IAC minimum air adjustment tech article ????
Thread Starter
Supreme Member
Joined: Jul 1999
Posts: 2,149
Likes: 4
From: Mims, Florida
Car: '87 IROCZ
Engine: 395 ZZ4
Transmission: ProBuilt 700R4
Axle/Gears: 9 bolt 3.70s
IAC minimum air adjustment tech article ????
I just noticed that the tech article on the subject does not spell out when do you remove the paper clip from the ALDL connector.
I would think that after you have remove the connector from the IAC, then turn the key to off and remove the paper clip. Then start engine and set minimum idle speed.
What do you guys think?
I would think that after you have remove the connector from the IAC, then turn the key to off and remove the paper clip. Then start engine and set minimum idle speed.
What do you guys think?
Senior Member
Joined: Jul 2002
Posts: 631
Likes: 2
From: Saskatchewan
Car: 1992 GTA
Engine: LS1
Transmission: T56
Axle/Gears: 4.10
Originally posted by Vader
Yes, the engien should odle at the specified RPM for minimum air position adjustment (in DRIVE with an automatic).
I'm not sure what article you may have read, but try this procedure:
Throttle Minimum Air Position
Tools needed:
1. Torx driver # T-20
2. Paper Clip
3. Small Punch
4. Tachometer
GENERAL NOTE: The engine should be at normal operating temperature before performing any adjustments. Never rely on the dash mounted instruments for diagnostics and adjustments. The oil pressure and temperature gauges and the voltmeter and tachometer just aren't calibrated accurately enough for diagnosis, but are a relative indication for monitoring the vehicle while driving.
For this adjustment, the transmission will be in DRIVE while you're under the hood. You will need to securely set the parking brake and block the drive wheels. It would also be a good idea to have an assistant hold the service brake while you perform the adjustments.
In order to successfully complete the adjustment, the IAC air passages and pintle need to be clean. The throttle plates and bores need to be clean as well. If this is not the case, you'll need to remove the air cleaner from TBI engines or the intake air bellows from TPI engines to gain access to the area to be cleaned. A spray-type carburetor cleaner works well for this. Cleaning the IAC passages on a TPI/MAF engine will set a DTC, but we'll be clearing that later. With the engine idling, direct the spray cleaner in to the IAC air passages and around the throttle plates. Shut off the engine and continue cleaning the throttle plates by opening the throttle manually. Once everything is satisfactorily cleaned, replace the air bellows on TPI engines. Many times, this alone can solve IAC/idle speed problems.
If this doesn't solve the problem, you may need to remove and clean the IAC stepper motor. If the IAC appears to be clean and functioning properly, continue with the adjustment procedure.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Idle Air Control Cleaning
You can remove the IAC and service it. Remove the electrical connector from the IAC. Unscrew the IAC unit from the throttle body.
You can gently rock the pintle back and forth and allow the spring to extend it until it comes apart in your hands. Clean everything with lint-free cloths and a mild solvent. Harsh solvents can affect the insulation of the stepper motor coils. It's generally the dirt and buildup on this worm shaft that causes sluggish IAC operation.
When the worm gear on the pintle shaft is clean and dry, apply one drop of clean light oil to the shaft and work the pintle back into the rack gears of the motor by the same rocking motion. It takes a while to get the pintle back into the worm gears, but you'll get it. It is important to get the pintle fully retracted into the housing so that the pintle is not forced against the gears when reinstalling the IAC unit in the throttle body.
While the IAC is out, clean the air passages in the throttle body. The orifice in the TB where the IAC resides is the seat that the IAC valve closes against, and it can accumulate a lot of carbon, dirt, and debris. The easy way to do this is with carburetor cleaner and a small stiff brush.
When everything is clean and dry, replace the gasket if it is damaged, apply a little anti-seize to the threads, and torque the IAC to the proper specs. (13 ft/lb for '85-'89 , 30 in/lb for 1990-on.) Proceed with setting the TPS and minimum air position.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Locate the ALDL connector under your dash panel, in the driver's footwell area. Remove the plastic trim cover (if it is still there).
Cut and form a paper clip into a "U" shape. Insert the clip ends into the ALDL in the 'A' and 'B' sockets.
Turn on the ignition, but don't start the engine. This will force the ECM into its diagnostic mode. Wait 30 seconds to allow the IAC pintle to fully extend. Under the hood, remove the electrical connector from the IAC, then turn off the ignition and remove the paper clip jumper from the ALDL. With the IAC pintle fully extended (closed) all idle air will be controlled by the position of the throttle plates. Some manuals indicate that the EST bypass connector should be disconnected for this procedure, while some make no mention of it. While timing is a factor in idle speed, the EST should only operate as a function of engine RPM, temperature, and detonation sensor inputs. To remove all doubt, disconnect the EST bypass connector is your car is so equipped. Some TBI and V-6 engines do not have this bypass connector, and therefore must be set with no regard to the EST system. The EST can be bypassed on some cars by grounding the diagnostic terminal at the ALDL and continuing with the procedure, but the fuel mixture will be skewed to the rich side, affecting idle speed as well. In any event, the minimum air position idle speed range is wide enough to allow for some variations. As always, it is best to consult your service manual for the exact procedure for your system.
Locate the Torx screw on the left side of the throttle body. It may be equipped with a protective metal cap from the factory. This was intended to discourage adjustment. If the cap is present, use a small punch to knock it out. Once the screw is accessible, start the engine and place the transmission in DRIVE. Adjust the throttle stop to obtain 400 RPM with the transmission in "DRIVE" on an automatic transmission car, 450 in neutral on a manual transmission car, rotating the Torx screw clockwise to raise speed and counter-clockwise to lower speed. Once the idle RPM is set, place the transmission in PARK and turn off the engine.
Re-connect the electrical connector onto the IAC. Start engine. Idle speed should be governed by the ECM at approximately 600-650 rpm in "DRIVE" (for unmodified cars). Idle speed in NEUTRAL or PARK is less significant, and will be higher.
Throttle Position Sensor (TPS)
Tools needed:
1. Digital Volt-Ohm-Meter (VOM)
2. Breakout jumper wires or probes (make your own)
3. AutoXray, Diacom, or similar scanner will replace the VOM and jumper wires.
Turn on ignition, but don't start the engine.
With a diagnostic scanner: plug in the scanner and read the TPS voltage. It should be 0.54Volts +/- 0.07 VDC.
Connect the VOM to the TPS electrical connector terminals ‘A' and ‘B'.
With a breakout jumper: Disconnect the electrical connector from the TPS. Install the breakout in-line, between the TPS and wiring harness connector. Connect the meter probes to terminals 'A' and 'B' on the connector. (‘B' is the positive connection, ‘A' the signal ground, or negative.)
With probes: If you have very slender probes on your VOM, you can back-probe the TPS connector while it is attached to the TPS. If you have made probes of large dressmakers pins or a similar item, you can back-probe the connector as well. Connect the meter probes to terminals 'A' and 'B' on the connector.
Turn on the ignition to read the TPS output voltage at the idle position. The reading should be 0.54VDC +/- 0.07VDC. The ideal is the center of the range, 0.54VDC for a stock engine. To adjust the output voltage, loosen the two Torx screws holding the TPS to the throttle body, and slightly rotate the TPS up or down, reading the voltage until it comes into specification. Tighten screws. Using the throttle lever, rotate the throttle to WOT (wide open throttle). The TPS voltage should be over 4.0 volts. Close the throttle again, and then slowly open it to WOT, observing the voltage reading. It should increase progressively and in a linear fashion. If it sticks or jumps or falls off at all while doing this check, the TPS sensor may be failing and could be a cause of stumbling and driveability problems.
After achieving the desired setting, turn off the ignition switch. Remove all jumpers or the scanner and reconnect the TPS connector as required.
Reinitializing the ECM
If you set a DTC during the procedure, the SES light should be illuminated on the dash. This ECM retains DTC data for the previous 50 engine starts, so the codes will eventually be cleared. If you want more immediate results, after shutting down the engine disconnect the negative battery terminal for five minutes. This will clear the ECM of all diagnostic trouble codes. Clearing the ECM also clears any data learned about your engine, and clears the radio presets. If you have a Delco-Loc or Theft Loc II radio, make sure you follow the procedure to unlock the radio protection before disconnecting the battery. This five minutes is also just about long enough to clean both battery cables. Reconnect the battery. When you first start the engine after clearing the ECM, the engine will operate with base parameters programmed into the ECM PROM. These parameters may not be optimum for your engine, but the ECM will enter a Block Learn Mode soon after the engine is warm and enters Closed Loop Mode. The ECM will write new data tables specific to your engine and will eventually rely on those tables instead of the base tables of the factory program. You can expedite this process by driving the car for 20 minutes under varying conditions to allow the ECM to initialize. Or you can wait and drive the car normally at your convenience. The BLM tables are constantly being updated as sensor input ranges change, but the greatest change will occur within the first twenty minutes of Closed Loop operation.
Yes, the engien should odle at the specified RPM for minimum air position adjustment (in DRIVE with an automatic).
I'm not sure what article you may have read, but try this procedure:
Throttle Minimum Air Position
Tools needed:
1. Torx driver # T-20
2. Paper Clip
3. Small Punch
4. Tachometer
GENERAL NOTE: The engine should be at normal operating temperature before performing any adjustments. Never rely on the dash mounted instruments for diagnostics and adjustments. The oil pressure and temperature gauges and the voltmeter and tachometer just aren't calibrated accurately enough for diagnosis, but are a relative indication for monitoring the vehicle while driving.
For this adjustment, the transmission will be in DRIVE while you're under the hood. You will need to securely set the parking brake and block the drive wheels. It would also be a good idea to have an assistant hold the service brake while you perform the adjustments.
In order to successfully complete the adjustment, the IAC air passages and pintle need to be clean. The throttle plates and bores need to be clean as well. If this is not the case, you'll need to remove the air cleaner from TBI engines or the intake air bellows from TPI engines to gain access to the area to be cleaned. A spray-type carburetor cleaner works well for this. Cleaning the IAC passages on a TPI/MAF engine will set a DTC, but we'll be clearing that later. With the engine idling, direct the spray cleaner in to the IAC air passages and around the throttle plates. Shut off the engine and continue cleaning the throttle plates by opening the throttle manually. Once everything is satisfactorily cleaned, replace the air bellows on TPI engines. Many times, this alone can solve IAC/idle speed problems.
If this doesn't solve the problem, you may need to remove and clean the IAC stepper motor. If the IAC appears to be clean and functioning properly, continue with the adjustment procedure.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Idle Air Control Cleaning
You can remove the IAC and service it. Remove the electrical connector from the IAC. Unscrew the IAC unit from the throttle body.
You can gently rock the pintle back and forth and allow the spring to extend it until it comes apart in your hands. Clean everything with lint-free cloths and a mild solvent. Harsh solvents can affect the insulation of the stepper motor coils. It's generally the dirt and buildup on this worm shaft that causes sluggish IAC operation.
When the worm gear on the pintle shaft is clean and dry, apply one drop of clean light oil to the shaft and work the pintle back into the rack gears of the motor by the same rocking motion. It takes a while to get the pintle back into the worm gears, but you'll get it. It is important to get the pintle fully retracted into the housing so that the pintle is not forced against the gears when reinstalling the IAC unit in the throttle body.
While the IAC is out, clean the air passages in the throttle body. The orifice in the TB where the IAC resides is the seat that the IAC valve closes against, and it can accumulate a lot of carbon, dirt, and debris. The easy way to do this is with carburetor cleaner and a small stiff brush.
When everything is clean and dry, replace the gasket if it is damaged, apply a little anti-seize to the threads, and torque the IAC to the proper specs. (13 ft/lb for '85-'89 , 30 in/lb for 1990-on.) Proceed with setting the TPS and minimum air position.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Locate the ALDL connector under your dash panel, in the driver's footwell area. Remove the plastic trim cover (if it is still there).
Cut and form a paper clip into a "U" shape. Insert the clip ends into the ALDL in the 'A' and 'B' sockets.
Turn on the ignition, but don't start the engine. This will force the ECM into its diagnostic mode. Wait 30 seconds to allow the IAC pintle to fully extend. Under the hood, remove the electrical connector from the IAC, then turn off the ignition and remove the paper clip jumper from the ALDL. With the IAC pintle fully extended (closed) all idle air will be controlled by the position of the throttle plates. Some manuals indicate that the EST bypass connector should be disconnected for this procedure, while some make no mention of it. While timing is a factor in idle speed, the EST should only operate as a function of engine RPM, temperature, and detonation sensor inputs. To remove all doubt, disconnect the EST bypass connector is your car is so equipped. Some TBI and V-6 engines do not have this bypass connector, and therefore must be set with no regard to the EST system. The EST can be bypassed on some cars by grounding the diagnostic terminal at the ALDL and continuing with the procedure, but the fuel mixture will be skewed to the rich side, affecting idle speed as well. In any event, the minimum air position idle speed range is wide enough to allow for some variations. As always, it is best to consult your service manual for the exact procedure for your system.
Locate the Torx screw on the left side of the throttle body. It may be equipped with a protective metal cap from the factory. This was intended to discourage adjustment. If the cap is present, use a small punch to knock it out. Once the screw is accessible, start the engine and place the transmission in DRIVE. Adjust the throttle stop to obtain 400 RPM with the transmission in "DRIVE" on an automatic transmission car, 450 in neutral on a manual transmission car, rotating the Torx screw clockwise to raise speed and counter-clockwise to lower speed. Once the idle RPM is set, place the transmission in PARK and turn off the engine.
Re-connect the electrical connector onto the IAC. Start engine. Idle speed should be governed by the ECM at approximately 600-650 rpm in "DRIVE" (for unmodified cars). Idle speed in NEUTRAL or PARK is less significant, and will be higher.
Throttle Position Sensor (TPS)
Tools needed:
1. Digital Volt-Ohm-Meter (VOM)
2. Breakout jumper wires or probes (make your own)
3. AutoXray, Diacom, or similar scanner will replace the VOM and jumper wires.
Turn on ignition, but don't start the engine.
With a diagnostic scanner: plug in the scanner and read the TPS voltage. It should be 0.54Volts +/- 0.07 VDC.
Connect the VOM to the TPS electrical connector terminals ‘A' and ‘B'.
With a breakout jumper: Disconnect the electrical connector from the TPS. Install the breakout in-line, between the TPS and wiring harness connector. Connect the meter probes to terminals 'A' and 'B' on the connector. (‘B' is the positive connection, ‘A' the signal ground, or negative.)
With probes: If you have very slender probes on your VOM, you can back-probe the TPS connector while it is attached to the TPS. If you have made probes of large dressmakers pins or a similar item, you can back-probe the connector as well. Connect the meter probes to terminals 'A' and 'B' on the connector.
Turn on the ignition to read the TPS output voltage at the idle position. The reading should be 0.54VDC +/- 0.07VDC. The ideal is the center of the range, 0.54VDC for a stock engine. To adjust the output voltage, loosen the two Torx screws holding the TPS to the throttle body, and slightly rotate the TPS up or down, reading the voltage until it comes into specification. Tighten screws. Using the throttle lever, rotate the throttle to WOT (wide open throttle). The TPS voltage should be over 4.0 volts. Close the throttle again, and then slowly open it to WOT, observing the voltage reading. It should increase progressively and in a linear fashion. If it sticks or jumps or falls off at all while doing this check, the TPS sensor may be failing and could be a cause of stumbling and driveability problems.
After achieving the desired setting, turn off the ignition switch. Remove all jumpers or the scanner and reconnect the TPS connector as required.
Reinitializing the ECM
If you set a DTC during the procedure, the SES light should be illuminated on the dash. This ECM retains DTC data for the previous 50 engine starts, so the codes will eventually be cleared. If you want more immediate results, after shutting down the engine disconnect the negative battery terminal for five minutes. This will clear the ECM of all diagnostic trouble codes. Clearing the ECM also clears any data learned about your engine, and clears the radio presets. If you have a Delco-Loc or Theft Loc II radio, make sure you follow the procedure to unlock the radio protection before disconnecting the battery. This five minutes is also just about long enough to clean both battery cables. Reconnect the battery. When you first start the engine after clearing the ECM, the engine will operate with base parameters programmed into the ECM PROM. These parameters may not be optimum for your engine, but the ECM will enter a Block Learn Mode soon after the engine is warm and enters Closed Loop Mode. The ECM will write new data tables specific to your engine and will eventually rely on those tables instead of the base tables of the factory program. You can expedite this process by driving the car for 20 minutes under varying conditions to allow the ECM to initialize. Or you can wait and drive the car normally at your convenience. The BLM tables are constantly being updated as sensor input ranges change, but the greatest change will occur within the first twenty minutes of Closed Loop operation.
quote:Originally posted by Vader
Actually, the jumper (or any resistance below 500 ohms) can be inserted after the engine is running to invoke the Diagnostic / Field Service Mode. Attempting to start an engine while in Diagnostic Mode (diagnostic request terminal 'B' grounded, engine off) can damage the firmware (not always does, but can).
Diagnostic mode will will display malfunctions stored in nonvolatile memory and perform other functions as described below when the diagnostic display mode is enabled. This mode requires that the diagnostic request line be grounded and that the engine not be running (see EST).
Solenoid Energization
When the diagnostic display mode is enabled and the battery voltage is less than 16.9V, the diagnostic control logic will energize the AIR control, AIR select, TCC, EGR solenoid, A/C and EVAP canister purge solenoids. In addition, the idle air control motor will be continuously pulsed to retract while in diagnostic display mode.
The solenoid energization function is capable of operating without a calibration PROM installed in the ECM. The purpose of this function is to allow a means to force the ECM to energize its outputs for troubleshooting purposes, and to provide a means for exercising the ECM output devices during burn-in at the factory.
Malfunction Code Suppression
While the diagnostic display mode is enabled, the diagnostic control logic will force the diagnostic control counter to zero. This action has the effect of preventing new malfunctions from being logged into nonvolatile memory while the diagnostic display mode is enabled.
Malfunction Code Display
Each malfunction condition is associated with a two digit code number. When the diagnostic display mode is enabled, the diagnostic control logic will flash the check engine lamp in a logical sequence to depict the two digit code associated with each malfunction stored in nonvolatile memory.
Each code displayed will consist of a number of flashes representing the first digit followed by a short pause, followed by a number of flashes representing the second digit, followed by a long pause indicating the end of the code.
Each stored code is displayed three times before proceeding to the next code. After all malfunction codes stored in nonvolatile memory have been thus displayed, the entire flashing sequence is repeated.
Field Service Mode will display some basic ECM information via the SES lamp. If the ECM is in Open-Loop mode, the SES light will flash rapidly, about 2½ times per second. If it's in Closed-Loop mode, it will flash about once per second. When in Closed Loop mode, flashing less than once per second indicates the ECM is enriching the mixture above the 128 count base line. Flashing more than once per second indicates the ECM is leaning the mixture below the 128 base line.
Inserting a 3.9K ohm resistance in the diagnostic request pin to ground will invoke Factory Test Mode or Backup Fuel and Spark Mode ("Limp Home Mode"), which forces the ECM to use predetermined fuel calculations in the ECM PROM instead of the learned inputs in active RAM. Backup fuel is usually around 12:1 or richer from the factory. Tthe ECM will turn on the check engine lamp in this mode.
A 10K ohm resistance in the diagnostic terminal to ground will invoke the factory End of Line Test Mode, or ALDL Mode. When the assembly line diagnostic mode is detected, the fuel logic will bypass the closed loop time criteria. The fuel logic will enter closed loop mode as soon as the coolant temperature and oxygen sensor thresholds are met. There will be no reset of the integrator function. The IAC will use the calibration memory table value corresponding to a battery voltage of 8 volts, bypass certain criteria for RPM closed loop enable, and bypass coolant restrictions for enabling IAC kick-down mode. The EST system will disable the Burst Knock logic and bypass the RPM and coolant temperature criteria for ESC retard enable. That will force the engine into a condition where spark knock should occur if the throttle is suddenly opened (Burst Knock). Additionally, if ALDL mode has been enabled longer than a PROM timer value, the timer will be removed from the spark advance calculation. The TCC logic will allow the TCC to be enabled sooner and without regard to the CTS input.
Actually, the jumper (or any resistance below 500 ohms) can be inserted after the engine is running to invoke the Diagnostic / Field Service Mode. Attempting to start an engine while in Diagnostic Mode (diagnostic request terminal 'B' grounded, engine off) can damage the firmware (not always does, but can).
Diagnostic mode will will display malfunctions stored in nonvolatile memory and perform other functions as described below when the diagnostic display mode is enabled. This mode requires that the diagnostic request line be grounded and that the engine not be running (see EST).
Solenoid Energization
When the diagnostic display mode is enabled and the battery voltage is less than 16.9V, the diagnostic control logic will energize the AIR control, AIR select, TCC, EGR solenoid, A/C and EVAP canister purge solenoids. In addition, the idle air control motor will be continuously pulsed to retract while in diagnostic display mode.
The solenoid energization function is capable of operating without a calibration PROM installed in the ECM. The purpose of this function is to allow a means to force the ECM to energize its outputs for troubleshooting purposes, and to provide a means for exercising the ECM output devices during burn-in at the factory.
Malfunction Code Suppression
While the diagnostic display mode is enabled, the diagnostic control logic will force the diagnostic control counter to zero. This action has the effect of preventing new malfunctions from being logged into nonvolatile memory while the diagnostic display mode is enabled.
Malfunction Code Display
Each malfunction condition is associated with a two digit code number. When the diagnostic display mode is enabled, the diagnostic control logic will flash the check engine lamp in a logical sequence to depict the two digit code associated with each malfunction stored in nonvolatile memory.
Each code displayed will consist of a number of flashes representing the first digit followed by a short pause, followed by a number of flashes representing the second digit, followed by a long pause indicating the end of the code.
Each stored code is displayed three times before proceeding to the next code. After all malfunction codes stored in nonvolatile memory have been thus displayed, the entire flashing sequence is repeated.
Field Service Mode will display some basic ECM information via the SES lamp. If the ECM is in Open-Loop mode, the SES light will flash rapidly, about 2½ times per second. If it's in Closed-Loop mode, it will flash about once per second. When in Closed Loop mode, flashing less than once per second indicates the ECM is enriching the mixture above the 128 count base line. Flashing more than once per second indicates the ECM is leaning the mixture below the 128 base line.
Inserting a 3.9K ohm resistance in the diagnostic request pin to ground will invoke Factory Test Mode or Backup Fuel and Spark Mode ("Limp Home Mode"), which forces the ECM to use predetermined fuel calculations in the ECM PROM instead of the learned inputs in active RAM. Backup fuel is usually around 12:1 or richer from the factory. Tthe ECM will turn on the check engine lamp in this mode.
A 10K ohm resistance in the diagnostic terminal to ground will invoke the factory End of Line Test Mode, or ALDL Mode. When the assembly line diagnostic mode is detected, the fuel logic will bypass the closed loop time criteria. The fuel logic will enter closed loop mode as soon as the coolant temperature and oxygen sensor thresholds are met. There will be no reset of the integrator function. The IAC will use the calibration memory table value corresponding to a battery voltage of 8 volts, bypass certain criteria for RPM closed loop enable, and bypass coolant restrictions for enabling IAC kick-down mode. The EST system will disable the Burst Knock logic and bypass the RPM and coolant temperature criteria for ESC retard enable. That will force the engine into a condition where spark knock should occur if the throttle is suddenly opened (Burst Knock). Additionally, if ALDL mode has been enabled longer than a PROM timer value, the timer will be removed from the spark advance calculation. The TCC logic will allow the TCC to be enabled sooner and without regard to the CTS input.
Last edited by razor; Dec 30, 2004 at 09:39 PM.
Thread Starter
Supreme Member
Joined: Jul 1999
Posts: 2,149
Likes: 4
From: Mims, Florida
Car: '87 IROCZ
Engine: 395 ZZ4
Transmission: ProBuilt 700R4
Axle/Gears: 9 bolt 3.70s
So the answer is, after removing the connector from the IAC, you turn the key off and then remove the paper clip.
Thank you.
Thank you.
Senior Member
Joined: Jul 2002
Posts: 631
Likes: 2
From: Saskatchewan
Car: 1992 GTA
Engine: LS1
Transmission: T56
Axle/Gears: 4.10
Originally posted by doc
So the answer is, after removing the connector from the IAC, you turn the key off and then remove the paper clip.
Thank you.
So the answer is, after removing the connector from the IAC, you turn the key off and then remove the paper clip.
Thank you.
I thought it best to let education rule over opinion in this instance. I was going to actually type my own shorter reply but it would have been plagerism. Besides there is some good info in there that maybe isn't directly related to diagnostic mode but has some relevance.Okay now I am off to find rum befor the stores close. Have a happy New Years....
Thread Starter
Supreme Member
Joined: Jul 1999
Posts: 2,149
Likes: 4
From: Mims, Florida
Car: '87 IROCZ
Engine: 395 ZZ4
Transmission: ProBuilt 700R4
Axle/Gears: 9 bolt 3.70s
Yep, Happy New Years to all !!!!!!!!!!!!!
And razor, thank you for the post above (the long one). It has alot good stuff in it and very informative. Its the most complete instructions that I have evr seen.
And razor, thank you for the post above (the long one). It has alot good stuff in it and very informative. Its the most complete instructions that I have evr seen.
Junior Member
Joined: Jan 2002
Posts: 98
Likes: 0
Car: '87 Pontiac Trans Am GTA
Engine: 350 5.7L TPI (L98)
Transmission: 700R4
I have a question about this. when I have key on but not running and I hook up my autoxray scan tool and read TPS voltage @.54 volts, then start engine reading jumps to .56 volts. is this normal?.. and so should I have it read .54 volts while running or with key on engine off?
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