bai78
Surviving
Did anyone say check the TPS yet?
Help - running rough, new plugs, wires, cap and rotor
- Thread starter gulleyman
- Start date
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Der....what's a TPS? Sounds like a sensor or something right? Let me know and I'll have them check that out too.
SunlitComet
OBS Jedi-Do Good
Throttle position sensor located on the end of the throttle shaft use to provide angular measurement of same. It determines how far open the throttle is. If this was an issue it would pop A p-code on you. Any new ones to report?
I spoke to a guy that worked there today but wasn't the one working on my truck. He said he thought that they had gotten a timing code, replaced a sensor and they were test driving it again. Man I want my truck back 
I'll keep you all posted!
---------- Post added at 05:54 PM ---------- Previous post was at 04:51 PM ----------
Okay, so it's pulling a 1343A code, says that it's the distributor, crank sensor or timing chain. Also that the crank time and cam time is too far off. Says that it could also mean internal engine damage but he doesn't see how. He says the timing looks good though.
It's misfiring on five and seven at idle, then when RPM's get between 1500-2000 they start firing again but then we lose number six.
He changed the crank and cam sensors, swapped the wires and plugs around, checked compression, pulled the distributor and checked it, adjusted the timing again, checked the sweep (for TPS failure), checked all the wires to and from the ECM with an ohmeter...no luck
Says he's talked to about 15 other mechanics trying to figure it out and he's stumped. Said that one of them suggested that it must be the ECM because the misfire is so sparatic. He wants to trouble shoot the ECM next but doesn't have the equipment to do it. I suggested that we find a used ECM to swap it out and see if that does it, they're only $30 at the Pick and Pull if there's one there. Can the guys that do the custom tune's fix a busted ECM?
What do you guys think?
I'll keep you all posted!---------- Post added at 05:54 PM ---------- Previous post was at 04:51 PM ----------
Okay, so it's pulling a 1343A code, says that it's the distributor, crank sensor or timing chain. Also that the crank time and cam time is too far off. Says that it could also mean internal engine damage but he doesn't see how. He says the timing looks good though.
It's misfiring on five and seven at idle, then when RPM's get between 1500-2000 they start firing again but then we lose number six.
He changed the crank and cam sensors, swapped the wires and plugs around, checked compression, pulled the distributor and checked it, adjusted the timing again, checked the sweep (for TPS failure), checked all the wires to and from the ECM with an ohmeter...no luck
Says he's talked to about 15 other mechanics trying to figure it out and he's stumped. Said that one of them suggested that it must be the ECM because the misfire is so sparatic. He wants to trouble shoot the ECM next but doesn't have the equipment to do it. I suggested that we find a used ECM to swap it out and see if that does it, they're only $30 at the Pick and Pull if there's one there. Can the guys that do the custom tune's fix a busted ECM?
What do you guys think?
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SunlitComet
OBS Jedi-Do Good
Are you sure about the code it does not show up for gm vehicles in several places I looked but it does for a bmw. I am following closely. I have not done my injector spider yet. I to have a misfire in 5-7 as well as a MAF and one O2s according to a mechanic but I think I will buy on OTC scanner that reads mode 6 data before proceeding any further. My #5 plug has oily residue with no signs of firing.
If it is a p1345 type a then:
CIRCUIT DESCRIPTION
This DTC determines if the distributor is installed incorrectly, or if there is a mechanical malfunction in the engine. The DTC P1345 is a type A DTC.
CONDITIONS FOR SETTING THE DTC
When the engine is running, the cam sensor reference pulse is not detected at the correct relative position to the crankshaft position sensor pulse.
ACTION TAKEN WHEN THE DTC SETS
The Vehicle Control Module (VCM) turns on the Malfunction Indicator Lamp (MIL).
CONDITIONS FOR CLEARING THE MIL/DTC
The VCM turns the MIL off after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 40°F from the start-up coolant temperature and the engine coolant temperature exceeds 160°F during that same ignition cycle) or the scan tool clearing feature has been used.
If it is a p1345 type a then:
CIRCUIT DESCRIPTION
This DTC determines if the distributor is installed incorrectly, or if there is a mechanical malfunction in the engine. The DTC P1345 is a type A DTC.
CONDITIONS FOR SETTING THE DTC
When the engine is running, the cam sensor reference pulse is not detected at the correct relative position to the crankshaft position sensor pulse.
ACTION TAKEN WHEN THE DTC SETS
The Vehicle Control Module (VCM) turns on the Malfunction Indicator Lamp (MIL).
CONDITIONS FOR CLEARING THE MIL/DTC
The VCM turns the MIL off after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 40°F from the start-up coolant temperature and the engine coolant temperature exceeds 160°F during that same ignition cycle) or the scan tool clearing feature has been used.
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SunlitComet
OBS Jedi-Do Good
BTW a remand computer done by A1 Cordone for mine is $130 and some minor prom chip transfer and reprogramming eeprom.
You may be right about the code, he was trying to remember it off the top of his head. I'll find out for sure tomorrow. Will also find out if I can get that ECM for $30. Thanks for your input, hopefully we'll get this resolved soon
strungout2000
TYF Newbie
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this happened to me, i went to three different mechanics in a span of six months. I replaced every compenant imaginable (plugs, wires, cap, rotor, egr, CPS TPS ICU, intake manifold gaskets) and cut my cats out. The third and final mechanic finally fixed it, my heads were slightly warped so i said screw it and had him built up my topend while it was apart.
Do a vacuum test to see if ur cats are clogged, also moniter you IAT TPS and MAP sensor readings. And what plugs and gaps did u use? Also What type of distributor? Some distributors that are offered for the 5.7L vortec will not work properly. Also double check your timing either mechanically or with a scanner.
Once my heads were rebuilt and everything thrown back together, it runs like a dream.
Do a vacuum test to see if ur cats are clogged, also moniter you IAT TPS and MAP sensor readings. And what plugs and gaps did u use? Also What type of distributor? Some distributors that are offered for the 5.7L vortec will not work properly. Also double check your timing either mechanically or with a scanner.
Once my heads were rebuilt and everything thrown back together, it runs like a dream.
How much did it cost to do that? What does that involve, I'm pretty new at this
---------- Post added at 05:47 AM ---------- Previous post was at 05:45 AM ----------
I have no idea what this means...damn I feel dumb, help me out here sunlitcomet
SunlitComet
OBS Jedi-Do Good
If your compression test are fine and you have no vacuum leaks or fluid cross contamination I would not mess with the heads or manifolds.
As far as the computer goes, Alldata says:
For a 96 chevy tahoe, your vehicle may vary:
VCM REPLACEMENT/PROGRAMMING
Service of the VCM consists of either replacement of VCM or reprogramming of the EEPROM. If the diagnostics call for replacement of the VCM, it will be necessary to transfer the PROM and program the EEPROM.
NOTE : When replacing the production VCM with a service VCM (controller), it is important to transfer the broadcast code and production VCM number to the service VCM label. This will allow positive identification of VCM parts throughout the service life of the vehicle. Also transfer the PROM.
CAUTION : To prevent internal VCM damage, the ignition must be OFF when disconnecting or reconnecting power to the VCM (for example, battery cable, VCM fuse, jumper cables, etc.).
CAUTION : In order to prevent possible Electrostatic Discharge damage to the VCM, do not touch the connector pins or soldered components on the circuit board.
VCM REPLACEMENT/PROGRAMMING (WITH KNOCK SENSOR (KS) CALIBRATION PROM)
REMOVAL PROCEDURE
1. Disconnect the negative battery cable.
2. Remove the connectors from the VCM.
3. Remove the spring retainer off and over the rail of the VCM. Slide the VCM out of the bracket at an angle.
4. Remove the VCM access cover.
5. Remove the PROM/Knock Sensor (KS) module.
6. Inspect for the alignment notches of the KS Calibration PROM.
7. Carefully set it aside.
8. Do not open the KS Calibration PROM.
9. Remove the new VCM from the packaging. Check the service number in order to make sure it is the same as the defective VCM.
10. Remove the access cover.
NOTE
* The Knock Sensor (KS) module must be transferred to the replacement VCM.
* The replacement VCM is supplied without a EEPROM program, the replacement VCM must be programmed before the vehicle will run.
* Using the thumb and first finger, remove the KS Calibration PROM by gently squeezing each end of the blue KS Calibration PROM
* Do not remove the cover of the KS Calibration PROM. Use of an unapproved KS Calibration PROM removal methods may cause damage to the KS Calibration PROM or the socket.
INSTALLATION PROCEDURE
NOTE : Press only on the ends of the KS Calibration PROM. Gently press on the KS Calibration PROM until it is firmly seated in the socket. Listen for the click.
1. Align the notches of the KS Calibration PROM with the notches in the KS Calibration PROM socket.
2. Install the KS Calibration PROM in the KS Calibration PROM socket.
3. Install the access cover on the VCM.
4. Install the VCM in the engine compartment.
5. Install the connectors to the VCM.
6. The MIL, antilock and brake lamps will continue to be enabled until the VCM is programmed. Once the programming is complete, the lamps will turn off and normal operation will occur.
7. Connect the negative battery cable.
CAUTION : In order to prevent possible Electrostatic Discharge damage to the VCM, do not touch the connector pins or soldered components on the circuit board.
8. Proceed to the EEPROM programming .
EEPROM Programming:
CAUTION : The ignition should always be "off" when installing or removing the Vehicle Control Module (VCM) connectors.
1. Set-up:
o Battery is charged.
o Ignition is "ON."
o Battery/cig. lighter Connection secure.
o Data Link Connector (DLC) .
2. Refer to up-to-date Techline terminal/equipment user's instructions.
3. If Vehicle Control Module (VCM) fails to program, do the following:
o Check all VCM connections.
o check Techline terminal/equipment for latest software version.
o Try again to program the VCM. If it fails again, replace the VCM. Refer to VCM replacement . See: Control Module Replacement
4. Perform the Idle Air Control (IAC) valve reset procedure with the scan tool. use misc. test.
5. For a functional check perform one of the steps:
o Use the Techline terminal and equipment in order to perform the On-Board Diagnostic (OBD) System Check
o Refer to Powertrain OBD System Check . See: Testing and Inspection.
Btw if that distributor code is accurate then the mech can try this:
TEST PROCEDURE
The ignition timing cannot be adjusted. The distributor may need adjusting to prevent crossfire. To insure proper alignment of the distributor, perform the following:
1. With the ignition OFF, install a scan tool to the DLC.
2. Start the engine and bring to normal operating temperature. IMPORTANT: Cam Retard Offset reading will not be accurate below 1000 RPM.
3. Increase engine speed to 1000 RPM.
4. Monitor the Cam Retard Offset.
5. If the Cam Retard indicates a value of 0°+/-2°, the distributor is properly adjusted.
6. If the Cam Retard does not indicate 0°+/-2°, the distributor must be adjusted.
ADJUSTING PROCEDURE
1. With the engine OFF, slightly loosen the distributor hold down bolt. IMPORTANT: Cam Retard Offset reading will not be accurate below 1000 RPM.
2. Start the engine and raise engine speed to 1000 RPM.
3. Using a scan tool monitor Cam Retard Offset.
4. Rotate the distributor as follows:
4.1. To compensate for a negative reading, rotate the distributor in the counterclockwise direction.
4.2. To compensate for a positive reading, rotate the distributor in the clockwise direction.
5. Repeat step 4 until 0°+/-2°, is obtained.
6. Turn the ignition OFF.
7. Tighten the distributor hold-down bolt to 3 Nm (25 lb. ft.).
8. Start the engine, raise engine speed to 1000 RPM and recheck Camshaft Retard Offset.
As far as the computer goes, Alldata says:
For a 96 chevy tahoe, your vehicle may vary:
VCM REPLACEMENT/PROGRAMMING
Service of the VCM consists of either replacement of VCM or reprogramming of the EEPROM. If the diagnostics call for replacement of the VCM, it will be necessary to transfer the PROM and program the EEPROM.
NOTE : When replacing the production VCM with a service VCM (controller), it is important to transfer the broadcast code and production VCM number to the service VCM label. This will allow positive identification of VCM parts throughout the service life of the vehicle. Also transfer the PROM.
CAUTION : To prevent internal VCM damage, the ignition must be OFF when disconnecting or reconnecting power to the VCM (for example, battery cable, VCM fuse, jumper cables, etc.).
CAUTION : In order to prevent possible Electrostatic Discharge damage to the VCM, do not touch the connector pins or soldered components on the circuit board.
VCM REPLACEMENT/PROGRAMMING (WITH KNOCK SENSOR (KS) CALIBRATION PROM)
REMOVAL PROCEDURE
1. Disconnect the negative battery cable.
2. Remove the connectors from the VCM.
3. Remove the spring retainer off and over the rail of the VCM. Slide the VCM out of the bracket at an angle.
4. Remove the VCM access cover.
5. Remove the PROM/Knock Sensor (KS) module.
6. Inspect for the alignment notches of the KS Calibration PROM.
7. Carefully set it aside.
8. Do not open the KS Calibration PROM.
9. Remove the new VCM from the packaging. Check the service number in order to make sure it is the same as the defective VCM.
10. Remove the access cover.
NOTE
* The Knock Sensor (KS) module must be transferred to the replacement VCM.
* The replacement VCM is supplied without a EEPROM program, the replacement VCM must be programmed before the vehicle will run.
* Using the thumb and first finger, remove the KS Calibration PROM by gently squeezing each end of the blue KS Calibration PROM
* Do not remove the cover of the KS Calibration PROM. Use of an unapproved KS Calibration PROM removal methods may cause damage to the KS Calibration PROM or the socket.
INSTALLATION PROCEDURE
NOTE : Press only on the ends of the KS Calibration PROM. Gently press on the KS Calibration PROM until it is firmly seated in the socket. Listen for the click.
1. Align the notches of the KS Calibration PROM with the notches in the KS Calibration PROM socket.
2. Install the KS Calibration PROM in the KS Calibration PROM socket.
3. Install the access cover on the VCM.
4. Install the VCM in the engine compartment.
5. Install the connectors to the VCM.
6. The MIL, antilock and brake lamps will continue to be enabled until the VCM is programmed. Once the programming is complete, the lamps will turn off and normal operation will occur.
7. Connect the negative battery cable.
CAUTION : In order to prevent possible Electrostatic Discharge damage to the VCM, do not touch the connector pins or soldered components on the circuit board.
8. Proceed to the EEPROM programming .
EEPROM Programming:
CAUTION : The ignition should always be "off" when installing or removing the Vehicle Control Module (VCM) connectors.
1. Set-up:
o Battery is charged.
o Ignition is "ON."
o Battery/cig. lighter Connection secure.
o Data Link Connector (DLC) .
2. Refer to up-to-date Techline terminal/equipment user's instructions.
3. If Vehicle Control Module (VCM) fails to program, do the following:
o Check all VCM connections.
o check Techline terminal/equipment for latest software version.
o Try again to program the VCM. If it fails again, replace the VCM. Refer to VCM replacement . See: Control Module Replacement
4. Perform the Idle Air Control (IAC) valve reset procedure with the scan tool. use misc. test.
5. For a functional check perform one of the steps:
o Use the Techline terminal and equipment in order to perform the On-Board Diagnostic (OBD) System Check
o Refer to Powertrain OBD System Check . See: Testing and Inspection.
Btw if that distributor code is accurate then the mech can try this:
TEST PROCEDURE
The ignition timing cannot be adjusted. The distributor may need adjusting to prevent crossfire. To insure proper alignment of the distributor, perform the following:
1. With the ignition OFF, install a scan tool to the DLC.
2. Start the engine and bring to normal operating temperature. IMPORTANT: Cam Retard Offset reading will not be accurate below 1000 RPM.
3. Increase engine speed to 1000 RPM.
4. Monitor the Cam Retard Offset.
5. If the Cam Retard indicates a value of 0°+/-2°, the distributor is properly adjusted.
6. If the Cam Retard does not indicate 0°+/-2°, the distributor must be adjusted.
ADJUSTING PROCEDURE
1. With the engine OFF, slightly loosen the distributor hold down bolt. IMPORTANT: Cam Retard Offset reading will not be accurate below 1000 RPM.
2. Start the engine and raise engine speed to 1000 RPM.
3. Using a scan tool monitor Cam Retard Offset.
4. Rotate the distributor as follows:
4.1. To compensate for a negative reading, rotate the distributor in the counterclockwise direction.
4.2. To compensate for a positive reading, rotate the distributor in the clockwise direction.
5. Repeat step 4 until 0°+/-2°, is obtained.
6. Turn the ignition OFF.
7. Tighten the distributor hold-down bolt to 3 Nm (25 lb. ft.).
8. Start the engine, raise engine speed to 1000 RPM and recheck Camshaft Retard Offset.
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