View Full Version : EGR-ventil -87, 4L

07-21-2008, 22:22
Vakumslangen til EGR-ventilen var koblet av og plugget igjen, har koblet den på nå for å prøve finne ut forskjellen. Har noen erfaring med dette?

07-22-2008, 08:31
Her har du litt info om EGR hentet fra en `88 Factory service manual.

1983-88 Exhaust Emission Systems
Purpose of the Exhaust Gas Recirculation (EGR) system is to
limit formation of oxides of nitrogen (NOx) emissions. This is done by
reducing high peak combustion temperatures at which NOx is formed. By
reintroducing some exhaust gas back into combustion chamber, high
temperatures are avoided. Thus NOx emissions formation is reduced.
System consists of vacuum-operated EGR valve and coolant
temperature override (CTO) switch. In addition, some models are
equipped with air cleaner-mounted thermal vacuum switch (TVS), and
some are equipped with an EGR vacuum dump valve.
When the EGR valve receives vacuum signal, through the CTO
switch, EGR valve opens and meters gases from exhaust manifold into
intake manifold. Individual component operation is as follows:
EGR valve is mounted on intake manifold. Exhaust gas is drawn
from exhaust crossover passage or exhaust manifold. Two types of EGR
valves are used: valve without backpressure sensor and valve with
integral backpressure sensor.
EGR Valve W/O Integral Backpressure Sensor
EGR valves are calibrated by use of different shapes of valve
pintles or orifices. Valve is normally held closed by spring (above
diaphragm). Valve opens by overcoming spring tension when vacuum is
sensed through coolant temperature override switch (CTO) and
backpressure sensor (if equipped).
EGR Valve W/Integral Backpressure Sensor
Calibration is accomplished by use of different diaphragm
spring loads and flow control orifices. This integral type unit
combines EGR valve and backpressure sensor functions into one
component. Restrictor plate is required with some engines.
Exhaust gas exerts backpressure inside exhaust manifold
whenever engine is running. This pressure is conducted through hollow
pintle stem into EGR diaphragm control chamber. If this pressure is
great enough to overcome spring tension against diaphragm, diaphragm
is moved against bleed valve and exhaust gas flow begins.
Coolant temperature override (CTO) switch is located in
coolant passage at cylinder head or coolant passage at intake
Inner port of switch is connected to EGR port on intake
manifold and outer port is connected to EGR valve, or EGR-TVS. Switch
opens at a preset temperature. Below these temperatures, no EGR is

Used on some models, EGR dump valve is connected in series
with vacuum source and EGR valve. Valve is used to eliminate EGR
function at low vacuum levels. When vacuum drops below predetermined
level, valve "dumps" vacuum rather than allowing it to flow to EGR

Valve Opening Test
1) With engine at normal operating temperature and at idle,
rapidly open and close throttle. Open throttle sufficiently to obtain
at least 1500 RPM. Movement should be noticed in EGR diaphragm.
2) If diaphragm does not move, probable causes are: faulty
vacuum signal to EGR, defective EGR diaphragm or defective
backpressure sensor diaphragm (if equipped), or leaks in vacuum lines
or connections.
Valve Closing Test
1) With engine at normal operating temperature and at idle,
manually depress EGR valve diaphragm. RPM should immediately drop,
indicating that EGR valve is not leaking and had been properly cutting
off exhaust gas flow at idle.
2) If there is no change in RPM and engine is idling
properly, exhaust gases are not reaching combustion chamber. Check for
plugged passage between EGR valve and intake manifold.
3) If engine idles poorly and RPM is not greatly affected by
manually moving diaphragm up, EGR valve is not closing off exhaust gas
flow. Check for carbon between pintle, leaking EGR valve gasket or bad
EGR valve.
NOTE: Engine coolant temperature must be below 100 �� F (38 �� C) to
perform this test.
1) Check vacuum lines for leaks and correct routing.
Disconnect vacuum line at backpressure sensor (if equipped) or at EGR
valve, and attach this line to vacuum gauge.
2) Operate engine at 1500 RPM. No vacuum should be indicated
on gauge. If vacuum is shown, replace CTO switch.
3) Idle engine until coolant temperature exceeds 100 �� F (38 �� C)
on 4-cylinder engines, or 115 �� F (46 �� C) on 6-cylinder and V8 engines.
4) Raise engine speed to 1500 RPM. Ported vacuum should be
shown on gauge. If not, replace CTO switch.
1) With engine at normal operating temperature, remove dump
valve vacuum hose from manifold and plug manifold connection.
2) Raise engine speed to 2000 RPM. Vacuum should be present
at exhaust ports on bottom of valve. If not, replace valve.
3) Reconnect vacuum hose to manifold and raise engine speed
to 2000 RPM. No vacuum should be felt at exhaust ports on bottom of
valve. If vacuum is present, replace valve.
1) With the air cleaner temperature below 40 �� F (-4 �� C),
disconnect vacuum hoses from TVS and connect vacuum source to large
2) Apply vacuum to TVS. TVS should hold vacuum. If not,
replace TVS.
3) Start engine and warm air cleaner to 55 �� F (13 �� C), or
greater. TVS should not hold vacuum. If it does, replace TVS.

07-24-2008, 17:19
Takk, det var ikke lite:smile:
Har dette noe effekt på forbruk? Den eneste forskjell jeg har lagt merke til er at den detter fort ned i turtall etter start, noe lenger tid da den var "plugget". Lavere forbruk jo bedre-med dagens priser:pissed: