FIRST GO WITH OBD!

JetJock

CCCUK Member
Hello again.
First, I dropped Fast Red in to Advanced Automotive Services in Newcastle on Friday for replacement dynamic balancer and some steering bits, and they were, as expected, super helpful, apparently very knowledgeable, and extremely reasonable on price. Thank you again, Stuart and the guys!

Today, having returned home yesterday, I had an engine management light illuminate while briefly doing (cough!) 40.
It stayed on, so, on return home, I decided now was the ideal time to try out the OBD that TeamZR1 had recommended, and which was delivered a couple of weeks ago.
Although the caption stayed on initially while I struggled, for the first time ever, to set up an OBD reader, it eventually extinguished while I was monkeying about with the laptop. Subsequently, another quick blast through the Highlands gave no repeat of the warning.
Attached is the readout from the OBD reader, and I'd be most grateful if anybody (hello, dear TeamZR1! - hope you're fine and dandy and well and happy, and READING THIS! :) ) could help with any translation, interpretation or general feedback and information from the .pdf.
e.g.
The first table MONITOR STATUS REPORT shows?
From "Mode $05 - Oxygen Sensors" I note that the rearmost 4 cylinders seem to be showing no air mass sensor info. Could this be related to me swapping out the plastic covers for new ones immediately before this ride? Could I have loosened some important wires?
I didn't clear the code in the OBD gizmo. Should I?
The MIL engine management light extinguished and hasn't yet come back. Job done? Or should I worry?
Can you give me any more information about what I can learn from this report, or from using the OBDLinkMX+ generally?

Thanks for any input, which is all very much appreciated.
 

Attachments

  • FAST RED DIAGNOSTIC REPORT 2 APR 2022.pdf
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Last edited:

Oneball

CCCUK Member
Your error code is P0101. This is for the MAF not doing as the ecumenical expects. I’d check you’ve not knocked a pipe or vacuum hose off so unmetered air is getting into the inlet.

Clear the code to see if it comes back.
 

teamzr1

Supporting vendor
Hi JetLock
First, even though I am thousands of miles from you, I can say you were a speeder and should be reported to the coppers ! :)
You were doing 118 MPH, but that is good enough to become a Team ZR-1 Corvette Racers member of our Big Balls Gang (BBG)

Although to stay in our group, we expect you to go faster next time !
BTW, with a spy of Onstar, it also can see and report all OBD -II data :-(

JetJocjC6DTC.jpg
 

teamzr1

Supporting vendor
OK, so now it is a JR's OBD-II class time :)
I may be giving you all a quiz later, so be on your toes ;-)

All vehicles in the USA starting in 1996 had to comply to federal SMOG rules and was the second version of OBD-I was pre-1996
so you're using a OBD-II scanner
OBD-II is tougher as to smog tests, so it has more functions in the PCM (Powertrain Control Module)
and has more feedback sensors which the PCM monitors

That allows OBD-II as you see to monitor and store lots of information as your seeing

Did you recently remove battery voltage or allowed the battery to get below like 12.5 volts, if so maybe one point and that is :
If you were to do a smog test, your 2005 C6 would fail as the on-board smog tests the PCM does, and the results are stored

These tests determine if the car passes or fails when having a smog shop test the car as it also uses OBD-II stored results
If the function tested is NOT in a completed state, then it is a FAIL
In a completed, stated is a PASS
As you see, some functions failed


But it could be that the way the feds wanted to protect on-board tests if forces the nameplates to flash all smog tests
back to a non-complete state IF the battery was disconnected ( dudes whose car would fail think resetting PCM hides the fails
but instead just F'd themselves by removing battery)
Or if the battery voltage is too low then tests results get flushed out
And so you see it reports vehicle is not ready to have smog test done by a official smog shop
So the question is did you do above ?

The report then points to why the DTC tripped the CEL (Check Engine Light)
Any DTC that begins with a P occurred within the PCM

In this case, a P0101
As mentioned, deals with the MAF



JetJock05C6DTC.jpg
 

JetJock

CCCUK Member
See, I told you I was rubbish with IT - I've obviously messed it up and introduced all sorts of errors into the readout...
I assume the speed recorded (when it's correct, unlike this one) is the speed at which the warning first appears? :)
Can you please explain what this means?
1648926846526.png
 

teamzr1

Supporting vendor
P0101 is defined as :

OBD-II Code P0101 is defined as a Mass Air Flow Sensor Circuit/Performance Malfunction
The Mass Airflow Sensor (MAF) measures the amount of airmass entering the engine.
This is important information the Engine Control Module (ECM) uses to calculate the proper amount of fuel for combustion and the amount of ignition timing advance. Code P0101 is set when this sensor's output becomes irrational and/or out of range.

P0101 Symptoms​

  • Check Engine Light will illuminate
  • In some cases, there may be no adverse conditions noticed by the driver
  • In other cases, there may performance problems, such as a lack of power on acceleration, "coughing," misfiring, and/or backfiring
  • Problems idling
  • Black smoke from the tail pipe and poor fuel mileage
  • Other codes may be triggered by the Mass Air Flow Sensor problem such as Oxygen Sensor and/or Fuel Trim Lean/Rich codes (P0130/P0136, P0131/P0137, P0132/P0138, P0135/P0155, P0171/P0174, P0172/P0175)

Common Problems​

  • Large vacuum leaks, split Intake Air Boot or PCV Hose, defective intake manifold gaskets
  • Mass Airflow Sensor (MAF)
  • Mass Air Flow Sensor circuit and or wiring problems
  • Defective Barometric Pressure Sensor
  • Dirty or contaminated Mass Air Flow Sensing wire or filament
  • PCM software needs to be updated

Common Misdiagnoses​

  • Oxygen Sensors
  • Mass Air Flow Sensor
  • Powertrain Control Module (PCM)

Polluting Gases Expelled​

  • HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog
  • CO (Carbon Monoxide): Partially burned fuel that is an odorless and deadly poisonous gas
  • NOX (Oxides of Nitrogen): One of the two ingredients that, when exposed to sunlight, cause smog

Want to Learn More?​

The purpose of the Mass Air Flow Sensor is to measure the amount of air entering the engine. The units of measurement are typically expressed in grams per second or GPS. The most commonly used Mass Air Flow Sensor employs a precisely heated wire that spans a vortex in front of the Throttle Body on the Intake Manifold. The PCM constantly adjusts the amperage to this Mass Air Flow Sensing wire in order to maintain a temperature that is precisely 100 degrees above the Intake Air Temperature. As intake air passes over this wire, it is cooled and within a few milliseconds, the PCM heats this wire back up to 100 degrees above the Intake Air Temperature Sensor reading.

The amount of amperage needed to maintain the Mass Air Flow Sensing Wire at this 100 degree level is converted by the PCM, using an algorithm, into a precise measurement (in GPS) of the amount of air entering the engine. The Powertrain Control Module then takes this information and calculates the amount of fuel for the injectors to mix with the incoming air charge in order to optimize combustion in the cylinders for the most power, while still maintaining maximum fuel economy and the lowest possible emissions. The PCM also uses the Mass Air Flow Sensor readings to influence the amount of Spark Advance to apply to each cylinder before it fires.

A few manufacturers install an Ultra Sonic Mass Air Flow Sensor that uses the changes of a sound wave inside a vortex to measure the amount of air coming into an engine. Some of the very old Mass Air Flow Sensors use a vane-like door for measurement. As the door gets pushed farther open by increases in the amount of intake air entering the engine, the movement gets translated into a rising voltage that the PCM converts into the GPS metric.

P0101 Diagnostic Theory for Shops and Technicians​

When the code P0101 is set, record the freeze frame data in fine detail. Then duplicate the code setting conditions on a test drive, paying particular attention to the GPS (or kilograms per hour) readings, load, MPH, and RPM. The best tool to use on this test drive is a data streaming scan tool that has factory quality and dedicated live data. Be sure to verify the code conditions before you advance to the next set of tests.
If You Can Verify the Code Setting Malfunction
If you can verify the code setting malfunction, then do a very careful visual inspection of the sensor and the connections. Visually inspect the Intake Air Boot for any signs of tears or cracking—you may have to pull on it to expose all of the sections. Also, do a very careful visual inspection of the PCV hoses and test the integrity of the Intake Manifold and its gaskets with a fuel substitute such as Propane gas. Verify that there is a 12-volt signal and a good ground to the sensor and that they meet the required times, per the manufacturer diagnostic documentation.
If these inspections don't diagnose the problem, then replace the Mass Air Flow Sensor with an OEM/OEM rebuilt unit. Aftermarket new or rebuilt Mass Air Flow Sensors are very inconsistent and often make the vehicle run worse and/or fail in ways that may be difficult to diagnose. The OEM units may not work properly either—some can fail as early as 100 miles.
_ If You Cannot Verify the Code Setting Malfunction _
If you cannot verify the code setting malfunction, then do a very careful visual inspection of the sensor and the connections. Visually inspect the Intake Air Boot for any signs of tears or cracking, you may have to pull on it to expose all of the sections. Also, do a very careful visual inspection of the PCV hoses and test the integrity of the Intake Manifold and its gaskets with a fuel substitute such as Propane gas. Verify that there is a 12-volt signal and a good ground to the sensor and that they meet the required times, per the manufacturer diagnostic documentation.
Watch the data stream of the Mass Air Flow Sensor while the engine idles and then slowly and carefully raise the engine RPM. The grams per second should slowly and smoothly rise. At idle and in "Park," the GPS should be around three to five. Next, drive the vehicle and do a Wide Open Throttle test (WOT) under maximum load. The GPS should go as high as 150 to 200, depending on the number of cylinders and displacement of the engine.
If the data stream test does not produce any conclusive results, then connect a lab scope to the signal wire with the voltage set at 20 and the time divisions at 100 milliseconds. Snap the throttle open and watch the signal. Do the same no-load idle test and WOT test at maximum load, described in the section above. The signal trace on lab scope should spike up to its maximum voltage without any "sharks' teeth," glitches, or drop outs in the quality of the signal. if you still cannot find the problem, here are some approaches to deploy next.
  • If you can receive authorization from the customer to keep the vehicle overnight, clear the code and test drive the vehicle by driving it home and then back to work in the morning, making sure that you are duplicating the code setting driving conditions on both trips. If the code still does not come back, you can give the customer the option of replacing the Oxygen Sensor as a diagnostic step since the sensor is the most likely problem and the code will presumably set again. If the customer declines, then return the vehicle with a clear description of the inspections and your findings plainly attached to the final copy of the repair order. Keep another copy for your own records in case you have to re-visit this inspection for any reason.
  • If this is an inspection for an emissions failure, most government programs suggest that you replace the sensor as a preventative measure so the vehicle won't remain in a highly polluting operational condition. After the Oxygen Sensor is replaced, the monitors will have to be re-set and this, too, will test most phases of the Oxygen Sensor system to ensure that the problem was solved. Be sure to verify that the Mode 6 test IDs and component IDs that pertain to fuel control are well within the parameter limits. If there is a problem with re-setting the monitors, continue the inspection until you find the root cause of the problem.
An "under reporting" Mass Air Flow Sensor can be a common cause of a code P0101. Essentially, this means that the Air Flow Sensor is telling the computer that much less air is entering the engine than actually is.
Since the oxygen sensors are telling the computer that more fuel is needed, this causes confusion in the computer because the Mass Air Flow Sensor is still saying there is too little air and the Oxygen Sensor is reporting that the mixture is still too lean. The computer tried to compensate, but since resolution is impossible, it sets the code. It is important to restate that the Oxygen Sensors are accurate—the fuel mixture is too lean. In this case, the Air Flow Meter or Sensor is inaccurately reporting the real amount of air entering the engine.
  • There is a very effective "truth test" for any Mass Air Flow Sensor. Start the engine, let it idle, and then check the Barometric Pressure reading on the scan tool data. If the reading is about 26.5 Hg and you are close to sea level, you know that you have a defective Air Flow Meter because it is telling you that you are at about 4500 feet above sea level. (These conversion tables will help.) The Barometric Pressure Sensor is part of the Mass Air Flow Sensor and will cause the Mass Air Flow Sensor to send incorrect data to the engine control module.
  • Sometimes the Air Flow Sensor and the sensing wire get covered with dirt, dust, or oil residue, which can also set a P0101. Cleaning the sensor might hold off problems for a while, but eventually, the MAF sensor should be replaced. Always make sure the Air Filter and its enclosure are dirt-, dust-, and oil-free. If you clean and replace the filter and its enclosure as needed, you will prevent the new MAF from failing.
 

JetJock

CCCUK Member
Ah, we clashed.
Yes, I've disconnected the battery while working away from home for 3 weeks.
And, I think you're saying that if a component is available, but not complete, then it fails a test. But, I wonder how this is rectified?

BTW, I'm pretty sure in the UK we only test with a probe in the exhaust, so I don't think this is an issue for testing.
 

teamzr1

Supporting vendor
I suggest

1. since you or someone was working in the engine bay, they may have caused an unmetered air leak
I would check from the MAF to the throttlebody for a loose air coupler or clamp
ANY leak like this can confuse what the MAF reports to the PCM and what it calculates as total airmass

2. The MAF internally is dirty, MUST use a MAF electronic cleaner ONLY
3. The MAF wiring connector is not firmly connected to MAF connector
4. one of the wiring connector male pins has a faulty crimp to wire
5. Use same cleaner and clean male and female pins

Also notice in those results shows at the time DTC tripped a "freeze" frame tripped
that is at the moment error occurred then freeze-frame is generated and as can be seen
your engine was running about 8% too lean for both B1 (left head) and B2 (right head)
and was LONG term fuel trim adjustments.
Positive fuel trims is lean, negative values means rich
 

JetJock

CCCUK Member
I'm going away now for a period of work, but I'll plan to look back at this issue on my return.
Thank you very much for your input, JR.
 

teamzr1

Supporting vendor
Ah, we clashed.
Yes, I've disconnected the battery while working away from home for 3 weeks.
And, I think you're saying that if a component is available, but not complete, then it fails a test. But, I wonder how this is rectified?

BTW, I'm pretty sure in the UK we only test with a probe in the exhaust, so I don't think this is an issue for testing.

I am surprised they just do not do as in the USA and just plug a OBD-II scanner, and it gives those on-board test results

Any time on-board smog tests are flushed out, the vehicle needs a drivecyle or enough drives for those tests to get
in a complete state

Always to prevent loss of on-board smog tests is use a battery tender and do not disconnect battery as it could take
multi drive cycles to get all tests back to complete state ( as long as those functions are working well)
 

teamzr1

Supporting vendor
See, I told you I was rubbish with IT - I've obviously messed it up and introduced all sorts of errors into the readout...
I assume the speed recorded (when it's correct, unlike this one) is the speed at which the warning first appears? :)
Can you please explain what this means?
View attachment 16221

Sorry, you need to expand ?
On what you're asking, as everything you see in the OBD-II report is what the controllers reported
 

JetJock

CCCUK Member
OK, thanks for that info about the smog tests. I don't know if they do that or not, with the OBD. I'll try to find out.

Sorry, you need to expand ?
On what you're asking, as everything you see in the OBD-II report is what the controllers reported

JR

I was suggesting I'd introduced an error into the speed recording...

But one final question, if you don't mind, before I go away:
If this issue doesn't return, is it possible it was just a transient environmental hiccup caused by an outside factor (going across a bridge?) or is it possible it's simply a computer glitch?
I'm already getting used to various random captions and warnings appearing (Tyre pressures showing 0, CHECK GAS CAP, etc) which seem to flag up then go away of their own accord or after a power reset.
Just like the Bombardier Challenger 350s I fly, in fact. We're forever getting weird BIT results or random captions that clear after a reset on those aircraft...
Even have to shut down both engines and pull the battery connectors sometimes, in order to clear these faults. Not in the air, obviously! :)

HOw do you do that quote thing with the red line down the left side?
 

teamzr1

Supporting vendor
OK, thanks for that info about the smog tests. I don't know if they do that or not, with the OBD. I'll try to find out.

Sorry, you need to expand ?
On what you're asking, as everything you see in the OBD-II report is what the controllers reported

JR

I was suggesting I'd introduced an error into the speed recording...

But one final question, if you don't mind, before I go away:
If this issue doesn't return, is it possible it was just a transient environmental hiccup caused by an outside factor (going across a bridge?) or is it possible it's simply a computer glitch?
I'm already getting used to various random captions and warnings appearing (Tyre pressures showing 0, CHECK GAS CAP, etc) which seem to flag up then go away of their own accord or after a power reset.
Just like the Bombardier Challenger 350s I fly, in fact. We're forever getting weird BIT results or random captions that clear after a reset on those aircraft...
Even have to shut down both engines and pull the battery connectors sometimes, in order to clear these faults. Not in the air, obviously! :)

HOw do you do that quote thing with the red line down the left side?

Just so you know,
Each DTC has a set of rules when PCM would trip a CEL
In this case, I am showing you for a 2005 C6 in the PCM calibration when the MIL is to be triggered ON
As you see for a P0101, it is set NOT to trip the MIL until the problem is seen for the second time,

This means the first time the MAF issue was tripped, that is when the freeze-frame was generated but the PCM stores that P0101
in memory but does not trip the MIL on the dash
IF the P0101 trips a second time, could be even a different drive, only then would PCM command MIL ON
COPs and courts have used OBD to wack people as to traffic tickets or crashes, so the values should be bulletproof.

Thus, could be someone else drive the car when hitting 118 MPH or maybe a repair shop going on a joy ride ?

That speed is backed up as you notice the gas pedal (TPS) was 88% (almost to the floor) and engine RPMS over 5,400
so was not some slow speed cruise speed.

Sure if there is some random issue like a loose ground, maybe a bad crimp to a connector pin, or slight airleak could cause a DTC
to trip,
Let DTCs age out on their own, do not flush or remove battery and then see if P0101 comes back on or not

Do NOT do flushes as again all smog tests are also then back to a failed state (non-complete)
Check for loose grounds like back of left head is a main ground off engine to frame,
loose ground on frame from battery or there are ground splice packs off of frame could be loose or a weak crimp to a wire pin

p0101jj.jpg
 

teamzr1

Supporting vendor
What you need what to learn now is how to start your scanner in "record" mode and what PIDs ( parameters) to have it record while you drive
I can show you how to set up a PID group so that when you drive the scanner only records the values of those PIDs which then get saved
into a recording file
Either later can replay that recording while not in the car or even send the recording to me and I can deep dive analyze all that data and see if
anything odd related to the MAF

Give you all a quiz later on :)
 

JetJock

CCCUK Member
Thanks again.
I'll revisit this in a few weeks. Recording sounds worthwhile for analysis, I imagine.
Wish you a good evening.
 
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