EGR

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Exhaust Gas Recirculation (EGR) was first used starting with 1974 B-210 (North American B210) models. Australia 1200 utes got EGR in 1982. Japan 1200 trucks got it in 1989. It recirculates a small portion of the exhaust back into the combustion chamber. Although this dilutes the the air/fuel mixture (reducing performance), it reduces burning temperatures resulting in drastic reductions of Oxides of Nitrogen (NOx).

Overview

EGR is a key emission control technology. Even the new 2012 models use EGR, although now it can be effected by variable camshaft overlap and engine computer control. Datsuns use an early version of EGR which is heavy-handed regarding performance, but really does clean up the air.

The EGR valve simply mixes a little exhaust into the intake manifold. How much depends on the vacuum signal, which comes from a port high on the carburetor. This is not the distributor vacuum advance signal, but rather it requires a signal that does the opposite: gets stronger as the throttle is opened.

Datsun EGR consists of:

• Exhaust manifold with an EGR port tube
• Intake manifold machined to take an EGR body adapter
• EGR passage body, which bolts to the intake manifold
• EGR valve, which bolts to the body
• One or more switches
• Vacuum hoses

EGR parts in red:

For a detailed explanation of EGR, see the AutoZine Technical School article.

VVT =

Venturi Vacuum Transducer is used on later implementations to fine tune how much Recirculation is used. Instead of the crude early systems without VVT, the 1980s implementations use the VVT valve as an amplifier for input signals from backpressure and carburetor signal.

If you run EGR, then VVT is your friend.

Exhaust Manifold

The only modification to the Exhaust Manifold to enable EGR is the casting is changed to add a threaded port to which a tube is fastened. The tube goes up to the EGR Valve.

First EGR (1974) -- tube goes behind manifold

Late A14 style

Early A14 FU style

Vanette Style

Variations consist of:

• Size of the EGR port (diameter of hole and thread size)
• Location. Early engine had it come straight out of the manifold outlet, while newer ones have it pointing almost up

There are also Tube variations: Some tubes are threaded on both ends, others threaded only on the manifold end

Intake Manifold

Intake Manifold has a specially machined flat area where the EGR Body bolts. Nissan calls this adapter body the "EGR passage". In turn, the EGR Control Valve bolts to the body.

1981-1982 H95 EGR (valve not installed)

EGI

A14E and A15E EGI fuel injection engine manifolds use an EGR system.