Just today after starting up the car and warming it up for about 10 minutes I started driving and started to get small backfires only when slowing down to around 20 mph or so. I noticed one of the new plug wires I put on (msd) has been melted by the headers. Could this be my problem. Havent had time to check it out yet but thought I'd post on here for some suggestions. Recently I changed the plugs and wires(ngk 55's) because one was fouled. The car has some of the same symtoms as before. I'm thinking maybe the wire is melted through to the actual wire and is against the header. Hope thats all it is anyway. Any suggestions welcome.

 

The melted plug wire can without a doubt cause your backfire problems.....

 

I'm wondering if what you are hearing is a misfire rather than a backfire. A true backfire is caused by combustion when the exhaust valve is open. A short to header won't throw the spark over to another plug and cause it to fire during an exhaust valve being open.

You definitely need to attend to any wire that looks like it has suffered mechanical damage. If you have a volt ohmeter you can also check the resistance of each wire. Anything under about 600 ohms is good.

 

Get some "Koolsox" for those wires. I have them and no issues. They work great and are cheap insurance for burning wires..........

 

Besides the Koolsox you also need to put the metal shrouds that were on the stock wires onto the MSD wires

 

Original metal shrouds wont work with my MSD wires. When I had a plug wire burn through , not the MSD's, the check engine light came on.
Fred K.

 

My check engine light is on. Heres the deal. I had heads,cam etc done at ARE a few years back. Ever since then the check engine light has been on. I believe they even gave me an explanation of why. I forget now what it was. By the way they did a great job and I am in no way dissing them. Anyway, a month ago after sitting at a train for 15 minutes my car started running poopiety. I noticed a plug wire was totally unattached from the coil pack. I had quite a few miles on the plugs and wires so I decided to change them myself(for the first time). It went well and I had no problems realy. I put in the ngk ix's or whatever with the factory gapping(dont know what it was)and the msd wires. Well after that the check engine light went off for the first time in about 2 or 3 years, only to come back on all the time about a week and a half later. Now the car is running poopiety like it was before the plug change plus I am getting this backfiring or whatever. I checked the wires and they seem to be attached well. The one is melted a little but not even through the insulation. Short of replacing all the plugs again I dont know what to do. Should the plugs be bad after 1 month. The day I first noticed this I had let the car warm up a little longer than usual. Any suggestions please fire away(no pun intended). I dont know what else to do and dont feel confident taking it to a dealer expecially after all the mods.

 

My first suggestion would be to pull the codes to see what the CPU is telling you.
http://www.stengel.net/diccodes.htm

 

ok. The codes read.
10 pcm
p0141 hc

40 bcm
b2723 h

60 ipc
b0521 h

a6 scm
b2605 h

b0 rfa
u1096 h
u1064 h
u1016 h

Any help interpertating these appreciated.

 

p0141hc:
CIRCUIT DESCRIPTION
The PCM supplies a bias voltage (approximately 450 mV ) on the Heated Oxygen Sensor (HO2S) signal high and low circuits. When the ignition is turned to the ON position, battery voltage is supplied to the HO2S heater. As the heater reaches operating temperature, the HO2S voltage responds by changing from a bias voltage range to normal operation. Typically, as the HO2S reaches operating temperature, the HO2S voltage goes from a bias voltage to a voltage below 300 mV . Depending on the exhaust gas content, it is possible for the HO2S voltage to go above 450 mV .

The PCM will run the heater test only on a cold start (depends on cumulative air flow) and only once an ignition cycle. When the engine is started the PCM monitors the HO2S voltage. When the HO2S voltage goes above or below the bias range threshold, the PCM will determine how much time it took. If the PCM detects that it took too much time for the HO2S to enter into the normal operating range, a DTC sets. The time it takes the HO2S to reach the operating temperature is based on the amount of air flow into the engine.

CONDITIONS FOR RUNNING THE DTC


DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0125, P0200, P0335, P0336, P0351-P0358, P1120, P1220, P1221, P1258 are not set.
The intake air temperature and engine coolant temperature are less than 50°C (122°F) and are within 8°C (14.5°F) of each other at engine start-up.
The ignition voltage is between 10.0 volts and 18.0 volts .
The AIR and the Catalyst diagnostics are not active.
CONDITIONS FOR SETTING THE DTC
The HO2S voltage remains between 300 mV and 700 mV for a predetermined amount of time (depends on engine coolant temperature and air flow).

ACTION TAKEN WHEN THE DTC SETS


The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC


The PCM turns the malfunction indicator lamp (MIL) OFF after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A last test failed (current DTC) clears when the diagnostic runs and does not fail.
A History DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
Use a scan tool in order to clear the MIL/DTC.
DIAGNOSTIC AIDS

IMPORTANT:


Remove any debris from the PCM/TAC module connector surfaces before servicing the PCM/TAC module. Inspect the PCM/TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM/TAC modules.
For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A. Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Diagrams.
The heater diagnostic only runs on a cold start and only runs once per ignition cycle.
An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Wiring Repairs in Diagrams.
For an intermittent condition, refer to Symptoms. See: Diagnostic Information and Procedures\Symptoms
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.


Allow the engine to cool, before proceeding with this diagnostic table. The HO2S may be at the operating temperature and no drop or rise in the HO2S voltage would occur. If the HO2S voltage stays between 300-700 mV , this indicates the HO2S heater is inoperative.
If more than one HO2S heater DTC is set, this is a good indication that the HO2S fuse is open. Inspect all the related circuits going to all of the heated oxygen sensors for a short to ground. If all wiring is OK, it may be necessary to disconnect each HO2S one at a time to locate a shorted sensor.
This step verifies whether B+ supply is available at the sensor.
This step verifies whether a ground is available at the sensor.
This step verifies whether the HO2S heater element is internally open.
Inspect the ignition feed circuits at the Underhood Electrical Center for poor connections.
Inspect the splice pack for the ground circuits for an open circuit. A condition at the splice pack sets more than one heater DTC.

B2723:
CIRCUIT DESCRIPTION
The BCM supplies a 5 volt signal and a ground circuit for the PASS-Key(R) system. This allows the BCM to detect PASS-Key(R) resistance values. Inserting the PASS-Key(R) (with resistor pellet) in the ignition lock cylinder completes the PASS-Key(R) circuit. Contacts in the ignition lock cylinder mate with the pellet contacts. The BCM compares the resistance value of the key pellet to the valid resistance programmed into the BCM. If the proper resistance value is read, the BCM allows the following functions to occur:


The theft deterrent relay to energize.
The steering column to unlock.
The BCM sends a message through the serial data line to the PCM to allow fuel enable processing to occur. If the resistance value is incorrect, a malfunction is present and a DTC will set.
CONDITIONS FOR SETTING THE DTC


The voltage level sampled at the BCMs PASS-Key(R) signal circuit is high, signaling that an invalid PASS-Key(R) resistance was detected, and a short to voltage or an open circuit is present.
This condition must be present for 1 second .
ACTION TAKEN WHEN THE DTC SETS


Stores a DTC B2723 in the BCM memory.
Sends a message to the IPC to display the SECURITY indicator.
The BCM will disable the theft deterrent relay.
The PCM will not allow fuel enable processing to occur.
Disables sampling of the PASS-Key(R) resistance for a time-out period of 3 minutes .
Does not disarm an armed UTD system
The steering column remains in the locked position.
CONDITIONS FOR CLEARING THE DTC


This DTC requires an ignition cycle in order to change from current to history.
The BCM detects a valid PASS-Key® resistance value on the PASS-Key(R) signal circuit.
A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
Use the IPC clearing DTCs feature.
Use a scan tool.
DIAGNOSTIC AIDS


The following conditions may cause an intermittent malfunction:
There is an intermittent 0 en or short to voltage in the PASS- Key(R) signal or ground circuit.
There are poor connections at the BCM or the ignition switch connector.
The PASS-key® resistor is open.
The ignition lock cylinder key contacts or the PASS-key® resistor is dirty or loose.
If the key resistor pellet is incorrect, there will be no BCM outputs to the theft deterrent relay or to the PCM. This state will last about 3 minutes . If a key is inserted, or the ignition is turned ON again before the 3 minute time frame is complete, the timer will reset to 3 minutes . Disconnecting the battery will not clear the timer sequence, but the timer will reset to 3 minutes when the battery power is restored. Even if a proper key is inserted during one of the time periods, the vehicle will not start until the total time period has lapsed.

Clean away any dirt or grease from the key resistor. The foreign substances could interfere with the key detection circuit and set a DTC.
If there is an open or a short to voltage on the PASS-key(R) signal or ground circuit. The vehicle will exhibit a no crank condition.
Check for any poor connections at the BCM and at the ignition lock cylinder. A poor connection can cause an open, a short, incorrect PASS Key(R) resistance, or an intermittent malfunction. If the DTC is a history DTC, the problem may be intermittent. Perform the tests while moving the related wiring, the connectors, and the key. This can often cause the malfunction to appear. Refer to intermittents and Poor Connections. See: Intermittents and Poor Connections
TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.


Tests PASS-key(R) Resister Signal data using a scan tool.
Tests the PASS-key(R) Resister Signal data with the PASS-key(R) ignition switch connector disconnected. The scan tool will display PASS-key(R) Resister Signal voltage as 5 volts with the PASS-key(R) ignition switch connector disconnected.
Tests the PASS-key(R) Resister Signal data with a jumper wire between the signal and ground circuit. The scan tool will display PASS-key(R) Resister Signal voltage as 0 volts with the PASS-key circuits jumpered.
When the BCM is replaced, use a scan tool to perform the BCM RPO Reprogram procedure. Refer to BCM Programming/RPO Configuration

b0521:
CIRCUIT DESCRIPTION
The Instrument Panel Cluster (IPC) receives engine RPM information from the Powertrain Control Module (PCM). Engine RPM input information is obtained from the PCM on a dedicated engine speed input to the IPC. The IPC also receives engine RPM data on the serial data line. The PCM is responsible for processing and sending engine RPM data to the IPC. The IPC will only display the engine RPM data that was sent by the PCM. The IPC monitors the engine RPM output information sent from the PCM for an out of range condition.

CONDITIONS FOR SETTING THE DTC


The IPC detects engine RPM information sent from the PCM over 7400 RPM.
Condition must be present for 1 second .
ACTION TAKEN WHEN THE DTC SETS


Stores a DTC B0521 in the IPC memory.
The IPC will display engine RPM at 7400 RPM.
No driver warning message will be displayed for this DTC.
CONDITIONS FOR CLEARING THE DTC


The IPC detects engine RPM information sent from the PCM under 7400 RPM.
A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
Use the IPC clear DTC feature.
Use a scan tool.
DIAGNOSTIC AIDS


The following conditions may cause an intermittent malfunction to occur:
The PCM is unable to process the correct RPM data.
Intermittent or erratic RPM signal sent from the PCM.
Test drive the vehicle and check for proper tachometer operation. If the IPC is unable to display the proper engine RPM, use a scan tool to display the PCM engine RPM data. If the PCM is not sending the proper engine RPM data to the IPC, then the PCM and engine RPM circuit must be diagnosed first before diagnosing the IPC.
Always check for proper tachometer circuit operation by displaying PCM engine RPM data and checking for stored VSS DTCs with a scan tool before attempting to diagnose a DTC B0521.
If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur.
TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.


Tests for any engine speed (tachometer) DTCs stored in the PCM. Any engine speed (tachometer) DTCs stored in the PCM may cause a DTC B0521 to set in the IPC.
Tests the tachometer operation. All tachometer malfunctions must be diagnosed and corrected first.
Tests for an open, short to voltage, or short to ground in the engine speed (tachometer) signal circuit.

b2605:CIRCUIT DESCRIPTION
The memory seat functions, are operated when voltages from the LH seat switch are first applied to the LH Seat Control Module (SCM). The SCM then stores the voltage appearing at the front vertical position sensor signal wire when either memory push button is pressed.

The SCM provides a steady 5 volt supply (CKT 1985) and a ground (CKT 782) to the front vertical position sensor. The front vertical position sensor, which is a variable resistor, provides a return voltage on the signal wire (CKT 557) to the SCM. Depending upon the location of the seat motor, the voltage in the signal wire varies from 0.1 to 4.78 volts . When one of the memory buttons is pressed, the SCM applies voltage to the motor until the position sensor voltage equals the stored value. The seat will then have returned to the stored vertical position.

CONDITIONS FOR SETTING THE DTC
The front vertical position sensor input, to the SCM, is under 0.1 or over 4.78 volts for 2 seconds or more.

ACTION TAKEN WHEN THE DTC SETS


Stores a history DTC B2605 in the SCM memory.
This DTC can only be set as a history code even if the malfunction is current.
No driver warning message will be displayed for this DTC.
The memory operation/function of the faulted position sensor is disabled.
CONDITIONS FOR CLEARING THE DTC


The front vertical position sensor input, to the SCM, is within 0.1-4.78 volts for 2 seconds or more.
Using the DTC clearing feature in the IPC.
Using a scan tool.
DIAGNOSTIC AIDS


If the DTC does not reset after the code is cleared, then the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur. Refer to Testing for Intermittent and Poor Connections in Diagrams.
The following conditions may also cause an intermittent malfunction:
There is an intermittent open, short to ground or battery in CKTs 557 or 1985.
There is an intermittent open or short to battery in CKT 782.
The front vertical position sensor is open or shorted internally.
If the SCM is unable to determine the correct vertical position, manual power seat functions will still operate, but the SCM will not be able to recall the correct seat memory settings.
Using a scan tool, select SCM data display and monitor the front vertical position data. Move the power seat vertically in both directions while monitoring the position sensor data. The voltage range should vary and stay between 0.1-4.78 volts depending on the position of the seat. This checks if the seat front vertical position sensor is open or shorted in different positions.
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:


This test checks if a DTC B2605 stored in the SCM memory.
This test checks the LH seat front vertical position sensor voltage using a scan tool. Normal position sensor voltage range is between 0.1-4.78 volts .
This test checks if the SCM is sending the correct supply voltage to the position sensor. The supply voltage measured must be between 4.0-5.5 volts .
This test checks for an open or short to voltage in CKT 782 or in the SCM internal ground circuit.


u1096 h
u1064 h
u1016 h
are meaning less.

 

I would check your wires. My buddy had a problem recently with a bad wire. Looked ok, but turned out to be messed up. Replaced them and the car ran great.

 

so even though they worked great for a month you think I should replace them as a start. Also thanks for the info on the codes. Are any of them related to the backfiring?

 

I have Koolsox and NO metal shrouds without ANY issues. I run Taylor 10.4 mm wires without shrouds and they are fine.

 

Well I replaced the six easy wires yesterday and got two backfires within a few minutes then nothing for the rest of the night. The car is still driving crappy. Kind of sputtery. Less power also. Is it possable the plugs are a problem? Going to get codes and replace the other two wires right now. Also I put the koolsox on them.

 

Replaced the last two wires and the check engine light went out and the car is running awsome again. Still a fishy situation. Like I've said before. When I first got my car back from ARE the check engine light was on. It stayed on for 3 years. Then I changed the plugs and wires and it went out for about a week and a half. Then about three weeks after that the car started to run crappy again. I changed the wires again and used koolsox(or some version of them). Everything was fine for about a day and a half. Now the check engine light is on but everything is still running good. Not sure if it will be a problem or not. Any insight into this situation is welcome.

 

If you clear the codes in the PCM, which ones will re-appear during a nice little drive?

My guess at the code is that it is a O2 sensor code that is unrelated to the backfiring problem. Back in the day when you had your heads/cam package done it was not as easy to dial out the 02 codes that like to pop up occasionally from most cars with long tube headers, so it might not have been done at the time.

 

with MattG

Clear all of the codes and drive her for most of the day. Read the codes and re-post. We can work from there!

BC