Engine Maintenance: OBD II Diagnostics, Misfire Codes, Fuel Trim Faults, Driveability and More – UnderhoodService

Engine Maintenance: OBD II Diagnostics, Misfire Codes, Fuel Trim Faults, Driveability and More

As automotive electronics diagnostics continues to evolve, so do the tools that are need to diagnose and repair today's complex engine and electronics systems. This lineup will arm you will some diagnostic tips and give you some invaluable service advantages on Porsche, BMW, Hyundai and Mazda models.

Tech Tip: Hyundai Check Engine Light Diagnostics

There are a couple of ways a Hyundai will find its way into your bay with a check engine light complaint. If a misfire is obvious, you may be tempted to get to work and start switching coils, checking wires or whatever, looking to diagnose the problem. But before you do, check the codes to see if more… More
Porsche Engine Diagnostics: Misfire Codes, Fuel Trim Faults, Secondary Air Injection

Porsche has been building engines for decades that will literally fit in a suitcase, but are still able to put out horsepower that rivals many larger engines. Find out how to keep the Porsche Boxster engine running smoothly. More
 
Tech Feature: Mazda Driveability Diagnostics and Check Engine Light Complaints

From a torn air intake hose to ignition system concerns, Bob Dowie tackles driveability issues as well as some of the more common ailments that will bring Mazda vehicles into your bays with a check engine lamp complaint. More
   
BMW Climate Control Diagnostics: Resolving Any Cooling System Problems First Speeds Repairs

First Speeds Repairs There was a time when the heating and ventilation system on most cars was simple. A three-position switch, a couple of levers and maybe some separate vents that would allow outside air to enter the pass More
Tech Feature: Fueling the Future – Can You Fill Up with Alternative Fuels?

Currently gas prices have stabilized at around $1.83 a gallon, a price at which most Americans feel comfortable driving their SUVs, trucks, race cars, tow vehicles and other motorized toys. But when gas hits $4 and $5 a gallon, driving guzzlers becomes a challenge for many. It was only a few months ago… More
Tech Tip: OBD II Engine Diagnostics

Anybody can plug a scan tool into a vehicle and read codes. But do they know what the codes mean, how to diagnose the fault or, most importantly, how to fix the vehicle? The problem with reading OBD II codes is that the code tells you only that a fault has occurred. It does not tell you why the fault… More
Tech Tip: Belt and Hose Inspections

Although belts and hoses are still classified as expendable parts, their durability has increased to the point that many import shop owners and technicians are now neglecting to perform routine belt and hose inspections. From a historical perspective, belts and hoses have moved from a recommended replacement… More

OBD II Engine Diagnostics: Not as Simple as it Seems

Anybody can plug a scan tool into a vehicle and read codes. But do they know what the codes mean, how to diagnose the fault or, most importantly, how to fix the vehicle? The problem with reading OBD II codes is that the code tells you only that a fault has occurred. It does not tell you why the fault… More

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It’s Got Spark!

Why can’t you trust some spark tests?

You have probably seen some reality TV shows where the “builder” will pull a spark plug wire to confirm they have spark. This is one of the most misleading tests for the ignition system. If the spark plug produces a spark, the spark is at 14.6 psi (normal air pressure at sea level), not 170 psi or more inside the cylinder during the top of the power stroke.

Why Alternators Are Subject To Ripple Voltage

The alternator produces an AC current that must be converted into DC current by way of a rectifier.

ECM Damage

Engineers have devised two strategies that can be called the “immune system” for the electrical system.

Voltage Drop Testing

The measurement of voltage is like the speed of the traffic.

Spark Plug Fouling

Understanding why spark plugs get dirty.

Other Posts

Forcing OBD II Vehicle Emission Monitors

Some vehicles have readiness issues when it comes to setting all the OBD II monitors.

Auxiliary Water Pump Diagnostics

A car or truck comes into your shop with a complaint of poor heater performance- the issue may be the auxiliary water pump.

Hybrid Vehicle Fluid Maintenance

There are opportunities your shop can’t pass up just because the car or SUV has a hybrid badge on the back.

Ignition Coil Output

To see inductance inside the primary windings, use an amp probe placed around the positive wire for the ignition coil.