Tuesday, 1 August 2017

Common faults with VAG vehicles with tandem fuel and vacuum pumps

Common faults with VAG vehicles with tandem fuel and vacuum pumps in the Carworkshopblog
Main parts   
This post will investigate the two most common faults that occur in the VAG group's tandem pumps.

These types of pumps are installed in those engines equipped with the pump injection system.

The tandem pump unit is a set of two pumps in one unit with very differing functions.  The entire pump assembly is driven by the camshaft.

One of the functions of the assembly is the vacuum pump; which generates the vacuum for the brake servo. The second function of the assembly is a fuel pump which sucks fuel from the fuel filter to the feed pipe located in the cylinder head and supplies the injectors.
The working pressure of this pump varies between 8 and 12 bar depending on the model.

Common faults with VAG vehicles with tandem fuel and vacuum pumps in the Carworkshopblog
The most common faults in this type of pump are as follows:

Loss of fuel.

Mixing of oil with fuel.


The repair procedures for either of the two faults are practically the same except for the additional tasks required in the case of oil and fuel mixing, which are:

  • Fuel filter replacement
  • Checking the engine oil level

 In both cases the problem can usually but not always exclusively be located in one of the gaskets or on the pumps main shaft oil seal.

Juego de juntas de la bomba Tándem en motores del Grupo VAG
Set of gaskets   

Friday, 23 June 2017

Fault in the suspension level control system fitted on Audi Q7

Fault in the suspension level control system fitted on Audi Q7
We are going to diagnose and repair a fault that affects Audi Q7 models (4L) manufactured from 2007.

These models are equipped with Adaptive Air Suspension (AAS) self-levelling suspension system.
The diagnostic fault codes recorded in the Level Control Unit (J197) are:
  • Code 1781 - Extreme inclination of the vehicle, maximum threshold value exceeded
  • Code 1400 - Level control, maximum threshold value exceeded
Fault in the suspension level control system fitted on Audi Q7

Navigator and Multi-Media Interface (MMI) Control Panel


The vehicle is unstable and wanders on the road and remains inclined to one side and the reference ride height position cannot be activated and/or adjusted on the menu on the Multi-Media Interface (MMI) screen within the vehicle.  
  • The residual pressure check valve on the spring/damper assembly remains closed.

Wednesday, 16 November 2016

The AdBlue (part II)

After having started in the above mentioned topic in this blog (consult "the AdBlue, now also for passenger cars "), on this occasion, we intend to elaborate on the structure and operation of the analysed system adopted by the different manufacturers in their vehicles.

Each manufacturer "baptises" their NOx treatment system for the diesel engine with a commercial name, normally under the umbrella of the word “Blue”.

It is worth mentioning that some makes/brands, such as Volkswagen, Audi, and Seat do not assign any name that is visible in the vehicle logo.

Reducing agent:

As noted on previous occasions, the AdBlue reducing agent is based on an aqueous solution consisting of a 32.5% urea and 67.5% water. This compound is not dangerous to people or the environment.
However, included in the features of this product we highlight two peculiarities capable of generating problems:
-Due to its high water content it freezes at -11°C.
-In contact with the air, the Adblue tends to crystallize and can cause blockages in pipes and ducts.

Summary of the operation: 
As you know, the AdBlue reducing agent is dosed directly into the exhaust pipe thanks to the electronic injector. With the exhaust temperature, the additive is transformed into ammonia and enters the SCR reduction catalytic converter. This takes care of removing the NOx by chemical reaction, transforming them into nitrogen and water. The NOx sensor located at the output of the SCR checks there are no nitrogen oxides present at the output.

Thursday, 10 November 2016

Performance of the energy recovery system of the BMW Series 1

The principle of energy recovery is based on fuel economy during engine start up and a reduction in polluting emissions from the exhaust gases. In this way, according to the driving profile, we can save up to 3% of CO2 and thus save energy.

This system is applied to the intelligent regulation control system of the alternator, also known as the IGR system by BMW.

Operating principles

Operating principles

The application of strategies in the battery charging regulation system which enables the battery to be charged only up to a defined measurement and depending on the different environmental conditions such as the outdoor temperature, the temperature inside the battery, the age of the battery, battery charge, etc. 

In this way, the constant regulation of the system prevents energy being wasted while the engine is running without repercussions on the thermal efficiency of the latter.

Operating phases

Energy recovery is carried out during the vehicle's
propulsion phases. At this time, the alternator is fully activated and generates the electrical energy that supplies the battery. Once the vehicle is launched, it does not consume fuel as the kinetic energy acts from the vehicle under propulsion to the alternator passing through the wheels and engine.

However, during the acceleration phases of the vehicle the alternator is not activated, therefore it does not use any power or fuel to produce electrical energy.

Wednesday, 2 November 2016

Noise in gearbox after engaging 5th gear

This post discusses a fault that causes a noise in the area of the vehicle's gearbox when driving on the road, until eventually the 5th gear cannot be engaged.

Affected models 
The engines motors that could be affected are the following:

Noises in the gear shifting area when driving the vehicle, regardless of the speed at which it is driven.
Problems engaging 5th speed.
Gearbox oil leak

Friday, 28 October 2016

Types of active suspension (Il). Pneumatics for the Audi A8

Audi A8 air suspension 

Air suspension allows the body to be adjusted to different heights in accordance with running requirements, it also helps the suspension and damping to adapt to the road surface and driving style.

This suspension is noted for its high flexibility, good oscillation absorption and for the self-regulation of the system that allows the distance between the chassis and the surface of the road to be maintained irrespective of the vehicle's load.

With the aid of vertical acceleration sensors on the body, this suspension model recognises the ground configuration. The driving style can be ascertained based on the vehicle's speed and the steering angle.

Three different damping programs can be selected, auto, comfort and sport. Each one is activated depending on road conditions and the driver's wishes, and contributes to driving safety and comfort. Air suspension with adaptive damping also allows each damper to be controlled independently.

Friday, 21 October 2016

Diesel pollution

There have been numerous studies published during the last decade reporting on the high levels of pollution generated by diesel engines and their possible consequences.

The public scandal and the controversy however, are a matter of the past few months. Clearly encouraged by the irresponsibility and misconduct demonstrated by the VW Group in approving some of its diesel engines with specialist software for anti-pollution testing, much of the specialist communications media investigated the topic and the results were not slow in coming.

Toxic emissions from diesel vehicles in real operating conditions exceed and multiply several times over the “expected” quantities and maximum approved values.
To this day, it might be said that the problem is widespread and includes practically all manufacturers. In the majority of cases they have taken advantage of small legal loopholes in the approval tests in order to pass the emission tests and obtain the consumption data/official emissions which, moreover, are usually those that are publicised.
Small tricks such as increasing the tyre pressures, switching off all the electrical consumers including the power steering, using specific lubricants, among others, The test cycle is carried out on rollers which has little to do with actual driving conditions, either on the highway or in the city.

Tuesday, 11 October 2016

Simos PCR 2.1 high-pressure pump engine management system

In diesel engines of the VAG group, in the 1.6 CAYC version , this electronic management system for injection of fuel is carried out using a Simos PCR 2.1 Continental Common Rail System. The high pressure pump is driven by the timing chain and the injectors are the piezoelectric type. The engine control unit controls and regulates the fuel pressure and dose. In this chapter we will discuss the high-pressure pump. 

High pressure fuel pump
This is fixed on the front right hand side of the engine and is driven by the timing belt. It is a two piston pump that works with maximum pressures of 1600 bar.

Wednesday, 5 October 2016

Towards sustainable transport

With the arrival of electric vehicles, it was suggested that developments in the sector to leave fossil fuels behind would take this line.

The biggest disadvantage is the range which these vehicles have at this time, and in the infrastructures that the different administrations provide to equip cities and roads with battery-charging stations.

Siemens (the German industrial and technology group) jointly with the Swedish lorry manufacturer Scania, will build the first electrical highway in Sweden.

With the objective of reducing dependence on fossil fuels for transporting goods by road, the Swedish Transport Administration awarded the contract to the County of Gävleborg.
The cost of the project is more than 9 million dollars of which almost 6 will come from private investment.

Wednesday, 28 September 2016

The engine does not start: Immobiliser or key error

Our Department's review of incidents has confirmed a curiosity that affects the whole range of models of Volkswagen fitted with the immobiliser-transponder system. 

DTCs are recorded with immobiliser fault and key signal not identified. Various symptoms in the performance of the vehicle's engine are added together with these fault codes.

Below are detailed all the symptoms that appear: 

VW logo.

-P0513 - Incorrect code of the immobiliser.

-P1177 - 1177 - Key, signal not plausible.

-Engine does not start occasionally.

-Warning message on the instrument panel display which states the following: “Immobilizer enabled".

NOTE: This technical note only affects vehicles fitted with a transponder-immobiliser system. 

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