Volvo Parts Catalog Volvo Accessories Catalog Volvo Technical Articles Volvo Tech Forums
 
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Engine Management Systems
 
Bookmark and Share

Pelican Technical Article:

Engine Management Systems

Nick Czerula

Time:

1 hours1 hrs

Tab:

$300

Talent:

*****

Tools:

ECM flash tool, supplied with software

Applicable Models:

Volvo V70 (1998-01)
Volvo V70 2.4T (2001)
Volvo V70 AWD (1998-99)
Volvo V70 GLT (1998-00)
Volvo V70 GLT SE (2000)
Volvo V70 R (1998)
Volvo V70 R AWD (1999-00)
Volvo V70 T5 (1998-01)
Volvo V70 X/C (2001)
Volvo V70 X/C AWD (1998-00)
Volvo V70 X/C AWD SE (2000)

Parts Required:

DME flash tool and software

Hot Tip:

Use this info to better understand your BMW E60 engine

Performance Gain:

Fuel economy and performance

Complementary Modification:

Upgrade DME software

Volvo V70 engine management systems -- an overview (1999: 2001)

Starting in 1990, Volvo 4-cylinder, 5-cylinder and 6-cylinder engines formed a family of engines with shared characteristics: Each is straight across (L-design rather than V-design) with aluminum block and cylinder head and fracture-split forged steel connecting rods.

Volvo V70 cars (1999 - 2001 V70, V70 XC and XC70) are equipped with straight-5 cylinder engines and Bosch or Siemens digital engine management systems and drive-by-wire electronic throttle. The engine control module (ECM) in these systems is programmed with software for control of fuel injection, ignition, variable camshaft control and other functions. Volvo engine management systems comply with second-generation on-board diagnostics (OBD II) standards. The table below summarizes the engines used in V70 cars:

Years, Models

Engine

1999

V70

L5 2.4 liter 5-cylinder

V70 AWD

V70 GLT

V70 XC AWD

L5 2.4 liter 5-cylinder low-pressure turbocharged

V70 T5

V70R AWD

L5 2.3 liter 5-cylinder high pressure turbocharged

2000

V70

L5 2.4 liter 5-cylinder

V70 AWD

L5 2.5 liter 5-cylinder turbocharged

V70 GLT

V70 XC AWD

L5 2.4 liter 5-cylinder turbocharged

V70 T5

V70R AWD

L5 2.3 liter 5-cylinder high pressure turbocharged

2001

V70 2.4

L5 2.4 liter 5-cylinder

V70 2.4T

L5 2.4 liter 5-cylinder low-pressure turbocharged

V70 T5

L5 2.3 liter 5-cylinder high pressure turbocharged

V70 XC AWD

L5 2.4 liter 5-cylinder low-pressure turbocharged

Engine control module (ECM)

The engine control module (red arrow) (ECM) is mounted in the control module box on the right side of the engine compartment. When checking the ECM, do not remove the control module from the car before the main relay has interrupted the power supply. This may take up to 4 minutes after the ignition has been switched off and the engine-cooling fan has stopped running.

Fuel supply, fuel injection

An electrically operated fuel pump, located inside the fuel tank, supplies high-pressure fuel to the engine fuel rail. Nominal system fuel pressure (engine not running) is as follows:

Naturally aspirated engine: 3.0 bar (43.5 psi)

Turbocharged engine: 3.75: 3.95 bar (54.4: 57.3 psi)

The fuel rail in turn distributes fuel to the electronically actuated fuel injectors.

The ECM meters the fuel output of injectors using pulse width signals. It varies the pulse width based on input signals. Inputs to the ECM include:

Air intake amount using mass airflow sensor signal

Ambient and coolant temperature signals

Accelerator pedal signal

Crankshaft and camshaft position signals

Knock sensor signals

When the engine is shut off, fuel pressure in the system drops, but check-valves in the system prevent complete loss of fuel pressure. Residual pressure in the fuel lines aids in quick starts, particularly if the engine is hot. Residual fuel pressure is within 20 minutes of the fuel pump being shut off:

Approx 2.0 bar (29 psi)

Engine airflow

The engine control module (ECM) detects the amount of engine intake air via a signal from the hot wire mass airflow (MAF) sensor located between the air filter housing and the intake manifold in the intake air stream. MAF data, including intake air temperature data is used to calculate the following:

Length of injection time for each fuel injector

Ignition timing

Engine load

Gearshift calculation -- this function is controlled by the transmission control module (TCM), which receives MAF data via CAN bus

The MAF is supplied battery voltage using the engine management system relay. The MAF ground is in the ECM. The MAF signal is analog and varies between 0.5 v and 4.5 v, depending on the mass of the intake air. Low airflow produces low voltage; high air flow leads to high voltage.

The hot wire of the MAF (its main functional component) has a ceramic casing and is therefore self-cleaning.

Variable camshaft timing

Variable camshaft timing, controlled by the ECM, offers the following advantages:

Increased power

Higher low end and medium speed torque

Improved idle and fuel efficiency

Quicker warm-up and lower emissions

The change in camshaft timing relative to the crankshaft is calculated by the use of engine load and rpm information, camshaft and crankshaft position sensor data and engine coolant temperature.

Engine oil pressure is used to actuate camshaft position change. Oil pressure is related to operating temperature and oil condition. The ECM monitors camshaft position continually and detects the time it takes the camshaft to deflect when the signal to deflect is issued. If the time exceeds a programmed maximum, the signal to vary camshaft timing is cancelled or changed.

Throttle control, idle control

In V70 vehicles the throttle cable is eliminated and throttle actuation is completely electronic (drive-by-wire).

The accelerator pedal position sensor provides 2 signals to the ECM: A digital pulse width modulated signal and an analog linear signal.

Ignition and knock control

The ignition system uses one ignition coil per cylinder, with each coil mounted above a spark plug. Spark timing is controlled by the ECM using an ignition spark "map". Spark timing is not adjustable.

The firing order in 5-cylinder engines is 1-2-4-5-3.

To prevent engine damage in case of adverse conditions or poor fuel quality, knock (detonation) sensors are mounted on the engine crankcase below the intake manifold. These are microphones tuned to the frequency of engine knock and communicate such knock to the ECM. The ECM can respond to these signals by changing (usually retarding) ignition timing at one or more cylinders.

1999: 2000 models are equipped with one knock sensor. From 2001 V70 cars are equipped with two knock sensors each.

Oxygen sensors

Oxygen sensors are installed in the exhaust stream to measure oxygen density in the exhaust both before and after the catalytic converter. Oxygen sensor signals are used by the ECM to control fuel delivery. The sensors work correctly once they reach operating temperature. They are electrically heated to reach operating temperature as quickly after a cold start as possible.

The 5-cylinder V70 engine is equipped with two oxygen sensors. The sensor in front of the catalytic converter is used to monitor oxygen density in the exhaust stream as it leaves the exhaust manifold. This sensor, referred to as zirconia type, outputs a small voltage, approximately 0.1: 0.8 v, in response to oxygen density. Based on the voltage it receives, the ECM determines whether to increase or decrease the amount of fuel it injects in order to approximate the ideal (stoichiometric) ratio of 15 parts air / 1 part fuel (by weight). The air / fuel mixture ratio is raised or lowered until the oxygen sensor signals that the mixture has overshot the ideal and the ECM reverses direction on the ratio. This pulsing from slightly too rich to slightly too lean mixture is called "closed loop."

The rear sensor monitors oxygen density in the exhaust stream after it leaves the catalyst. With the catalyst operating correctly, nearly all the oxygen in the exhaust should be used up inside the catalyst as it combines with the unburned exhaust gases. The rear oxygen sensor should detect a stream of exhaust with fairly steady low oxygen content. This indicates a correctly functioning engine management system and a healthy catalyst. If the oxygen content after the catalyst becomes too high and begins to fluctuate in sync with the front oxygen sensor, then it is an indication that the catalyst is failing.

Later V70 models were equipped with a front oxygen sensor, in front of the catalytic converter, referred to as air / fuel ratio or A/F sensor. This type of sensor signals oxygen concentration by varying the amount of current it produces precisely in response to oxygen concentration in the exhaust.

Fault codes, malfunction indicator light (MIL)

OBD II compliant engine management systems are designed to self-diagnose and, when a fault in a system or function is detected, to store a diagnostic trouble code (DTC) for later access and diagnostic work. In some cases, if a DTC is detected because of a severely malfunctioning component, a substitute value for the malfunctioning or missing signal is supplied so that the vehicle can be limped home.

Emissions related DTCs also cause the malfunction indicator light (MIL) on the dashboard to illuminate. This light is variously called the "Check Engine" or "Service Engine Soon" light. When this light is lit, the vehicle needs to be hooked up to a diagnostic scan tool so that the DTCs can be downloaded and evaluated and faulty components repaired or replaced.

Engine control module (ECM): The engine control module (red arrow) (ECM) is mounted in the control module box on the right side of the engine compartment.
Figure 1

Engine control module (ECM): The engine control module (red arrow) (ECM) is mounted in the control module box on the right side of the engine compartment. When checking the ECM, do not remove the control module from the car before the main relay has interrupted the power supply. This may take up to 4 minutes after the ignition has been switched off and the engine-cooling fan has stopped running.

Engine airflow: The engine control module (ECM) detects the amount of engine intake air via a signal from the hot wire mass airflow (red arrow) (MAF) sensor located between the air filter housing and the intake manifold in the intake air stream.
Figure 2

Engine airflow: The engine control module (ECM) detects the amount of engine intake air via a signal from the hot wire mass airflow (red arrow) (MAF) sensor located between the air filter housing and the intake manifold in the intake air stream.

Throttle control, idle control: In V70 vehicles the throttle cable is eliminated and throttle actuation is completely electronic (drive-by-wire) via an electronic throttle housing (red arrow).
Figure 3

Throttle control, idle control: In V70 vehicles the throttle cable is eliminated and throttle actuation is completely electronic (drive-by-wire) via an electronic throttle housing (red arrow).

Ignition and knock control: The ignition system uses one ignition coil per cylinder (green arrows), with each coil mounted above a spark plug.
Figure 4

Ignition and knock control: The ignition system uses one ignition coil per cylinder (green arrows), with each coil mounted above a spark plug. Spark timing is controlled by the ECM using an ignition spark "map". Spark timing is not adjustable. The firing order in 5-cylinder engines is 1-2-4-5-3.

Oxygen sensors Oxygen sensors are installed in the exhaust stream to measure oxygen density in the exhaust both before (green arrow) and after (red arrow) the catalytic converter.
Figure 5

Oxygen sensors Oxygen sensors are installed in the exhaust stream to measure oxygen density in the exhaust both before (green arrow) and after (red arrow) the catalytic converter. Oxygen sensor signals are used by the ECM to control fuel delivery. The sensors work correctly once they reach operating temperature. They are electrically heated to reach operating temperature as quickly after a cold start as possible. The 5-cylinder V70 engine is equipped with two oxygen sensors. The sensor in front of the catalytic converter is used to monitor oxygen density in the exhaust stream as it leaves the exhaust manifold. This sensor, referred to as zirconia type, outputs a small voltage, approximately 0.1: 0.8 v, in response to oxygen density. Based on the voltage it receives, the ECM determines whether to increase or decrease the amount of fuel it injects in order to approximate the ideal (stoichiometric) ratio of 15 parts air / 1 part fuel (by weight). The air / fuel mixture ratio is raised or lowered until the oxygen sensor signals that the mixture has overshot the ideal and the ECM reverses direction on the ratio. This pulsing from slightly too rich to slightly too lean mixture is called "closed loop."



Bookmark and Share
Comments and Suggestions:
gmavery Comments: Thanks, for the good information. It is much appreciated. Gary Avery of Lincoln Nebraska
November 11, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Wed 12/7/2016 02:52:53 AM