New Age Training Solutions - NATS

The problem with AI.
We have all used AI in some form. ChatGPT, Claude, Gemini, or any of the countless other systems appearing daily.
The issue is that most AI systems are designed to be agreement machines.
They are programmed to be highly helpful, polite, and conversational. That means they often mirror your assumptions instead of challenging them. In many cases, AI becomes more of a cheerleader than a critical thinking partner.
That works fine for black-and-white questions.
But diagnostics, troubleshooting, leadership, and real-world decision making are rarely ever black and white.
They involve variables, missing context, incomplete testing, human assumptions, and unknown failures.
AI cannot magically know a variable that was never tested or provided.
That is where people begin calling AI “useless.”
But the real issue usually is not the AI itself, it is HOW the AI is being used.
If the input is incomplete, biased, or assumption-based, the output often will be too.
To put this into perspective for the trades industry, the AI “prompt” is best compared to a calibration.
Just like any other tool, AI is only useful when calibrated correctly.
With the right prompts, structure, and logic flow, AI can absolutely help perform the job effectively.
The problem is that many AI systems are calibrated to agree with you instead of guiding you through critical thinking.
That creates guessing, assumptions, and confirmation bias.
In diagnostics, that can send you down the wrong path fast.
So we designed a system calibrated specifically for next-step diagnostics.
Instead of acting like an agreement machine, it guides the process toward a valid conclusion based on the real-time inputs that YOU provide.
There is no random guessing, no blind agreement, and no unsupported assumptions.
The goal was to create a tool that feels like a master technician standing beside you, looking at the repair with you, and helping guide the next logical step.
Not just helping you find an answer — helping teach you HOW to find the answer.
Because real diagnostics should challenge assumptions, verify inputs, and guide the next logical step based on evidence — not simply agree with the first theory presented.
AI should not replace critical thinking.
It should strengthen it.
That is the difference between an agreement machine…
and a true diagnostic tool.
Check out diagcoach.com today and try it free.

A lot of people in the skilled trades say:
“AI will never replace us.”

And honestly?
We hope they’re right.

But maybe the better question is:
Why would we WANT the trades to be AI proof?

This industry is facing massive technician shortages, increasingly complex systems, shrinking training pipelines, and diagnostic procedures that now require interpreting data streams, software logic, network communication, and advanced electronics.

We don’t need AI to replace technicians.

We need AI to HELP technicians.

Good AI should:
• Reduce wasted diagnostic time
• Help newer techs think more logically
• Speed up information access
• Assist with troubleshooting strategy
• Improve consistency
• Help shops train faster
• Reduce misdiagnosis and unnecessary parts replacement

The modern technician still needs to verify.
Still needs to test.
Still needs to understand systems.
Still needs hands-on ability.

AI cannot feel a slipping clutch.
It cannot smell burnt wiring.
It cannot hear a failing bearing over the noise of a shop.
It cannot replace experience.

But it CAN become another tool in the toolbox.

And if we ignore the tools being developed around us simply because we fear change, someone else will use them better and faster than we do.

The trades have always evolved.

Carburetors became fuel injection.
Points became computer-controlled ignition.
Paper diagrams became scan tools and digital diagnostics.

AI is simply the next evolution of information assistance.

The future probably isn’t:
“Technicians vs AI.”

It’s likely:
“Technicians using AI vs technicians who don’t.”

And the shops, fleets, and technicians who learn how to use these tools correctly will probably have a major advantage moving forward.

The goal should never be replacing skilled people.

The goal should be making skilled people even more capable.

www.diagcoach.com

Understanding Fuel Trims

Understanding fuel trims is far more valuable than simply memorizing:
“Positive adds fuel, negative removes fuel.”

Fuel trims tell a story about what is happening with an engine. To read that story, we have to understand the language.

So what are we actually seeing when we look at fuel trim numbers? A percentage? A volume measurement?

Not exactly.

What we are really seeing is the PCM moving within a preset fuel strategy map to achieve the air/fuel ratio it wants.

The ultimate goal in a gasoline engine is stoichiometry.

That means approximately 14.7 parts air to 1 part fuel. This is considered the ideal mixture for efficient combustion, power, and low emissions.

The PCM monitors the oxygen sensors to help determine whether the combustion event was rich or lean based on the exhaust leaving the cylinders.

Inside the PCM are preset fuel strategies and correction limits programmed by the manufacturer.

For example, if an engine is running lean, the oxygen sensor reports more oxygen in the exhaust stream than the PCM expected to see.

The PCM first reacts using short term fuel trims, which move very quickly.

If the condition continues over time, the PCM begins shifting long term fuel trims toward enrichment to compensate.

The PCM then continues monitoring oxygen sensor feedback and short term fuel trims to see if the correction was enough.

If not, it continues adjusting fuel strategy until it either achieves stoichiometry or reaches its programmed correction limits.

Most systems typically max out somewhere in the high 20% to low 30% range depending on the manufacturer.

Ideally at idle, fuel trims should remain relatively close to zero.

That would indicate the engine is operating efficiently and the PCM does not need to make major corrections.

In the real world, though, fuel trims almost never stay perfectly at zero. Small adjustments are completely normal.

Generally speaking, short term fuel trims within about positive or negative 10% and long term trims close to zero are usually considered acceptable in many situations.

One of the easiest ways to think about fuel trims is this:

**Short Term Fuel Trim = what the PCM is seeing right now**
**Long Term Fuel Trim = what the PCM has learned and is doing to correct**

Short term moves fast and reflects what the PCM is reacting to in that exact moment.

Long term moves slower and helps tell the larger story about what the PCM has been correcting over time.

If the PCM sees a condition continue long enough, it starts building that correction into long term fuel trims.

This is where things become very useful diagnostically.

Example:

Let’s say you can feel a misfire, but there are no codes stored.

If we look at fuel trims, we may be able to identify several things.

First, on a V6 or V8 engine, we may be able to determine which bank is affected.

Second, we may be able to determine whether the PCM is reacting to a rich or lean condition based on the trim numbers.

If the issue is related to spark, unburned fuel may enter the exhaust stream and affect oxygen sensor readings. In many cases, this can cause long term fuel trims to move negative over time as the PCM attempts to compensate.

If the issue is caused by something like a vacuum leak, we would typically expect the opposite reaction.

Fuel trims are not just numbers.

They tell a story about what the computer has been seeing over time versus what it is reacting to right now.

Good diagnostics comes from understanding why the PCM is making the correction.

AI Diagnostic Assistant for Technicians | NATS Diag Coach NATS Diag Coach helps technicians troubleshoot vehicle problems using AI-guided diagnostic assistance, real-world input, step-by-step workflow support, and process-based troubleshooting.

Commanded vs. Actual: A Diagnostic Tip

Modern vehicles are computer-controlled to balance performance, efficiency, and emissions.

The PCM makes decisions based on inputs like engine load, throttle position, temperature, airflow, and other sensor data. From there, it commands an output.

But here’s the key:

The computer will not command something the system is not mechanically capable of delivering.

If, by design, a fuel system is only capable of producing 70 PSI, the PCM is not ever going to command 80 PSI.

That is why commanded vs. actual data is so powerful diagnostically.

If the PCM is commanding a certain fuel pressure, duty cycle, actuator position, boost level, EGR flow, fan speed, or any other parameter you are looking at — and the actual result does not match — that gives us direction.

Example:

If commanded fuel pressure is higher than actual fuel pressure, we now know the system is not delivering what the PCM is asking for.

That does not automatically mean its a bad fuel pump.

It means we verified a symptom and we need to test further.

Possible causes could include:

• Fuel pump circuit resistance
• Restricted fuel filter
• Weak fuel pump
• Low fuel level
• Air being pulled into the system
• Fuel pressure regulator issue
• Wiring or ground issue
• Mechanical restriction

This is where good diagnostics matters.

A voltage drop test at the pump circuit can quickly help determine whether we are dealing with an electrical issue or a mechanical fuel delivery issue.

Many bidirectional scan tools can also help us test these systems by manually commanding components on or changing commanded values while monitoring the actual response.

If we command higher fuel pump duty cycle and actual fuel pressure still does not respond correctly, we know the issue is not simply a PCM command issue.

The same logic applies far beyond fuel pressure.

Commanded vs. actual can help diagnose:

• Turbo boost / VGT issues
• EGR flow problems
• Cooling fan concerns
• Electronic throttle operation
• Cam/crank timing / VVT issues
• DEF dosing problems
• HVAC door operation
• Transmission pressure control issues

Even when there are no useful fault codes, commanded vs. actual data can still help build a diagnostic path.

This is why experienced technicians always review scan tool live data — not just codes.

Codes are a starting point, not an answer.

Data tells the story.

Testing proves the answer.

Check out www.diagcoach.com today.

AI Diagnostic Assistant for Technicians | NATS Diag Coach NATS Diag Coach helps technicians troubleshoot vehicle problems using AI-guided diagnostic assistance, real-world input, step-by-step workflow support, and process-based troubleshooting.

The resistance to AI is definitely understandable. We have all seen feedback like this:

Tech:
“I think it’s the fuel pump.”

AI:
“Likely fuel pump.”

Tech:
“Fuel pressure is actually perfect.”

AI:
“Then likely injectors.”

Tech:
“Injector pulse is missing.”

AI:
“Then likely crank sensor.”

Tech:
“RPM PID works.”

AI:
“Then maybe PCM.”

That’s not diagnostics.

That’s an agreement machine throwing guesses at the wall.

Real diagnostics should challenge assumptions, verify inputs, and guide the next logical step based on actual evidence.

AI is a tool — just like any other tool in your toolbox. When used incorrectly, it can be pretty useless. It has to be used correctly and HELP YOU find the root problem.

Good AI should improve the diagnostic process — not amplify guessing.

Diag Coach wasn’t built to simply agree with you or throw random answers at the wall. It was designed to help guide the next logical diagnostic step using your real-world input in real time to help you find the RIGHT answer.

Because making better technicians helps both the shop AND the customer.

Built by Technicians. Verified by AI.

Try it free at

AI Diagnostic Assistant for Technicians | NATS Diag Coach NATS Diag Coach helps technicians troubleshoot vehicle problems using AI-guided diagnostic assistance, real-world input, step-by-step workflow support, and process-based troubleshooting.