How To Clean 2002 Gmc Savana Egr With 4.3 Litre V 6

Integral to the vehicle'south engine management organization, the aptly named exhaust gas recirculation valve, or EGR valve for short, recirculates finely metered quantities of exhaust gas to the engine intake system for increased engine efficiency, reduced fuel consumption and lower NOx emissions.

With growing pressures to reduce emissions, the EGR valve will play an increasingly important office moving frontward. Information technology's important to know what it does, why it fails and how to replace it when it does.

How does an EGR valve work?

EGR valve with four examples of harsh environment - corrosion, extreme heat, contamination and wear. — Examples of harsh environments for EGR valves.

Nearly lxxx pct of the air we breathe is nitrogen. However, when information technology is exposed to the extremely loftier temperatures in the combustion bedchamber, plus 1370°C, the ordinarily inert gas becomes reactive, creating harmful oxides of nitrogen or NOx, which are and then passed through the exhaust organization into the atmosphere.

To help minimize this, the EGR valve allows a precise quantity of exhaust gas to re-enter the intake the organisation, effectively changing the chemical makeup of the air entering the engine. With less oxygen, the now diluted mixture burns slower, lowering temperatures in the combustion bedchamber by almost 150°C, and reducing NOx product for a cleaner, more efficient frazzle.

The EGR valve has 2 master settings: open and closed, although the position can vary anywhere in between. The EGR valve is closed when the engine is starting upward. During idle and at low speeds, only a pocket-sized corporeality of power is required, and therefore but a pocket-size amount of oxygen, then the valve gradually opens – it can be up to 90% open at idle. However every bit more torque and ability is required, for example during total acceleration, the EGR valve closes to ensure as much oxygen enters the cylinder.

As well are reducing NOx, EGR valves can be used in downsized GDi engines to reduce pumping losses and improve both combustion efficiency and knock tolerance. In diesel, it can also assistance to reduce diesel knock at idle.

Types of EGR valve

Although there are several types of EGR valve -- earlier systems use a vacuum-operated valve, while newer vehicles are electronically controlled -- the main types tin exist broadly summarized as:

Diesel high pressure EGR valves divert the high-flow, loftier-soot exhaust gas before it enters the diesel particulate filter – the soot can combine with the oil vapor to create sludge. The gas is then passed back to the inlet manifold either via a piping or internal drillings in the cylinder caput. A secondary valve is too used to assist create a vacuum in the inlet manifold as this is non naturally present on diesel engines.

Diesel Low pressure EGR valves divert the exhaust gas subsequently it has passed through the diesel fuel particulate filter -- this gas has a lower flow simply is almost completely clean of soot. The gas is so passed back to the inlet manifold via a pipe.

Gasoline EGR valves divert the exhaust gases, much like the loftier pressure diesel equivalent. The vacuum created past cylinder low, draws the exhaust gases in and the catamenia is regulated by the opening and closing of the EGR valve itself.

Vacuum operated EGR valves utilise a vacuum solenoid to vary the vacuum to the diaphragm and, in turn, open and close the EGR. Some valves besides include a feedback sensor to inform the ECU of the valves position.

Digital EGR valves characteristic a solenoid or stepper motor and, in almost cases, a feedback sensor. These valves receive a pulse width modulated signal from the ECU, to regulate exhaust gas flow.

Why exercise EGR valves fail?

EGR valves operate in a hostile environment so over time will experience habiliment and tear. However, the unmarried biggest crusade of failure is the buildup of carbon particles from the frazzle gases along the EGR and intake arrangement passages. Over time this will clog tubes, exhaust gas channels and eventually the valve's plunger machinery, causing it to either stick open or shut. Failures tin also be caused by a rupture or leak in the valve diaphragm.

What to look out for in a failing EGR valve?

The symptoms associated with EGR valve failure are like to those of many other engine management components, and considering of this EGR faults proceed to be a source of headaches for many technicians. However, there are a few signs to look out for:

Check engine light: every bit with well-nigh engine management components, a problem with the EGR valve may trigger the check engine calorie-free.
Engine performance bug: if the valve is stuck open the vehicle's air-fuel ratio will exist disrupted causing engine performance issues such every bit reduced power, poor acceleration and crude idle. It may as well produce turbo heave pressure leaks, causing the turbo to work harder.
Increased NOx emissions: when the EGR valve remains shut, the resultant high temperatures in the combustion chamber will go out a lot of unburned fuel in the exhaust, leading to increased NOx emissions and reduced fuel efficiency.
Engine knock: the higher temperatures and NOx may as well result in increased detonation or knock, heard as knocking noises in the engine.

Troubleshooting an EGR valve

Given the different types of EGR valves, it is always best to follow the troubleshooting procedures detailed in the service manual, nevertheless, there are a few generic steps that tin can help to pinpoint diagnosis:

Read whatever fault codes on electronically controlled EGR valves using a diagnostic tool.
Check that all vacuum lines and electrical connections are connected and positioned correctly.
Apply a vacuum gauge to bank check the vacuum supply hose for vacuum at 2000 to 2500 rpm. No vacuum at normal operating temperatures would suggest a loose hose, a blocked or faulty ported vacuum switch or solenoid or a faulty vacuum amplifier/pump.
Check the vacuum solenoid while engine is running. On electronically controlled EGR valves, activate the solenoid with a scan tool and cheque the vacuum at stop of pipe. If the solenoid does not open when energized, is stuck in the open or closed position or has a corroded electrical connectedness, loose wire or bad ground, EGR functioning volition exist affected. Identify the root crusade earlier replacing.
If possible, cheque the motility of the valve stalk at 1500 to 2000 rpm. The valve stem should move if the valve is functioning correctly – if non, and at that place's vacuum, there's a error.
Utilise vacuum straight to the EGR valve using either a hand vacuum pump or scan tool depending on the type of EGR valve. If there is no modify in idle quality, so either the EGR valve is faulty or the passages are completely restricted. If the engine idles rough or stalls, the problem is being caused past a malfunctioning control system.
Remove the EGR valve and bank check for carbon build up. Where possible, remove whatever carbon, being careful not to contaminate the diaphragm.
Inspect the EGR passageway in the manifold for bottleneck and make clean if required.

Common EGR fault codes

On late model EGR valves the following fault codes are common:

P0400: EGR flow malfunction
P0401: EGR bereft flow detected
P0402: EGR excessive flow detected
P0403: EGR circuit malfunction
P0404: EGR circuit range/performance
P0405: EGR sensor A circuit low
P0406: EGR sensor A circuit high
P0407: EGR sensor B circuit low
P0408: EGR sensor B circuit loftier
P1403: EGR solenoid low
P1404: EGR system – airtight valve pintle error
P1405: EGR solenoid high
P1406: EGR system pintle position error

How to replace a faulty EGR valve?

First remove the engine cover.
Then loosen the electrical cable on the valve and remove the electrical connections and/or vacuum lines, checking for signs of harm.
Remove the fastening screws and check the valve for harm, corrosion or carbon build-up.
Clean the EGR valve mounting surface thoroughly and fit new valve and gasket. Remove whatsoever loose carbon from the EGR supply port likewise.
Line upward the EGR valve with the bolt holes and gasket and reattach to the housing.
Tighten all fasteners to the recommended torque settings.
One time firmly seated, reconnect the vacuum lines and/or electrical connections.
Finally employ a diagnostic scan tool to reset the engine direction light and check for any other errors. Bank check that the malfunction indicator lamp has been extinguished, and then behave out a road test. Many vehicles now require the EGR valve to exist reset under adaptations. This simply allows the ECU to larn the stop position at the open up and closed points. Failure to exercise this can crusade the valve to break and fall into the manifold.