Tip & How-To about Mercedes-Benz E-Class

EGR Exhaust Gas Recirculation valve

1.6) EGR - Exhaust Gas Recirculation valve (actuator)

What is it? This is a device that reduces engine emissions of nitric oxides by allowing a measured amount of exhaust gas to re-enter the intake manifold and mix with the air prior to entering the cylinders. The EGR can be vacuum (older types) or electrically driven (modern) or a hybrid combination of both (intermediate age). Adding inert exhaust gas to the intake charge artificially enriches the fuel air mix (by diluting the air) and thereby reduces ignition temperatures associated with lean running conditions

Where is it located? The EGR is associated with the intake manifold. The EGR is sited at a point of contact with both the exhaust and intake manifolds. If the exhaust manifold is remote to the inlet manifold, for example onthe other side of the engine, an exhaust feed pipe leading from the exhaustmanifold to the EGR is provided.

How does it work? Generally intake manifold vacuum acting on a diaphragm draws up on a pintle valve to open a connection between a (usually round) entry port for the exhaust gases and an exit port (usually rectangular) to the intake manifold. The opening of some modern EGR valves iscompletely under the (ECU) control of an electrical motor/solenoid. Since an open EGR port effectively acts as a vacuum leak in the inlet manifold leading to potential starting and idling difficulties, the EGR valve operation is often impeded by an electrical over-ride at cold/start-up until the engine reaches running temperature and high revs. The ECU takes signals from the coolant temperature sensor to determine when the engine is hot before allowing the EGR to function. In some cases, a differential pressurefeedback exhaust (DPFE) sensor, connected to pipes on the exhaust feed to the EGR, informs the ECU when and by how much the EGR should be open.

NEXT 1.6b) EGR faults and how to fix

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I have a 1999 Chevy S10 2.2L 4Cyl extreme. I can not find or locate the EGR Valve any where,I am pretty sure it does not have one, I wanted to confirm or discuss this with a fixian expert like myself?


Doesn't have EGR valve . How many miles on the truck ?
What Causes High NO (NOx)? Nitrogen Oxide or NO is created when an engine's combustion chamber temperature reaches over 2500F. Vehicle manufacturers have designed several systems, which when working properly, lower nitric oxide emissions. Below are common failures which may cause your car, truck, van, suv, or motorhome to produce high high nitric oxide. 1. Lean Fuel Mixture - Lean fuel mixtures cause high NOx. A lean fuel mixture exists when less fuel then required is delivered to the combustion chambers or when more air then necessary is added to the fuel. In either case the lack of gasoline needed to cool the combustion chambers down is not present. Combustion temperatures increase causing high nitric oxide emissions. A lean fuel condition may be due to a vacuum leak/s and/or defective fuel control components, such as the Air Flow Meter, Engine Coolant Temperature Sensor, and O2 sensors. Read about Oxygen Sensor.
2. Defective EGR System- The Exhaust Gas Recirculation system is designed to reduce NO. The EGR system consists of an EGR valve, EGR pressure sensor, vacuum hoses, and one or more vacuum switching valves or solenoids. Later model vehicles may be equipped with electronically controlled EGR valves, which do not require vacuum lines or switching solenoids. Electronic EGR systems will have these components built in.
The EGR system's job is to re-route a small amount of exhaust gas back into the intake manifold to help reduce combustion chamber temperatures. As mentioned above NOx is created when combustion chamber temperatures reach above 2500F. By recirculating exhaust gas back into the intake, a small amount of the air/fuel mixture is replaced with inert gas, reducing combustion temperatures. Read about EGR System.
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3. Defective Catalytic Converter (CAT) Some vehicle manufactures have designed their cars to operate without EGR valves. Non-EGR equipped vehicles rely heavily on the Catalytic Converter to assist in the reduction of NO. These vehicles have tendencies to develop CAT problems sooner then those which are equipped. If you own a non-EGR equipped vehicle, and have failed the emissions test for high NOx, pay close attention to the Catalytic Converter. Read about Catalytic Converter
4. High Engine Mileage - Over an engine's lifetime, carbon build-up develops in the engine's combustion chambers. The more miles on your engine, the more carbon build-up on the pistons, cylinder heads and valves. Carbon build-up decreases the available space for the air/fuel mixture to combust, and causes higher cylinder compression. High compression results in high temperatures and high NOx. Keep in mind this problem is usually seen in vehicles with over 150,000 miles which have been poorly maintained. The solution to this problem is called De-Carbonizing. It usually costs around two labor hours at a smog check repair station. It will remove a good amount of carbon out of an engine. This will increase combustion space, lower compression and lower NOx.
5. Engine Overheating - Inadequate engine cooling can will high NOx. If your vehicle's cooling system is not working efficiently, (i.e. bad radiator, thermostat, hoses) high NOx will be created. Remember high NOx nitric oxide is created when an engine's combustion chamber temperatures reach over 2500F. You will want to make sure your vehicle's cooling system is working properly, and your vehicle's temperature gauge is always indicating normal.

Feb 24, 2018 | 1999 Chevrolet S-10 Pickup

1 Answer

where is the 2.5 d4d erg valve mounted on the engine


In internal combustion engines,exhaust gas recirculation (EGR) is a nitrogen oxide (NOx) emissions reduction technique used in petrol/gasoline and diesel engines.EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. Thers a hose going down the rear of the engine to the exhaust pipe. It recirculates the portion of the gasses coming out of the engine by putting in back into the intake manifold, where the engine can burn it again, thereby reducing the emissions. The EGR valve is located in the engine compartment (underneath the hood). Usually on the side with the air intake manifold attatched to the side frame rail

Mar 08, 2017 | Cars & Trucks

3 Answers

96 ford explorer failed emissions test with codes p0401,p0402,p0755,p0756


P0401
EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.

P0402
EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor (DPF). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0402 code means that OBD detected an excessive amount of EGR.

There sound like a bad EGR and need replace it.

P0755 Shift Solenoid B Malfunction and P0756 Shift Solenoid B Performance or Stuck Off. First I suggtes check leve fluids and preventive maintenance.

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Sep 02, 2010 | Ford Explorer Cars & Trucks

1 Answer

1995 mercury villager check engine code p1200 injector open


P0400 = EGR Flow
P0325 = knock sensor (Do not ever change a knock sensor, they don't affect anything and cost $600 to replace for absolutely no gain)
P1200 = I can't find this one. I think it's injector flow
report back on what you find.
Egr flow may be plugged egr passages or a bad solenoid.
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1996 PCED OBDII-Villager SECTION 1B: Description and Operation
Exhaust Gas Recirculation System
Exhaust Gas Recirculation (EGR) System Operation The exhaust gas recirculation (EGR) system (Figure 1 below) recirculates a portion of the exhaust gases into the intake manifold under average vehicle driving conditions to reduce combustion temperatures and exhaust gas NOx content. The amount of exhaust gas recirculated varies according to operating conditions and will be cut completely under:
  • Engine starting condition
  • Low engine coolant temperature condition
  • Excessively high engine coolant temperature condition
  • Engine idling condition
  • High engine speed condition
  • Mass air flow sensor failure
The exhaust gas recirculation (EGR) system on the Villager uses the exhaust gas recirculation/evaporative emission (EGR/EVAP) control solenoid valve to provide vacuum to both the EGR valve and the EVAP canister when commanded by the PCM. If the exhaust backpressure is sufficient to close the EGR backpressure transducer valve, vacuum is sent to the EGR valve and allows EGR gas to flow into the intake manifold. If the exhaust backpressure is not sufficient, the EGR backpressure transducer will remain open and allow vacuum from the EGR/EVAP control solenoid to vent to the atmosphere.
The EGR system monitor, for OBD II regulations, uses an EGR temperature sensor to monitor the EGR system. The EGR temperature sensor is a thermister located in the EGR passageway. When hot exhaust gas is recirculated into the engine, the temperature at the EGR passageway increases. This increase is sensed by the EGR temperature sensor and a signal is sent to the PCM to indicate EGR flow. If the EGR temperature sensor does not detect EGR flow when commanded by the PCM after two consecutive drive cycles, the malfunction indicator lamp (MIL) will be illuminated and a diagnostic trouble code (DTC) will be stored. The MIL will be turned off after three consecutive drive cycles are completed with no malfunctions detected. The DTC will remain stored in the PCM memory until 80 drive cycles have been completed without the same malfunction detected in the system.
Figure 1: Exhaust Gas Recirculation (EGR) System Diagram Item Number Description 1 — EGR/EVAP Control Solenoid 2 — Air Cleaner Housing 3 — Throttle Valve 4 — EGR Temperature Sensor 5 — EGR Valve 6 — EGR Backpressure Transducer 7 — EVAP Canister
Exhaust Gas Recirculation (EGR) Backpressure Transducer Valve The exhaust gas recirculation (EGR) backpressure transducer valve is used to control EGR. The EGR valve is operated by ported vacuum, but the ported vacuum will normally be vented off at the EGR backpressure transducer valve. As rpm increases, exhaust pressure increases and pushes on the diaphragm in the EGR backpressure transducer valve and closes the vacuum vent.
Figure 2: EGR Backpressure Transducer Value
Item Number Description 1 — Throttle Valve 2 — Vacuum Port 3 9D475 EGR Valve 4 9F452 EGR Backpressure Transducer Valve 5 — EVAP Canister 6 — EGR/EVAP Control Solenoid 7 — Vent
EGR/EVAP Control Solenoid The exhaust gas recirculation/evaporative emission (EGR/EVAP) control solenoid (Figure 3) is controlled by the powertrain control module (PCM). The EGR/EVAP control solenoid controls vacuum to both the exhaust gas recirculation (EGR) valve and to the evaporative (EVAP) emission canister. When the EGR/EVAP control solenoid is off (12 V signal from the PCM) vacuum is supplied to both the EGR valve and to the EVAP canister. When the EGR/EVAP control solenoid is on (ground supplied by PCM) vacuum is vented to the atmosphere keeping the EGR valve closed and no vacuum to the EVAP canister. The PCM will command the EGR/EVAP control solenoid on at:
  • Engine starting condition
  • Low engine coolant temperature condition
  • Excessively high engine coolant temperature condition
  • Engine idling condition
  • High engine speed condition
  • Mass air flow sensor failure
Figure 3: Exhaust Gas Recirculation/Evaporative Emission (EGR/EVAP) Control Solenoid
Exhaust Gas Recirculation (EGR) Temperature Sensor
The exhaust gas recirculation (EGR) temperature sensor (Figure 4) is a thermister type sensor that monitors the temperature of the exhaust in the EGR passageway. As the EGR flow increases, the temperature increases. This process creates a change in the resistance of the sensor, which decreases as the temperature increases. The signal is sent to the powertrain control module (PCM) to indicate that the EGR system is working properly. If the EGR temperature sensor does not change resistance as the PCM expects on two consecutive drives, the malfunction indicator lamp (MIL) will be illuminated and a diagnostic trouble code (DTC) will be stored.
Figure 4: EGR Temperature Sensor Exhaust Gas Recirculation (EGR) Valve
The exhaust gas recirculation (EGR) valve (Figure 5) recirculates portions of the exhaust gas back into the intake manifold to reduce the amount of the NOx released during combustion and to reduce combustion temperature. The amount of exhaust gases that are released into the engine is proportional to the load on the engine.
Figure 5: EGR Valve

Mar 20, 2009 | 1995 Mercury Villager

1 Answer

check engine light on - P0400 malfunction


Exhaust Gas Recirculation (EGR) System The exhaust gas recirculation (EGR) system recirculates exhaust gas into the intake manifold (9424). This lowers combustion temperatures and reduces the formation of oxides of nitrogen (NOX). The amount of exhaust gas reintroduced and the timing of the cycle varies by calibration. Timing and volume are controlled by the powertrain control module (PCM) (12A650). The EGR valve (EGR valve) (9D475) is vacuum actuated. The vacuum hose routing diagram is shown on the Vehicle Emission Control Information (VECI) decal. EGR operation stops when the engine temperature is cold, to improve driveability. The PCM controls the EGR solenoid vacuum valve (9D474). When energized the intake manifold vacuum outlet fitting and cap (9A474) allows exhaust gas to be circulated in the engine to be burned.

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Oct 20, 2008 | 1997 Ford Aspire

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