Intermittent no-code issues on 2022.5+ V8 trucks — what did the shop fail to capture?

[bluev8]

New member here. I am researching a read-first event-recorder concept for late-model GM V8 trucks.

This is not a sales post. There is no product link, price, preorder, or mailing list. I am trying to determine whether the underlying problem is real before building anything.

 

Has your truck ever had a brief problem such as:

- rough running or a momentary misfire
- an oil-pressure warning or unusual pressure event
- reduced power or a brief stall
- a U-code or lost-communication problem
- a symptom that disappeared before the dealer or independent shop could reproduce it

 

If so, I would appreciate the following details:

- year, model, engine, and mileage
- what happened and under what conditions
- whether a DTC and useful freeze-frame data were stored
- whether the shop was able to reproduce it
- what the eventual confirmed repair was, if known
- what additional information would have helped the diagnosis

 

The concept being evaluated is a removable leave-in recorder that continuously retains a rolling window from before and after an event. It would not tune, reflash, clear codes, or change the vehicle calibration.

 

I am also not claiming that it could predict lifter failure or see every internal ECM variable.

 

The real question is whether continuous event history would add enough useful evidence beyond freeze frame, GDS2, and existing scan tools — or whether it would simply be another unnecessary gadget.

 

For owners and technicians, which problem would make something like this genuinely useful:

1. intermittent misfire or AFM/DFM-related behavior
2. oil-pressure events
3. lost communication or electrical faults
4. none of the above

Please be blunt. Negative feedback is just as useful as positive feedback.

[asilverblazer]

Length/amount of data capture will be important to consider, sifting through 5 minutes of a data log can be enormous when it is stored in milliseconds. Being able to find the 'event' let alone decipher it.

 

Presumably the driver would notice something and hit a button to capture the 'window' of data. That window has to be large enough for the operator to recognize the event and react accordingly. 

 

The data has to be able to be retrieved easily.

 

The data has to be able to be understood. Which is the biggest challenge, dealer techs won't even know what most of it is and would likely not even look at it if an owner brought it to them. Meaning the owner, the least educated/qualified, trying to understand it. 

 

How will the data be presented? Could specific PIDs be selected and a timelapse graph be watched? How will a specific value be noted as abnormal? Additionally, a good data logger would be able to 'learn' normal values for a specific vehicle and flag abnormalities automatically. It could in theory watch parameters degrade over time and suggest maintenance as needed. (If the MAF reading begins tapering off for a given set of other readings - MAP, throttle position, Ambient, etc.. a flag to check air filter.) With the amount of data available, a device (really the vehicle rather than an additional accessory) should be able to do more than issue a DTC. It should be able to run the full diagnostic suite automatically and present a solution rather than a code. (It's not the 90's anymore). The technology is available for the vehicle to not just say "P0087", it should know low fuel pressure, check other PIDs to narrow down the problem itself, and determine if it is a lift pump, high pressure pump, regulator, leak in the fuel line, clogged filter, etc. Even if it can't narrow it down, it should be able to guide the user to the likely problems.

 

This would be a major problem for dealer service departments, which are the manufacturers customers it is in their collective best interest to NOT have this available to the consumer.

 

Further, if the owner is going to be the primary consumer of the data, it's got to be at a consumer price point vs. dealer only specialty tool price.

 

This group is more 'involved' in their vehicle than general public/consumer and will have knowledge, experience, needs and desires that are quite different from the market at large. 

 

[bluev8]

2 hours ago, asilverblazer said:

Length/amount of data capture will be important to consider, sifting through 5 minutes of a data log can be enormous when it is stored in milliseconds. Being able to find the 'event' let alone decipher it.

 

Presumably the driver would notice something and hit a button to capture the 'window' of data. That window has to be large enough for the operator to recognize the event and react accordingly. 

 

The data has to be able to be retrieved easily.

 

The data has to be able to be understood. Which is the biggest challenge, dealer techs won't even know what most of it is and would likely not even look at it if an owner brought it to them. Meaning the owner, the least educated/qualified, trying to understand it. 

 

How will the data be presented? Could specific PIDs be selected and a timelapse graph be watched? How will a specific value be noted as abnormal? Additionally, a good data logger would be able to 'learn' normal values for a specific vehicle and flag abnormalities automatically. It could in theory watch parameters degrade over time and suggest maintenance as needed. (If the MAF reading begins tapering off for a given set of other readings - MAP, throttle position, Ambient, etc.. a flag to check air filter.) With the amount of data available, a device (really the vehicle rather than an additional accessory) should be able to do more than issue a DTC. It should be able to run the full diagnostic suite automatically and present a solution rather than a code. (It's not the 90's anymore). The technology is available for the vehicle to not just say "P0087", it should know low fuel pressure, check other PIDs to narrow down the problem itself, and determine if it is a lift pump, high pressure pump, regulator, leak in the fuel line, clogged filter, etc. Even if it can't narrow it down, it should be able to guide the user to the likely problems.

 

This would be a major problem for dealer service departments, which are the manufacturers customers it is in their collective best interest to NOT have this available to the consumer.

 

Further, if the owner is going to be the primary consumer of the data, it's got to be at a consumer price point vs. dealer only specialty tool price.

 

This group is more 'involved' in their vehicle than general public/consumer and will have knowledge, experience, needs and desires that are quite different from the market at large. 

 

That makes sense, and I think you are describing the real product problem.

Capturing data is the easy part. If the owner or technician has to manually dig through five minutes of millisecond-level logs, the product has already failed.

The device would be at the ECM harness, not at the OBD port, so I agree that data retrieval and event marking need to be thought through carefully.

The way I am thinking about the architecture is:

1. The recorder itself should not depend on a phone, app, Bluetooth, Wi-Fi, or cloud connection to capture the event. It should always keep a local rolling buffer and lock the event locally.

2. A button, phone app, or small cabin device would only act as an event marker. If the driver feels a stumble and presses the button 10–30 seconds later, the pre-buffer has to already contain the useful data.

3. For data retrieval, the practical options would be a sealed service USB lead, Wi-Fi download, or a phone/cabin companion device. I would not expect the owner to remove the ECM-side module or work with raw files directly.

4. The cloud or AI side would be for interpretation, not for capturing the event. The truck may have no connection when the issue happens, so the evidence has to be saved locally first. After that, cloud processing could help decode the data, compare it against baselines, and generate a readable report.

For the first version, I would keep the automatic triggers conservative and objective:

• driver event marker

• bus-off

• error passive

• voltage drop / brownout

• device reset

• FIFO or queue overflow

• a normally periodic message disappearing

• side-to-side communication mismatch, if the topology supports that

For “learning normal,” I agree with your point, but I would not want to overclaim it as automatic root-cause diagnosis at first.

A realistic first step would be learned baseline comparison for that specific vehicle and operating condition. For example, a value would only be compared against similar conditions:

• RPM range

• load / MAP

• throttle position

• gear / vehicle speed

• coolant and oil temperature

• battery voltage

• AFM/DFM state, if decoded and validated

Then the report could flag things like:

• this periodic message disappeared compared with its normal timing

• this value deviated from this vehicle’s normal range under similar conditions

• the same abnormal pattern repeated after the same type of event

• the anomaly occurred together with voltage, oil-pressure, misfire, or communication changes

But I would still call that “abnormal pattern detected,” not “replace this part,” unless there is enough validated repair data behind it.

So the intended product would not be “here is a huge log.” It would need to be an event package:

• what triggered the capture

• how much pre/post data was preserved

• what changed before and after the event

• whether the device itself reset, overflowed, or saw a bus error

• selected graphs around the event

• raw data only as supporting evidence

From your perspective, what would make this kind of report useful instead of just another datalog?

For example:

1. What are the top 5 parameters or events you would want highlighted first?

2. Would you trust a learned baseline for that specific vehicle, or would you prefer fixed thresholds?

3. How much false-positive flagging would be acceptable before you stopped looking at the reports?

4. What would a one-page report need to show for an independent shop to take it seriously?

5. For misfire, AFM/DFM, oil pressure, or U-code complaints, what would you want the tool to flag automatically?

[asilverblazer]

7 hours ago, bluev8 said:

That makes sense, and I think you are describing the real product problem.

Capturing data is the easy part. If the owner or technician has to manually dig through five minutes of millisecond-level logs, the product has already failed.

The device would be at the ECM harness, not at the OBD port, so I agree that data retrieval and event marking need to be thought through carefully.

The way I am thinking about the architecture is:

1. The recorder itself should not depend on a phone, app, Bluetooth, Wi-Fi, or cloud connection to capture the event. It should always keep a local rolling buffer and lock the event locally.

2. A button, phone app, or small cabin device would only act as an event marker. If the driver feels a stumble and presses the button 10–30 seconds later, the pre-buffer has to already contain the useful data.

3. For data retrieval, the practical options would be a sealed service USB lead, Wi-Fi download, or a phone/cabin companion device. I would not expect the owner to remove For “learning normal,” I agree with your point, but I would not want to overclaim it as automatic root-cause diagnosis at first.

A realistic first step would be learned baseline comparison for that specific vehicle and operating condition. For example, a value would only be compared against similar conditions:

• RPM range

• load / MAP

• throttle position

• gear / vehicle speed

• coolant and oil temperature

• battery voltage

• AFM/DFM state, if decoded and validated

Then the report could flag things like:

• this periodic message disappeared compared with its normal timing

• this value deviated from this vehicle’s normal range under similar conditions

• the same abnormal pattern repeated after the same type of event

• the anomaly occurred together with voltage, oil-pressure, misfire, or communication changes

But I would still call that “abnormal pattern detected,” not “replace this part,” unless there is enough validated repair data behind it.

So the intended product would not be “here is a huge log.” It would need to be an event package:

• what triggered the capture

• how much pre/post data was preserved

• what changed before and after the event

• whether the device itself reset, overflowed, or saw a bus error

• selected graphs around the event

• raw data only as supporting evidence

From your perspective, what would make this kind of report useful instead of just another datalog?

For example:

1. What are the top 5 parameters or events you would want highlighted first?

2. Would you trust a learned baseline for that specific vehicle, or would you prefer fixed thresholds?

3. How much false-positive flagging would be acceptable before you stopped looking at the reports?

4. What would a one-page report need to show for an independent shop to take it seriously?

5. For misfire, AFM/DFM, oil pressure, or U-code complaints, what would you want the tool to flag automatically?

I think users are going to want to pick their monitored parameters, which parameters they want to see first. 
 

It should probably start with baseline at a minimum and adjust to learned, but be able to overlay baseline for comparison.
 

A simple severity level would be able to determine what type of alerting is appropriate or user selectable. 
 

Why not use the OBD port though?

 

I think a phone connection would be a good idea, push notifications type deal.

 

Number 1 issue is having data is useless if you don’t know what the data should be under normal conditions. 

[davester]

There's also a LOT of data of log, as there are a whole bunch of computers in the truck.  The more you log, the less often you can sample it (as the computers and busses are busy running the truck, logging gets whatever is left over.

[bluev8]

12 hours ago, asilverblazer said:

I think users are going to want to pick their monitored parameters, which parameters they want to see first. 
 

It should probably start with baseline at a minimum and adjust to learned, but be able to overlay baseline for comparison.
 

A simple severity level would be able to determine what type of alerting is appropriate or user selectable. 
 

Why not use the OBD port though?

 

I think a phone connection would be a good idea, push notifications type deal.

 

Number 1 issue is having data is useless if you don’t know what the data should be under normal conditions. 

That makes sense, and I agree with most of that.

 

I think the product would need both:

1. a default powertrain template, so it is useful out of the box;
2. user-selected priority parameters, so the owner or shop can choose what they want to see first.

 

Different users are going to care about different things. One owner may care about oil pressure and voltage. Another may care about misfire trend, AFM/DFM behavior, or U-codes. A shop may want communication events and repeatability first.

Your baseline point is probably the most important one. Raw data is not very useful unless the report can show what normal looked like for that vehicle under similar conditions.

 

The way I would think about it is:

- start with a basic known-good baseline
- learn normal behavior for that specific vehicle over time
- allow the event to be overlaid against baseline
- show whether the event was a one-time spike or a repeatable pattern
- provide a simple severity level, but with clear limits on what that severity means

 

For example, early severity could be something like:

- Info: event captured, no obvious abnormal pattern
- Watch: value moved outside baseline, but not repeated
- Warning: repeatable abnormal pattern under similar conditions
- Critical: communication loss, voltage drop, bus-off, reset, or severe repeated event

 

I would not want the first version to say “replace this part.” That would be overclaiming unless there is repair-confirmed data behind it. It would be more honest to say “this pattern deserves inspection.”

 

On the OBD port question, I think OBD absolutely has a role.

OBD is probably the right place for:

- DTCs
- freeze frame
- VIN
- calibration information
- normal scan-tool parameters
- Mode 6 / enhanced diagnostic data if available

The reason I am still looking at an ECM-side recorder is that the failure may happen before anyone connects a scan tool. If the owner plugs in a scanner after the event, the pre-event evidence may already be gone unless the ECU happened to save it.

So I do not see this as “OBD versus ECM-side.” I see it more like:

- ECM-side recorder: always armed, rolling buffer, event evidence
- OBD/DLC companion: DTCs, freeze frame, VIN, calibration, normal scan data
- phone/cloud: status, notes, upload, report generation, notifications

 

I agree that phone connection and push notifications would be useful. I just would not want the phone or cloud connection to be required for capture. The recorder should save the event locally even if the phone is not connected. The phone should help with event marking, download, notes, upload, alerts, and report viewing.

 

For a default GM V8 event report, would this list make sense?

- RPM
- calculated load / MAP
- throttle position
- vehicle speed
- gear / torque converter state if available
- coolant temperature
- oil pressure
- oil temperature if available
- battery voltage
- commanded AFM/DFM state if available
- actual AFM/DFM state if available
- misfire counters / roughness by cylinder if available
- fuel trims
- relevant U-codes / communication events
- bus-off / lost periodic message / module reset / voltage drop events

Which of those would you remove, and what would you add?

[bluev8]

9 hours ago, davester said:

There's also a LOT of data of log, as there are a whole bunch of computers in the truck.  The more you log, the less often you can sample it (as the computers and busses are busy running the truck, logging gets whatever is left over.

That is a fair point, and I agree that trying to log “everything in the truck” would be the wrong direction.

 

There are a lot of modules and a lot of traffic. If the product became a full-truck datalogger, the amount of data would get huge very quickly, and most owners would never use it.

 

I think the first useful version would need to be narrow:

- powertrain-side event evidence
- selected high-value parameters
- communication / voltage / reset events
- pre/post event window
- short report first, raw log only as backup

 

One distinction I should make is between active OBD/PID polling and passive bus capture.

If you are polling PIDs through OBD, then yes: the more parameters you request, the lower the effective sample rate becomes, and you are adding diagnostic traffic to a vehicle that is already busy running itself.

With passive CAN capture, the recorder is not asking all the modules for data. It is listening to traffic that is already on the bus. So it does not consume vehicle bus bandwidth in the same way that a scan tool polling hundreds of PIDs would.

But your point still applies in a different way.

 

Even if passive capture does not add bus traffic, the recorder still has limits:

- processing rate
- storage rate
- timestamp accuracy
- decoder workload
- event filtering
- report size
- user attention span

 

So the answer cannot be “log everything and let the user figure it out.”

The product would need to store enough raw evidence to be useful, but only decode, graph, and present the important parts around the event.

 

A practical report should probably show:

- what triggered the capture
- how much pre/post data was preserved
- which selected parameters changed
- how those values compared to baseline
- whether the same pattern happened before
- whether any voltage, reset, bus-off, lost-message, or communication fault occurred
- selected graphs around the event
- raw data only as supporting evidence

 

So I agree with you. More data is not automatically better. The real product is the reduction from raw data into a useful event report.

[davester]

passive listening likely misses a lot of useful data for any system probelms (vs bus/communication problems), which are more common.

and you would need to poll most everything, because you have no idea what/where the problem happens, and data from just prior to the event is likely more important than what's happening after the event.

 

It would likely be more useful/successful, to be set to look at a specific subsystem, so after some random problem happens, then you attach this device, set to watch/log for that specific problem the next time it happens.

[asilverblazer]

On 6/27/2026 at 12:42 PM, bluev8 said:

I think the product would need both:

1. a default powertrain template, so it is useful out of the box;
2. user-selected priority parameters, so the owner or shop can choose what they want to see first.

Yes.

 

On 6/27/2026 at 12:42 PM, bluev8 said:

The way I would think about it is:

- start with a basic known-good baseline
- learn normal behavior for that specific vehicle over time
- allow the event to be overlaid against baseline
- show whether the event was a one-time spike or a repeatable pattern

Yes.

 

On 6/27/2026 at 12:42 PM, bluev8 said:

- provide a simple severity level, but with clear limits on what that severity means

 

For example, early severity could be something like:

- Info: event captured, no obvious abnormal pattern
- Watch: value moved outside baseline, but not repeated
- Warning: repeatable abnormal pattern under similar conditions
- Critical: communication loss, voltage drop, bus-off, reset, or severe repeated event

We might be intermingling ideas with the term 'severity', in one of my past vehicles it could pull up DTC via the vehicles own user interface, at any given time when one would do this there would be an assortment of codes that were 'trivial' including 'communication' issues. This would generate a bunch of, potentially false alerts or some many that they would get ignored. Which you mentioned earlier. 

 

You also mention several things that might be redundant with the vehicles own systems or indicators: The truck has an oil pressure gauge, monitoring it via this other system wouldn't be a priority except in comparison to other values or if there is an actual oil pressure problem.

 

Same thing for miss-fires or other problems, the MIL already signals the operator to an issue...

 

...to the point about what one wants to see first, if there is a miss fire detected, I want to see miss fire counts or fuel trims first, if I have an oil pressure problem I want to see the oil pressure first. So, perhaps the 'systems' that are showing abnormalities are what gets displayed first.

 

On 6/27/2026 at 12:42 PM, bluev8 said:

 

The reason I am still looking at an ECM-side recorder is that the failure may happen before anyone connects a scan tool. If the owner plugs in a scanner after the event, the pre-event evidence may already be gone unless the ECU happened to save it.

I think your device is what connects at the OBD port, ease of use for the consumer, it could still have a 'pass-through' port for a second scanner, computer, etc.

 

On 6/27/2026 at 12:42 PM, bluev8 said:

- phone/cloud: status, notes, upload, report generation, notifications

 

I agree that phone connection and push notifications would be useful. I just would not want the phone or cloud connection to be required for capture. The recorder should save the event locally even if the phone is not connected. The phone should help with event marking, download, notes, upload, alerts, and report viewing.

Yes.

 

On 6/27/2026 at 12:42 PM, bluev8 said:

For a default GM V8 event report, would this list make sense?

- RPM
- calculated load / MAP
- throttle position
- vehicle speed
- gear / torque converter state if available
- coolant temperature
- oil pressure
- oil temperature if available
- battery voltage
- commanded AFM/DFM state if available
- actual AFM/DFM state if available
- misfire counters / roughness by cylinder if available
- fuel trims
- relevant U-codes / communication events
- bus-off / lost periodic message / module reset / voltage drop events

Which of those would you remove, and what would you add?

Based on my comment above, if an error appears, the report would be more specific to the system having an error.

[asilverblazer]

On 6/27/2026 at 12:44 PM, bluev8 said:

So the answer cannot be “log everything and let the user figure it out.”

The product would need to store enough raw evidence to be useful, but only decode, graph, and present the important parts around the event.

 

A practical report should probably show:

- what triggered the capture
- how much pre/post data was preserved
- which selected parameters changed
- how those values compared to baseline
- whether the same pattern happened before
- whether any voltage, reset, bus-off, lost-message, or communication fault occurred
- selected graphs around the event
- raw data only as supporting evidence

 

So I agree with you. More data is not automatically better. The real product is the reduction from raw data into a useful event report.

Exactly.