Exhaust Gas Recirculation: Testing and Inspection

For California ONLY

- EGR function is monitored via the On- Board Diagnostic feature of the Motronic Engine Control module

- Vacuum lines, hoses and connections must be tight without air leaks

- Do not interchange vacuum lines

- Vacuum lines and hoses must not be linked, bent or pinched

- When checking, engine oil must be at least 50°C (122°F)

EGR valve, checking

- Disconnect yellow vacuum line 1 to the EGR valve from the straight connection on the Thermal Vacuum Valve (TVV) 2 and, connect hand vacuum pump US 8026 (or equivalent) to the removed line

- Start the engine and let idle

- operate hand vacuum pump

- Idle quality must noticeably detenorate

NOTE: If the vacuum drops quickly and the idle quality becomes normal again; the membrane in the EGR valve is leaking and the valve must be replaced.

If NO change in idle quality appears

- Check the Egr or the bores in the exhaust manifold for plugging1 if necessary replace the EGR valve







Vacuum booster, checking

- Connect vacuum tester VAG 1368 between vacuum booster 1 and the red line to the throttle support 2

- Start the engine and let idle

- Measure the vacuum

- must be at least 13 mBar

- Remove the red vacuum line from throttle support 2 to the vacuum tester and seal off

- Connect vacuum pump VAG 139O to the open connection on the vacuum tester

- Activate the vacuum pump until a vacuum of 23 to 27 mBar is indicated on the tester

- The idle quality must be noticeably poorer







- Connect vacuum tester VAG 1368 between vacuum booster 1 and blue line to the Thermal Vacuum Valve (TVV) 2

- Measure the vacuum

- must be between 71 and 101 mBar

- Increase the engine speed to 3100 rpm

- the vacuum must increase to at least 120 mBar

Thermal Vacuum Valve (TVV), checking

- Remove the valve and immerse in a temperature controllable water bath

- Attach a length of hose to the valve to check flow (by blowing into it)

- below 45°C(113°F) = NO flow

- above 61°C (142°F) = must be flow







Vacuum hoses, connecting

1- Throttle body support

2- EGR valve
- for intake manifold

3- Return valve
- for brake booster

4- Plug
- only if connector is available

5- Vacuum booster

6- Thermal Vacuum Valve (TVV)
- only fits one way

7- Connector flange
- to left of cylinder head

Vacuum line color codes:

a = yellow

b = gray

c = blue

d = red