Passat L4-1984cc 2.0L DOHC (1991)
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Connect vacuum test gauges between EGR vacuum amplifier and blue line to EGR thermal vacuum valve (EGR TVV), using the supplied T-piece.
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Start engine and let idle.
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Measure vacuum.
^
must read at least 71 mbar (2.0 in HG) at idle (read right gauge) but NOT MORE than 100 mbar (2.9 in HG)
^
If NOT, replace EGR vacuum amplifier
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After replacing EGR vacuum amplifier, recheck vacuum specifications.
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Turn engine OFF
4.
Check EGR Thermal Vacuum Valve (TVV) function
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Remove hose from yellow line at EGR TVV.
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Connect vacuum test gauges to hose from EGR TVV (yellow line).
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Start engine and let idle.
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Measure vacuum.
^
must read at least 71 mbar (2.0 in HG) (read right gauge)
^
If NOT, replace EGR TVV
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After replacing EGR TVV, recheck vacuum specifications.
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Turn engine OFF
Note
Before proceeding to next step, make certain that all vacuum hoses are correctly routed and securely attached.
G. Check/Replace Engine Control Module
G. Check/replace Engine Control Module
(ECM) (vehicles with manual transmission)