AC Compressor Operation There are several different compressor designs, but all perform the same function: they move, or pump the refrigerant throughout the system, and they compress the low pressure vaporized refrigerant into a high pressure vapor. Compressors may be of a piston, rotary vane or scroll design. Piston style compressors are the most popular, and are either in line,… Read this article →

Limited slip differentials lock two wheels together while traveling in a straight line. While cornering it allows for the outside wheel to rotate faster than the inside by overcoming the tension of a clutch. The clutch type differential is the most common and consists of two sets of multiple disc clutch packs located on each of the two side gears.… Read this article →

The ignition system is designed to convert battery voltage into the high voltage required to ignite the air/fuel charge in the cylinders. There are two basic types of ignition systems as defined by SAE: Electronic Ignition (EI) and Distributor Ignition (DI). Although both types are electronic, SAE assigned the term ‘Electronic Ignition’ exclusively to distributorless designs. In contrast, Distributor Ignition… Read this article →

Electronic engine control systems have been standard equipment on most cars and light trucks since the early 1980s. While these systems improve both driveability and fuel economy, their primary purpose is emission control. From a service standpoint, many of the early systems were difficult to diagnose due to their limited self-diagnostic capability. However, serviceability improved in 1988 with the implementation… Read this article →

Learning the basics of the automotive starting and charging systems is good for both the service consultant standpoint and also just basic general knowledge for yourself. A lot of your customers will have these basic understandings so interpretation is not as important. Automotive systems operate on DC (Direct Current). The starting & charging system consists of the generator, voltage regulator,… Read this article →

A/C Performance Testing A performance test can determine whether the A/C system is functioning properly and if it is not can indicate what is wrong so the system can be repaired.Different vehicle manufacturers specify different methods to conduct system performance checks, but as a guideline, the following procedure may be used.Connect a manifold gauge set as previously described. Hang the… Read this article →

The link between vehicle emis­sions and air pollution was first identified by studies that began in California during the early 1940s. By the end of that decade, research­ers determined that the smog above California’s Los Angeles Basin was the result of hydrocarbon and oxides of nitrogen emissions from motor vehicles . As automobile manufactur­ers looked into isolating the source of… Read this article →

Heater Core Replacement SET-UP The pictures will be labeled in steps. To start out you will need an area to put everything. I usually put a blanket on the roof of the vehicle and place all removed parts in a stacking order. There will also be lots of clips, bolts and nuts. Some advice, have at least five separated containers… Read this article →

Accessing Bi-Directional Controls on the scan tool is much like Mode $06, it varies from scan tool to scan tool. Some scan tools will call them Output Controls, Bi-Directional Control, Test On Board System, Activate System, Service Bay Tests, Functional Tests or even Mode $08. In this article we will diagnosis a EVAP system fault using Bi-Directional Controls. So we… Read this article →

Inspection/Maintenance (IM) The advances made in engine management and emission control technology over the past two decades have resulted in the steady decline of vehicle pollutants. Unfortunately, while HC, CO and NOx output per vehicle is lower than ever before, emissions reductions have been offset by the extraordinary increase in the number of cars and trucks on the road. However,… Read this article →

99 Subaru Impreza: Clutch Replacement STEP 1: Start with the top side, this tutorial is for the Subaru Impreza 2.2l SOHC, if you happen to be working on the WRX turbo model the clutch configuration is different. There is a release pin for the clutch fork that has to be removed in order to remove the transmission. Anyways, disconnect the… Read this article →

This article will explain the Chrysler MDS and VCT system operation and components used on the new Hemi 5.7L V-8. Multiple Displacement Systems (MDS) is a system used on the 5.7L Chrysler Hemi V-8 engines to allow 4 cylinder operation during light loads conditions. The timing of the opening and closing of the valves is controlled by the Variable Cam… Read this article →

Mode $06 We are going to look at two different Ford’s for examples of misfire diagnosis using Mode $06. First we have a 1997 Ford Expedition with a 5.4 Liter Engine, the MIL is on and the engine currently runs rough. The customer states that the MIL has been ON for a while. Now it is consistently running rough and… Read this article →

How a Transmission Flush Works A transmission flush procedure is generally performed using special pressurized equipment that is connected to a vehicle. Cleaning solvent is then forced back into the transmission removing deposits of old transmission fluid from parts and components. The cooling lines, cooler, converter and other parts are all thoroughly cleaned. One of the benefits of this procedure… Read this article →

What’s Wrong With My Brakes? A high-pitched scraping or squealing noise that goes away when you step on the brake tells you that the brake pads could be worn. A grinding, metal-against-metal sound when braking indicates that your brake pads or shoes may be completely worn away, and you are now damaging the rotors or drums. If your brake pedal… Read this article →

What Will Preventative Maintenance Do For Me? Listed below are some benefits you will achieve from regular preventative maintenance: Help improve fuel economy Help your vehicle deliver peak performance at any age Find minor problems early to avoid major malfunctions later Reveal cracks, frays, leaks and bulges in belts and hoses Ensure that oil, radiator, battery, power steering, brake and… Read this article →

When is my Oil Change really due? When asked, you may hear answers such as every 3000, 5000 or 7500 miles, or when the vehicle’s oil monitor indicates that this service is necessary. It is no wonder consumers are confused. The simplest answer… well, there is no simple answer! In fact, there is no interval that applies to most vehicles.… Read this article →

Vehicle Maintenance Service Intervals R=Replace I=Inspect I/R=Inspect then Replace if needed. This schedule is appropriate for most American, European and Japanese automobiles. Information and instructions in your owner’s manual supersede this repair schedule. This guide is meant to supplement the manufacturer recommendations for your specific vehicle, and should not replace such recommendations. This is not meant for vehicle troubleshooting, repair… Read this article →

About Your Vehicle’s Tires Portland Auto Index Does Not Sell Tires – We Help You To Maintain Tire Safety This grading system, known as the Uniform Tire Quality Grading System (UTQGS), allows consumers to compare tire tread wear, traction performance, and temperature resistance. The federal government requires tire manufacturers to grade their tires in these three areas and place the… Read this article →