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And there is no thermo vacuum switch on a 3.0...


You have a '90 model w/o EGR, so there's no thermo vacuum switch - BUT - there is one on the models with EGR. The thermo vacuum switch has 2 vacuum lines that open to supply vacuum to the EGR solenoid valve when the engine is warm. The plastic nipples get brittle and crack with age and heat - sometimes the crack is only partial, yet leaks air like a sieve.

Oh - another thing to check is the purge control solenoid valve operation.

Frank

Last edited by FrankR; 03/29/07 04:23 PM.