let us know.
http://shbox.com/1/Dtcs.htm
PCM's seldom fail. For example, does the skip shift solenoid prevent you from shifting 1->2 at part throttle? If not, its likely someone pulled the harness connector off the solenoid on the side of the tranny, to defeat the system. Open circuit sets the DTC 84 code, and does not hurt anything. The code can be eliminated with a 2Kohm resistor.
Knock sensor code is easy to track down. Pull the harness connector off the sensor, and measure the voltage between the single wire in the harness, and the block. Should be 5V. Then with the connector still off, measure the resistance of the knock sensor, from the single pin on the sensor to engine block. Should be in the range of 3,500-4,500 ohms. That code is causing you a significant performance loss, since the PCM will retard the ignition timing almost constantly.
Evap purge solenoid is easy to check as well, and you can put the volt meter across the TPS sensor and check the voltage for dropouts as you slowly rotate the throttle, and wiggle the connector. If you want details on these two, let us know.
Thread Starter
Registered User
Joined: Nov 2006
Posts: 79
Thread Starter
Registered User
Joined: Nov 2006
Posts: 79
Next time, use Shoebox's list of LT1 codes. The last year for the "Quad Driver Modules" was 1993. That is not the correct description for a 94.
http://shbox.com/1/Dtcs.htm
PCM's seldom fail. For example, does the skip shift solenoid prevent you from shifting 1->2 at part throttle? If not, its likely someone pulled the harness connector off the solenoid on the side of the tranny, to defeat the system. Open circuit sets the DTC 84 code, and does not hurt anything. The code can be eliminated with a 2Kohm resistor.
Knock sensor code is easy to track down. Pull the harness connector off the sensor, and measure the voltage between the single wire in the harness, and the block. Should be 5V. Then with the connector still off, measure the resistance of the knock sensor, from the single pin on the sensor to engine block. Should be in the range of 3,500-4,500 ohms. That code is causing you a significant performance loss, since the PCM will retard the ignition timing almost constantly.
Evap purge solenoid is easy to check as well, and you can put the volt meter across the TPS sensor and check the voltage for dropouts as you slowly rotate the throttle, and wiggle the connector. If you want details on these two, let us know.
http://shbox.com/1/Dtcs.htm
PCM's seldom fail. For example, does the skip shift solenoid prevent you from shifting 1->2 at part throttle? If not, its likely someone pulled the harness connector off the solenoid on the side of the tranny, to defeat the system. Open circuit sets the DTC 84 code, and does not hurt anything. The code can be eliminated with a 2Kohm resistor.
Knock sensor code is easy to track down. Pull the harness connector off the sensor, and measure the voltage between the single wire in the harness, and the block. Should be 5V. Then with the connector still off, measure the resistance of the knock sensor, from the single pin on the sensor to engine block. Should be in the range of 3,500-4,500 ohms. That code is causing you a significant performance loss, since the PCM will retard the ignition timing almost constantly.
Evap purge solenoid is easy to check as well, and you can put the volt meter across the TPS sensor and check the voltage for dropouts as you slowly rotate the throttle, and wiggle the connector. If you want details on these two, let us know.
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