5.3l silverado misterious DTC

[asilverblazer]

I wouldn't spend money on sensors until a diagnosis confirms they are faulty.

[Larsson]

Today I got a new check engine light. This is the freezeframe. I noticed that the downstream O2 sensors give different voltages now. So maybe it was just " domb luck"?

 

I'm going to change all 4 of them and go from there.

[asilverblazer]

Conditions for Setting the DTC

The correction limit for a condition causing a rich or lean air/fuel ratio has been exceeded.

Diagnostic Aids

• The post catalyst fuel trim diagnostic is very sensitive to heated oxygen sensor (HO2S) design. A non-OE sensor or an incorrect part number may cause a DTC to set.
• Certain aftermarket air filters may cause a DTC to set.
• Certain aftermarket air induction systems or modifications to the air induction system may cause a DTC to set.
• Certain aftermarket exhaust system components may cause a DTC to set.

Circuit/System Verification

1. Ignition ON.
2. Verify no other HO2S or fuel trim DTC is set.
   • If any other HO2S or fuel trim DTC is set
     Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
    
   • If no other HO2S or fuel trim DTC is set
   
   
3. Verify DTC P2096, P2097, P2098, or P2099 is not set.
   • If a DTC is set
     Refer to Circuit/System Testing.
    
   • If no DTC is set
   
   
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed in the Freeze Frame/Failure Records data.
5. Verify DTC P2096, P2097, P2098, or P2099 is not set.
   • If a DTC is set
     Refer to Circuit/System Testing.
    
   • If no DTC is set
   
   
6. All OK.

Circuit/System Testing

Verify none of the conditions listed below exist:

P2096 or P2098

• Air intake duct collapsed or restricted.
• Air filter dirty or restricted.
• Contamination of the mass air flow sensor with oil or other foreign material
• Objects blocking the throttle body.
• Excessive fuel in the crankcase. Change engine oil as necessary.
• Rich fuel injectors. Refer to Fuel Injector Diagnosis.
• Excessive fuel system pressure. Refer to Fuel System Diagnosis.
• Fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis.
• Fuel saturation of the evaporative emissions (EVAP) canister.
• Stuck open or leaking EVAP purge valve.
• Restricted exhaust. Refer to Symptoms - Engine Exhaust.
• Improper operation of the crankcase ventilation system.

P2097 or P2099

• Exhaust system leaks. Refer to Symptoms - Engine Exhaust.
• Split, kinked or improperly connected vacuum hoses.
• Contamination of the mass air flow sensor with oil or other foreign material
• Insufficient fuel in the tank.
• Leaks in the air induction system and air intake ducts.
• Missing air filter element.
• Cracked evaporative canister.
• Evaporative pipes plugged, obstructed, or leaking.
• Crankcase ventilation system leaking.
• Engine vacuum leaks.
• Low fuel system pressure. Refer to Fuel System Diagnosis.
• Contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis.
• Lean fuel injectors. Refer to Fuel Injector Diagnosis.

[asilverblazer]

Nothing in the diagnosis of that code indicates replacing an O2 sensor. The O2 sensor is telling you something else is wrong based on its readings.

 

Don't shoot the messenger.

[Larsson]

According to my dianostic check the troublecodes are p2097 and p2099. The last time after I reset the dtc only a p2097 popped up. As you can see in the last picture of the freezeframe. 

Your dianostic aid is very helpfull but the links don't work here in holland. For example, when I click on the "fuel system diagnosis" , I get a no access message on my computer. It's like the website is blocked off. Or maybe it's only for people in the US? I don’t know.

 

Is there perhaps a different way to check the fuel and injector system? Maybe a different link?

 

Thanks for the great input by the way.

[asilverblazer]

Quote

Circuit/System Description

The engine control module (ECM) supplies voltage to the fuel pump driver control module when the ECM detects that the ignition is ON. The voltage from the ECM to the fuel pump driver control module remains active for 2 s, unless the engine is in Crank or Run. While this voltage is being received, the fuel pump driver control module closes the ground switch of the fuel tank fuel pump module and also supplies a varying voltage to the fuel tank fuel pump module in order to maintain the desired fuel line pressure.

 

The fuel system is an electronic returnless on-demand design. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.

 

An electric turbine style fuel pump attaches to the fuel tank fuel pump module inside the fuel tank. The fuel pump supplies fuel through the fuel feed pipe to the high pressure fuel pump. The high pressure fuel pump supplies fuel to a variable-pressure fuel rail. Fuel enters the combustion chamber through precision multi-hole fuel injectors. The high pressure fuel pump, fuel rail pressure, fuel injection timing, and injection duration are controlled by the ECM.

Diagnostic Aids

Observe the Misfire Counters or perform the Fuel Injector Balance Test to help identify a leaking Fuel Injector. Refer toFuel Injector Balance Test.

Reference Information

Description and Operation

Fuel System Description

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

 

Control Module References for scan tool information

Special Tools

 

CH–37287–1A - Fuel Pressure Gauge Adapter

 

For equivalent regional tools, refer to Special Tools.

Circuit/System Verification

Note:

• Repair all fuel system related DTCs before performing this diagnostic.
• Inspect the fuel system for damage or external leaks before proceeding.
• Verify that adequate fuel is in the fuel tank before proceeding.
• The Fuel Pump Enable may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
• DO NOT perform the Fuel System Diagnosis if the engine coolant temperature is above 60°C (150°F). High fuel pressure readings may result due to hot soak fuel boiling. With the engine OFF, the fuel pressure may increase beyond the pressure relief regulator valve's setting point of 690 kPa (100 psi) ± 5 percent.

 

Note: The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant.

 

Warning: Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.

1. Ignition ON, engine OFF, command the Fuel Pump Enable ON several times with a scan tool.
2. Verify the scan tool Fuel Pressure Sensor parameter is between 320–580 kPa (46–84 psi) with the fuel pump running.
   • If less than 320 kPa (46 psi)
     Refer to Circuit/System Testing — Fuel Pressure Low.
    
   • If greater than 580 kPa (84 psi)
     Replace the G12 Fuel Pump.
    
   • If between 320–580 kPa (46–84 psi)
3. Verify that the fuel pressure decreases to 468–544 kPa (68–79 psi) after the fuel pump is turned off.
   • If the fuel pressure does not decrease to 468–544 kPa (68–79 psi)
     Replace the G12 Fuel Pump.
    
   • If the fuel pressure decreases to 468–544 kPa (68–79 psi)
   
   
4. Verify that the fuel pressure does not decrease greater than 34 kPa (5 psi) in 1 minute.
   • If the fuel pressure decreases greater than 34 kPa (5 psi)
     Refer to Circuit/System Testing — Fuel Pressure Leaks Down.
    
   • If the fuel pressure does not decrease greater than 34 kPa (5 psi)
   
   
5. Relieve the fuel pressure to 69 kPa (10 psi), refer to Fuel Pressure Relief.
6. Verify that the fuel pressure does not decrease greater than 14 kPa (2 psi) in 5 minutes.
   • If the fuel pressure decreases greater than 14 kPa (2 psi)
     Replace the G12 Fuel Pump.
    
   • If the fuel pressure does not decrease greater than 14 kPa (2 psi)
7. Operate the vehicle within the conditions of the customer’s concern while monitoring the Fuel Pressure Sensor parameter with a scan tool.
8. Verify the fuel pressure does not drop off during acceleration, cruise or hard cornering.
   • If the fuel pressure drops off
     Refer to Circuit/System Testing — Fuel Pressure Drops OFF.
    
   • If the fuel pressure does not drop off
   
   
9. If the fuel system components test normal, refer to Symptoms - Engine Controls , Fuel Injector Diagnosis , and Fuel Injector Balance Test for further diagnosis.

Circuit/System Testing

Fuel Pressure Low

1. Verify none of the conditions listed below exist:
   • Restricted fuel feed pipe
   • Restricted or plugged strainer
   • Poor connections at the fuel pump harness connector and the ground circuits.
    
   • If a condition exist
     Repair as necessary.
    
   • If a condition does not exist
   
   
2. Test or replace the G12 Fuel Pump.

Fuel Pressure Leaks Down

1. Ignition OFF, relieve the fuel pressure. Refer to Fuel Pressure Relief.
2. Install the CH–37287–1A - Fuel Pressure Gauge Adapter between the fuel feed pipe and the fuel rail.
3. Open both of the valves on the CH–37287–1A - Fuel Pressure Gauge Adapter .
4. Ignition ON, command the Fuel Pump Enable ON with a scan tool.
5. Close one of the valves on the CH–37287–1A - Fuel Pressure Gauge Adapter .
6. Verify that the Fuel Pressure Sensor parameter does not decrease greater than 34 kPa (5 psi) in 1 minute.
   • If the fuel pressure drops
     Test or replace the G12 Fuel Pump.
    
   • If the fuel pressure does not drop
   
   
7. Locate and replace the leaking Q17 Fuel Injector.

Fuel Pressure Drops OFF

1. Verify none of the conditions listed below exist:
   • Restricted fuel feed pipe
   • Restricted or plugged strainer
   • Poor connections at the Fuel Pump harness connector and the ground circuit.
    
   • If a condition exist
     Repair as necessary.
    
   • If a condition does not exist
   
   
2. Test or replace the G12 Fuel Pump.

 

[asilverblazer]

Quote

Circuit/System Description

The engine control module (ECM) supplies a separate high voltage supply circuit and a high voltage control circuit for each fuel injector. The ECM initially opens each fuel injector with 65 V. This high voltage is controlled by a boost capacitor in the ECM. During the 65 V boost phase, the capacitor is discharged through a fuel injector, allowing for initial fuel injector opening. The fuel injector is then held open with 12 V. The ECM varies the amount of time each fuel injector is open to provide proper combustion under all engine load conditions.

 

A fuel injector coil winding resistance that is too high or too low will affect the engine driveability. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.

Reference Information

Schematic Reference

Engine Controls Schematics

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Component Testing

Note:

• The resistance test must be performed at the fuel injector or mis-diagnosis will occur.
• The DMM and test leads must be calibrated to 0 Ω in order to prevent mis-diagnosis.

1. Test for 1.06 Ω +/− 10% @ 20°C (68°F) between the high voltage supply circuit terminal 2 and the high voltage control circuit terminal 1 at the Q17 Fuel Injector.
   • If not within the specified range
     Replace the Q17 Fuel Injector.
    
   • If within the specified range
   
   
2. Test for infinite resistance between each terminal at the Q17 Fuel Injector and the Q17 Fuel Injector housing/case.
   • If not infinite resistance
     Replace the Q17 Fuel Injector.
    
   • If infinite resistance
   
   
3. All OK, perform the Fuel Injector Balance Test.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

 

Fuel Injector Replacement

 

[asilverblazer]

I posted fuel system and fuel injector diagnostics.

 

They are from a subscription site.

 

It is critical to use genuine OEM injectors and not counterfeit or aftermarket parts if you determine injectors need replaced. 

Edited July 17, 2024 by asilverblazer

[asilverblazer]

Quote

 

Circuit/System Description

Two methods of testing fuel injector balance are available, the Active Fuel Injector Tester (AFIT) or a scan tool. The Active Fuel Injector Tester and SIDI adaptor connects to the engine control module harness connectors to test the high pressure fuel pump performance, fuel injector wiring, and fuel injector operation. The AFIT displays step by step instructions to precisely determine pressure drop of each fuel injector. The scan tool fuel injector balance test is performed while the engine is running at idle. The scan tool pressurizes the fuel rail to a predetermined pressure before each fuel injector is pulsed for a precise amount of time allowing a measured amount of the fuel to be injected. This causes a drop in the system fuel pressure that is recorded and used to compare each fuel injector.

Diagnostic Aids

• Monitoring the scan tool Cylinder 1 -8 Current Misfire Counters may help to isolate the fuel injector that is causing the condition.
• Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

 

Component Connector End Views

Description and Operation

 

Fuel System Description

Scan Tool Reference

 

Control Module References for scan tool information

Special Tools

• CH-47976 - Active Fuel Injector Tester
• CH-47976-500 - Active Fuel Injection Tester (AFIT) SIDI Adapter Kit

 

For equivalent regional tools, refer to Special Tools

Circuit/System Verification

1. Ignition ON.
2. Verify the scan tool Fuel Remaining parameter is greater than 10%.
   • If the Fuel Remaining parameter is less than 10%, add fuel to the fuel tank.
    
   • If the Fuel Remaining parameter is 10% or greater
3. Verify the scan tool ECT Sensor parameter is less than 60°C (140°F).
   • If the ECT Sensor parameter is greater than 60°C (140°F), allow the engine temperature to cool.
    
   • If the ECT Sensor parameter is 60°C (140°F) or less
4. Verify the battery is fully charged and all accessories are Off.
   • If the battery is not fully charged, charge or repair battery as necessary.
    
   • If the battery is fully charged
5. Preform the appropriate Fuel Injector Balance Test in Circuit System Testing.

Circuit System Testing

Fuel Injector Balance Test with Active Fuel Injector Tester

1. Ignition OFF, all vehicle systems OFF. Install the CH-47976 - Active Fuel Injector Tester and the CH-47976-500 - Active Fuel Injection Tester (AFIT) SIDI Adapter Kit , refer to the Active Fuel Injector Tester User Guide. It may take up to 2 minutes for all vehicle systems to power down.
2. Turn ON the Active Fuel Injector Tester and select the vehicle.
3. Ignition ON, perform the Injector Test with the Active Fuel Injector Tester.
   • If the Active Fuel Injector Tester aborts testing due to fuel pressure or fuel leak down
     Refer to Fuel System Diagnosis.
    
   • If the Active Fuel Injector Tester does not abort testing
4. Compare the test results with the appropriate recommended tolerance.
   • If any fuel injector exceeds the recommended tolerance
     Replace the appropriate Q17 Fuel Injector(s).
    
   • If all fuel injectors are within the recommended tolerance
5. Perform Fuel Injector Circuit Diagnosis.

Fuel Injector Balance Test with Scan Tool

 

Note: The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant.

 

Note: The engine speed must be between 600–1,000 RPM to perform this test.

Note: For engines with 2 banks of cylinders, only measure average pressure drop on cylinders that are on the same bank.

1. Ignition ON.
2. Command the Fuel Pump Enable ON with a scan tool.
3. Verify the fuel pressure is between 320–580 kPa (46–84 PSI) with the fuel pump running.
   • If not within 320–580 kPa (46–84 PSI)
     Refer to Fuel System Diagnosis.
    
   • If within 320–580 kPa (46–84 PSI)
4. Verify the fuel pressure does not decrease greater than 34 kPa (5 PSI) within 1 minute.
   • If greater than the specified value
     Refer to Fuel System Diagnosis.
    
   • If less than the specified value
5. Engine idling.
6. Verify the scan tool Fuel Rail Pressure Sensor 1 parameter is between 1.9–5.0 MPa (276–725 PSI).
   • If not between 1.9–5.0 MPa (276–725 PSI)
     Refer to Fuel System Diagnosis.
    
   • If between 1.9–5.0 MPa (276–725 PSI)
7. Select the Fuel Injector Balance function within the Control Functions menu of a scan tool.
8. Select and test a Q17 Fuel Injector. Repeat for each Q17 Fuel Injector.
9. Obtain and record a pressure drop value for each Q17 Fuel Injector.
10. Add all of the individual pressure drop values except for the fuel injector suspected of being faulty. This is the total pressure drop.
11. Divide the total pressure drop by the number of fuel injectors that were added together. This is the average pressure drop.
12. Multiply the average pressure drop by 0.20. This is the acceptable variance from the average pressure drop, 20%.
13. Verify the difference between any individual pressure drop and the average pressure drop is not greater than the acceptable variance.
    • If greater than the acceptable variance
      Replace the Q17 Fuel Injector.
     
    • If within the acceptable variance
14. Perform Fuel Injector Circuit Diagnosis.

 

Edited July 17, 2024 by asilverblazer

[asilverblazer]

Fuel injector balance test above.

[Larsson]

If you look at the fuelpressure which is around 360 kpa in the freezeframe,  do you guys think it is a bit low? And what about the fuelrailpressure?

[asilverblazer]

On 8/3/2024 at 3:26 PM, Larsson said:

If you look at the fuelpressure which is around 360 kpa in the freezeframe,  do you guys think it is a bit low? And what about the fuelrailpressure?

I think those are both with in spec.

 

[Larsson]

It seems that the check engine light only comes on when I do short trips of 3 miles or less. Like going to the supermarket at the other side of town and give grandma a lift. When I do longer trips of like 60 or 80 miles it has no issues at all. 

The coolant temperature hits 210°F at these short trips, especialy now it's summertime and the outside temperature hits 80°F or more.

 

I'm trying to apply the systemtest of

Asilverblazer but I'm still learning/ experimenting how all of the tests work in combination with hptuners. 

[Larsson]

I didn't had much time to do any testing on the truck past year. But I started again to solve the problem once and for all.

 

I think the high pressure fuel pump is a bit faulty. I did some testing to see if the long and short term fueltrim is ok.

With the engine warmed up I

first plugged the crankcase ventilation to see if the long term fuel trim stays in spec. It read -3.9% at idle.

Then I connected the crankcase ventilation and it read -10%. (Bank 1 and 2 read about the same percentage) So I think the high pressure fuelpump is leaking fuel in the oil.

 

When I turn on the ignition to check the fuelpressure it stays at 250 kpa. And at idle it bounces around 250 kpa and 460 kpa. Even at 3000rpm it doesn't go above maybe 380 kpa.

And the fuel rail pressure reads 400 to 500 kpa.

 

So I think I'm going to replace the high pressure fuel pump. It could be a faulty injector but because the fuelpressure is a bit low I think the best way to go is change the fuelpump. 

 

What do you guys think?

[Larsson]

After a few years tollerating the check engine light I got tired of it and fix it. After a dozen of hp tuner scans with the laptop it came clear that the problem occured ocasionally and not permanent. At one scan I saw the low side fuel pressure drop fast. The high pressure stayed more constant. At all the other scans it didn't occured. 

 

So I figured out that the high pressure fuel pump was dropping pressure at the low pressure side.

 

I replaced the high pressure fuel pump today and scaned it. No codes. I hope it is fixed now. It also was giving rich at the short and longtherm fueltrims. As before the replacement it was giving lean values all the time.

 

I keep you posted on the progress.