Tech Feature: Diagnosing Intermittent Driveability Issues
Intermittent driveability problems of any kind are always a challenge to diagnose. When a customer brings you a vehicle and complains of a stalling problem, you may not have much to go on other than their description of what is happening and when it happens. The more information you can get out of them the better, because you’ll likely need all the details you can get to narrow down the list of possible causes. Many times, there will be no check engine light ….
Diagnostic Dilemmas: Down to the Wire
Five years ago, I began seeing a very small number of General Motors products come through the door with a variety of trouble codes indicating a “circuit failure” in the intake air temperature (IAT) sensors, mass air flow (MAF) sensors, throttle position (TP) sensors and idle air control (IAC) systems. In all cases, these failures
COP Connection: Investigating Common Coil-on Plug Misfires
For a number of reasons, the trend of modern engine management technology is leaning toward using coil-on-plug (COP) ignition systems. One reason is that COP ignitions are very compact and are very adaptable to individual cylinder tuning. With the exception of a few designs that incorporate a driver or “module” into the COP assembly itself,
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 occurred, what might be causing the problem, or what needs to be repaired or replaced ….
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
Diagnosing Intermittent Stalling Issues
Intermittent driveability problems of any kind are always a challenge to diagnose. When a customer brings you a vehicle and complains of a stalling problem, you may not have much to go on other than their description of what’s happening and when it happens. The more information you can get out of them the better,
Tech Tip: Diagnosing Intermittent Stalling Issues
Intermittent driveability problems of any kind are always a challenge to diagnose. When a customer brings you a vehicle and complains of a stalling problem, you may not have much to go on other than their description of what is happening and when it happens. The more information you can get out of them the better, because you’ll likely need all the details you can get to narrow down the list of possible causes ….
Tech Tip: Misfires May Cause Engine to Feel Rough, Lack Power and Use More Gas
When you have a misfire code for a particular cylinder, you can focus on one of three things: an ignition problem, a fuel injector problem or a compression problem. Ignition problems that can cause misfires include worn or fouled spark plugs, bad plug wires, moisture on the plugs or plug wires, or a weak or dead ignition coil ….
Tech Tip: Larry Carley Covers the Top 10 Domestic Diagnostic Codes and Fixes
Some people think a code is all you need to fix a fault and turn off the Check Engine Light (or Malfunction Indicator Lamp or MIL). A diagnostic trouble code (DTC) certainly helps, but it only tells you that some kind of fault has occurred, and maybe the circuit or component associated with the fault. But no code by itself can tell you which part to replace, because in many instances any one of several causes may have set the code ….
Mazda Tech Tip: Curing Rough Idle During or Immediately After a Cold Start
Automotive fuel with high alcohol content may damage the fuel pressure regulator diaphragm. The damage to the diaphragm may allow fuel to enter the vacuum supply line for the fuel pressure regulator. The vacuum supply line uses the No. 3 intake runner as the vacuum source. The unmetered fuel entering the No. 3 cylinder on cold starts may cause a rich mixture misfire.