Unlocking the Mysteries of Automotive Diagnostics

Unlocking the Mysteries of Automotive Diagnostics

In the intricate world of modern automotive technology, the ability to diagnose and troubleshoot issues has become an indispensable skill for both mechanics and car enthusiasts. One of the key frameworks governing this diagnostic landscape is the Onboard Diagnostics (OBD) system, specifically the second iteration, OBD-II, which adheres to the standards set by the Society of Automotive Engineers (SAE).

SAE and OBD-II Standards:

The SAE plays a crucial role in establishing standards that govern automotive diagnostics. In the context of the VW Polo and many other vehicles, OBD-II is the standardized system designed to monitor and report the performance of various vehicle systems, ensuring compliance with emission regulations.

Stoichiometry and Emission Control:

Understanding stoichiometry is fundamental to comprehending OBD-II's role in emission control. Stoichiometry refers to the chemically balanced ratio of air to fuel necessary for complete combustion. OBD-II monitors this ratio through sensors, with the Oxygen Sensor System (OXS) playing a pivotal role in providing feedback to the engine control module (ECM).

EPC Light - Electronic Power Control:

One of the telltale indicators of an issue within the electronic realm of the VW Polo is the Electronic Power Control (EPC) light. This warning light illuminates when the system detects a fault affecting the engine's performance. The EPC system is responsible for managing the throttle, ensuring optimal power delivery and efficiency.

Check Engine Light and DTC Codes:

The infamous Check Engine Light (CEL) is another beacon of concern for drivers. When illuminated, it signals potential issues with the engine or emissions system. Diagnostic Trouble Codes (DTC), communicated through the OBD-II system, provide mechanics with specific information about the nature of the problem, allowing for a targeted and efficient diagnosis.

Limp Mode and Safety Features:

In the event of a critical issue, the VW Polo employs a safety feature known as Limp Mode. This mode restricts the vehicle's performance to prevent further damage, allowing the driver to reach a service center safely. Understanding the triggers for Limp Mode requires decoding the specific DTCs stored in the OBD-II system.

Sensors, Senders, and Actuators:

Central to the OBD-II system are an array of sensors and senders strategically placed throughout the vehicle. These components, such as the Oxygen Sensor, monitor various parameters and relay information to the ECM. Actuators, controlled by the ECM, respond to these inputs by adjusting engine functions to maintain optimal performance and emissions.

16-Pin OBD-II Connector:

Mechanics rely on the 16-pin OBD-II connector to interface with the vehicle's diagnostic system. This standardized connector provides access to the wealth of information stored within the OBD-II system, facilitating precise diagnosis and troubleshooting.

Automotive Acronyms:

Navigating the world of automotive diagnostics often involves deciphering a myriad of acronyms. From EPC to DTC,to HVAC, to OXS, to EGR and beyond, mechanics adeptly use these shorthand terms to  efficiently communicate and clients and pinpoint issues with precision.However, it can confuse the hell out of them.

Delving into the realm of automotive diagnostics for the VW Polo unveils a sophisticated interplay of technologies governed by SAE standards and OBD-II protocols. Mastery of these systems empowers mechanics to unravel complexities, ensuring optimal performance and emission control for vehicles on the road. 

As technology continues to advance, a deep understanding of automotive acronyms and diagnostic intricacies remains paramount for those entrusted with keeping our vehicles running smoothly. However, it would be feasible even advisable for vehicle owners to get get up to speed with Automotive technology. Technology is here to stay and no matter how hard we try, cannot will it away.

TO CHIP OR NOT TO CHIP

TO CHIP OR NOT TO CHIP

The word chip has entered our vocabulary by force and is loosely used in everyday speech but it has absolutely nothing to do with deep fried thin potato slices or potato wedges. A chip in this sense refers to a mico-chip, as in monolithic integrated circuit, or micro computer chip, or micro processor integrated chip or just IC for short. Integrated Circuit chips or IC's first appeared in the 60's as a complete electronic circuit etched onto a small piece ("chip") of semiconductor material, embedded in a dual inline plastic package. It essentially replaced much of the circuitry dominated by silicon transistors or entire silicon transistor circuits, which started replacing vacuum tubes just a decade previously. In a nutshell, a single IC can contain hundreds or thousands, or millions, or even billions of transistors on a single piece of silicon just the size of an adults "pinky" nail, subject to its level of integration. The level of integration range from small scale integration, to large integration (LSI), to very large scale integration (VLSI), each using up to as many as a  million transistor to form logic gates, flip-flops and multiplexers.

Small integration (SSI) and LSI Analogue and digital Chips 

Over three decades, IC's metamorphosed from a meager 8 pin dual inline package, for example the analogue NE555  timer chip, to the digital but now obsolete 132-pin package i386 processor, to several other surface mounted low-profile quad flat packages (LQFP).  But within  a few short years we surpassed the Pentium 4 chip and arrived at the Intel Core i7  Thin Quad Flat Package (TQFP) processor. The most current Intel chip to date, is the  LGA 1151 Socket, Coffee Lake Quad Core Computer Processor. However, somewhere between theses two extremes, PLCC's, ROM's, PROM's, EPROM's, EEPROM's, RAM, SRAM, DSRAM, PSRAM, Flash Memory, PROFET Highside Power Switches, Microprocessors and 32-bit microcontrollers  evolved.

Some specifically designed for the automotive industry, for  use in Engine Control Module's (ECM), Electronic Control Units (ECU's) Transmission Control Units (TCU's), Anti-skid Braking System ABS units and so many other automotive controllers.  Automotive Chips have been around for several years, but is currently in great demand, and to say that this technology has evolved, is probably the understatement of the century. In fact Automotive  Chips  advancements progressed rapidly,  improved unequivocally, matured almost instantly and  became largely scalable and highly integrated. Software programming gave these Automotive Chips a degree of artificial intelligence, most of them configured by car manufacturuers for average performance to extend engine and transmission lifespans so that they would last through the warranty period. 

Stainless Steel Exhaust Downpipes 

Since Automotive Chips are programmable and configurable, many have ventured into  chipping them. Chipping an ECM / ECU for some means removing the ROM containing the ecu's stock maps and replacing it with a new chip containing maps altered for enhanced performance. However, a ECU dump can be changed with a hex-editor and the ROM can be reflashed with diagnostic software like, REVO Stage 1 Performance Software, TOAD, RomRaider, EcuFlash, VAG CAN Pro (VCP), Winols, Galletto, etc, using the appropriate Chip Tuning / Flashing Interface. Hacking an ECU  can be pretty straight forward, especially with VAG COM diagnostic tools, which permits you to find  where the various maps reside in memory, then filling them with new or experimental values. 

K&N VW Polo air Filter induction kit

This procedure is not as simple as it sounds and is best left to the tweekers who have some knowledge of MISRA C.  MISRA C is a software development standard for the C programming language specifically developed by the Motor Industry Software Reliability Association. Since ECU programming is a very specialized business, any errors or accidental changes can prove disastrous and scramble your ECU permanently, unless you have a saved ECU dump to revert back to.  ECU maps can be found strewn all over the internet especially those for older cars. But be forewarned, they may not work as expected.

Carbonised Valves before and after

Having said that, many car enthusiasts  want their cars tweaked for more power, cleaner emissions, better fuel economy and better performance, expecting at least 20% more power and at least 20% more torque. But these are not realistic expectations for non-turbo cars with a standard engine. Also chiptuning is subject to climate and atmospheric pressure meaning a engine tuned for top performance at sea level will not perform optimally at high altitudes and vise versa. Also remember that tuning for performance is at the other extreme to tuning for  economy.  According to my son, whose VW Golf 7 R was optimised  with RaceChip One for Increased Acceleration & Performance with a 76mm stainless steel downpipe, Intake Induction kit & Intercooler upgrades,  Blow Off Dump Valve Adapter Spacer Kit, DPF & EGR Removed and fitted with a Bilstein B12 Eibach 30mm/30mm Lowering Suspension Spring Pro Kit, when he speeds he can actually see his fuel level decrease as the needle races towards empty. Definitely money not well spent.



There are several chiptuning workshops strewed throughout South Africa, some better than others and some not worth their salt, all offering Volkswagen  ECU Remapping and Chip Tuning services for older and newer models. Among them are, Alpha Performance Inovation, Chiplogic, Tuned2Race, ATM Chiptuning, CPI Performance Innovation, DTE Systems SA, Wulfchiptegnik, Unichip Performance Tuners and GT Performance, etc. I've have several friends who had their VW's Chiptuned but they are definitely not happy with the results, saying that ECU Remapping and Chip Tuning is just a ripoff, it's like pouring money down a drain. 

However, for the DIY car enthusiast with an older 2.0L VW Citi Golf, weber 40mm sidedrafts, a 300deg cam  and a  solid lifter head, is a feasible performance investment that can deliver 112kw 207nm.  Add a Blow Off Dump Valve Adapter Spacer Kit to vent   extra boost air into the atmosphere instead of sending it back into the engine's intake manifold besides the WHOOOSHH sounds is really awesome!!

Blow Off Dump Valve Adapter Spacer Kit

ECU Remap via OBD port, ECU Reprogramming & Software upgrade & Chip Tuning, Injection timing, injection quantity, injection pressure, boost pressure and air mass flow, Better Throttle Response, Optimized Fuel Efficiency. Enhanced Throttle Response, GTI VW Polo GTI, VW Golf 5, VW Golf 6 R, VW Golf 6 GTI, VW Golf 7 R, VW Golf 7 GTI, VW Polo TDI, VW's Audi A4/A5/S5 Audi S3 8V Audi S3 8P  Audi RS3/TTRS Audi RS5 / RS6

KNOCK SENSORS

KNOCK SENSORS

Gone are the days when you could fix your own car with simply logic. Today you require digital logic, a scan tool  and a tech savvy mechanic to make sense of the latest cars because they are all very precisely controlled by electronic circuits. The Engine Control Module is just one such circuit and largely depends on several of its sub-circuits and associated automotive control modules to achieve the precision needed to propel the latest engines using high octane fuel, and burn it stoichiometrically in order to deliver the performance expected from these modern cars. But this is easier said than done because these sub-circuits and associated control modules rely on a number of inputs sensors and actuators distributed all over the engine and the car in general, to successfully control of the crank synchronous path.

In order for the ignition sub-system to function optimally for example, it requires feedback information about what is presently happening in the engine so that it can take corrective action if needs be, in real time. Likewise the fuel mixture sub-circuit can only determine if the mixture is rich or lean from the feedback information, then take corrective action to increase or decrease the quantity of fuel based on the amount of oxygen present. Like wise the crankshaft timing sub-circuit depends on feedback information and maintain a constant torque. Yet all three these ECM sub-circuits works very closely in conjunction with one another and other sub-circuits to achieve optimal performance. 

Restated, the ECM is in control of the torque and torque reduction circuits, which just happens to annoy the arse-mousse out of Volkswagen, Audi, SEAT and Skoda owners. It is commonly referred to as the EPC -Electronic Power Control. Essentially EPC is limp mode's best friend and vehicle owners worst enemy.  ECM torque reduction is handled via the crank synchronous path, and involve the  ignition system sensors, the knock sensors, and fuel mixture both short trim and long trim. 

Input signals are needed for calculating precise ignition timing:

1) Engine Coolant Temperature Sensor (ECT)  

2) Engine Speed Sensor (RPM)  

3) Throttle Control Valve Sensor  

4) Camshaft Position Sensors

5) Knock Sensors  

6) Accelerator pedal Position sensors


By monitoring the Engine Coolant Temperature Sensor (ECT), the ECM varies the parameters of the engine as it heats up and maintains it when it has reached the correct operating temperature. 

By monitoring Engine Speed Sensor (RPM) the ECM can determine how many times the coils misfires per 1000 revolutions and how many times the injectors fail to deliver fuel. 

By monitoring the Throttle Control Valve Sensor the ECM can calculate the torque compared to how wide the throttle opens. 

By monitoring the Camshaft Position Sensors the ECM can better determine the exact time when the valves close and the exact point of ignition. 

By monitoring the  Knock sensors the ECM decides whether detonation is bad enough to take action, either  to retard / advance the engine or reduced the torque and consequently prevent engine damage. 

By monitoring the Accelerator Pedal Position sensors it can determine synchronicity between the position of the accelerator pedal when depressed and the throttle control valve and and discrepancy outside of its normal parameters will reduce the torque. 

KNOCK SENSORS

Knock sensors are very important to the overall engine torque because they detect combustion knocks in the individual cylinders. This is common when high octane fuel self ignites  which is generally known as knocking (detonation) or pinging (pre-ignition).
Knock sensors are piezo-electric components acts something like microphones do, but instead of picking up sound,  they detect vibrations in an engine which are needed by the ECM to correct the combustion process in the event of detonation or pinging.  This allows the ECM  to "retard" the engine so that it would work with different quality fuel. This implies that lower octane fuels are more prone to knock than higher octane fuels. It is therefore imperative to use the correct octane fuel prescribed for your vehicle since failure to do so can cause the EPC light to turn on and cause the vehicle to enter into limp mode.

TESTING KNOCK SENSORS

Four and six cylinder engines have 2 knock sensors each. Knock sensor 1 monitors the even bank of cylinders while Knock sensor 2 monitors  the odd bank of cylinders. W8 and W12 engine have 4 knock sensors each.  Knock sensor 1 monitors  cylinders  1 & 2, Knock sensor 2 monitors  cylinders 3 & 4, Knock sensor 3 monitors cylinder 5 & 6, and  Knock Sensor 4 monitors cylinder  7 & 8. Knock sensors are mounted directly on the crankcase and must be torqued. Failure to torque a knock sensor may cause it to malfunction and pickup engine vibrations as well as detonations.

The plug for Knock sensor (KS) 1 is normally green and it monitors cylinders  1 & 2, whereas the plug for Knock sensor (KS) 2 is normally grey and it monitors cylinders 3 & 4. Knock sensors are three pin devices with  Pin 1 = Signal, Pin 2 = Ground and Pin 3 = Shielding. Using a multimeter measure the resistance for "short circuit" between pins 1 and 2, then 1 and 3, then 2 and 3 at the Knock sensor connector. This measurements should always read infinity (open circuit).  If short circuit, replace knock sensor and make sure that it is correctly torqued to the crankcase.  Also check the wires for short circuit. If short circuit, replace. If a oscilloscope is available, connect it between pins 1 & 2 of the knock sensor. Tap the knock sensor lightly with a wrench, this should produce a fairly high frequency irregular sinusoidal waveform with a higher amplitude towards its middle. If there is no waveform coming out of the knock sensor its best to replace it because it will lead to a rise in fuel consumption and the engine management system may reverts to emergency knock control and reduce overall engine performance.