Intermittent idle

[dioliahary]

Thanks for the reply, I haven’t fitted the new one yet. These are the readings from the existing unit at tick over, constantly displaying these readings.

[dioliahary]

Thanks Mark, sorry I should have been clearer.
I haven’t fitted the new unit yet.
The readings that I have enclosed are from the existing unit and they are constant over time, not a snapshot.

[metalworker0]

i did not realise that the ecoblue had this vacuum EGR until went looking today at ebay listings .. i would have told you to check that first, if i had known.

Your readings point to any one of these:

EGR sticking , so needs cleaning or replacing - Note it is a service item that needs regular cleaning .. least every 20,000 miles if doing short journeys

or
The vacuum actuator device faulty, cant hold vacuum or something attached to the vacuum pipe that controls the vacuum is faulty or pipe split... cant find vac pipes in parts diagrams to look this up.

You did not say if the new EGR came with the vacuum actuator

all the best.mark

[dioliahary]

Thank you Mark.
Yes a complete unit inc vac pump.
I think that I will fit this unit and clean my old one, that way when the next service on it is due I can just replace with a clean unit.

[metalworker0]

Tech from the manual.

The exhaust gas is extracted directly at the exhaust manifold and routed through the
cylinder head runner to the EGR assembly.
The EGR assembly consists of a double-plate EGR valve, an EGR cooler for cooling the
exhaust gases and an EGR cooler bypass vacuum actuator.
A DC motor with a non-contacting position transmitter serves as the drive for the EGR
valve. The voltage signal range of the EGR valve is between 0.5 volts (valve closed) and
4.5 volts (valve fully open). The valve position and the drive are controlled using a PWM
(pulse width modulation) signal. A 10% PWM signal is required to close the EGR valve.
The EGR flow rate is adapted to specific engine operating states by the PCM (powertrain
control module) varying the EGR valve PWM signal duty cycle. A position sensor in the EGR
valve provides feedback on the exact valve positioning. This means that the PCM is able to
learn and adapt to cater for valve position changes caused by soot deposits.
The EGR cooler bypass valve (electro-pneumatic solenoid valve) enables or disables
vacuum to the EGR cooler bypass actuator (pneumatic actuator) which opens or closes to
enable or disable exhaust flow through the EGR cooler depending on the EGR requirement.
The EGR cooler bypass valve is actuated by the PCM using a PWM (pulse width modulation)
signal.
In unactuated condition, the EGR cooler bypass valve supplies ambient (no vacuum) air to
the EGR cooler bypass actuator. In this state the EGR cooler bypass actuator arm is
extended and the exhaust flow is directed through the center (bypass) passage of the EGR
cooler (no cooling).
During cold starting the recirculated exhaust gas is routed past the EGR cooler via the
bypass. As a result, the engine and catalytic converter reach their operating temperature
faster.
As soon as the engine cooling temperature reaches 50 °C or the engine speed exceeds
1750 rpm, the EGR cooler bypass valve is actuated and the system switches to cooling
mode.
In cooling mode the EGR cooler bypass valve supplies vacuum (approximately 500 mbar) to
the EGR cooler bypass actuator which opens the bypass valve against the spring load.
There is an electronic intake manifold flap upstream of the intake manifold on the fresh-air
side. It generates the necessary pressure difference between the exhaust gas and intake
sides in order to achieve the high exhaust gas recirculation rates.
The intake manifold flap (throttle body) is actuated by a DC (direct current) motor and
controlled via PWM by the PCM.
Depending on the driving situation, the volume air flow drawn in is varied in accordance
with the position of the intake manifold valve and thereby influences the composition of the
recirculated exhaust gas. Its other function is to ensure the engine does not run on when it
has been switched off.