[urq] Warm up regulator mod question

n-engelbert at terrans.net n-engelbert at terrans.net
Mon Dec 1 10:09:19 EST 2003

At the shop that I ordered my coolant temp sensor from, I explained my
warmup issues to the owner, and he had this to offer:

Engine is running lean, therefore stumbling and not enough vacuum to raise
airflow plate which is flapping around.  He has lots of experience with old
VW rabbits, etc. and said that they used to mod the warmup regulator a
bit.  Apparently there's a press fit plug in the regulator that rides
against a bimetallic spring that sets the static cold pressure.  The
heating element in the warm up regulator changes the state of this spring
and pressures increase/flows decrease.  They used to press the plug further
into the regulator to reduce cold pressure and improve cold running.

He claims it's something that the vw repair people realized and bosch sort
of knew about.  Instead, bosch wants to sell you a new warm up regulator.

Any validity to this?  I've not done this to my car, though I did replace
some cracked vacuum lines down there yesterday.

Anyway, from my previous post, duty cycles are way off.  With warm engine
O2 connected and temp sensor connected, either 20 or 80% at idle, 21 or 79%
with wot switch closed and idle switch either open or closed.  Tested
yesterday when cold too, steady 80%.  O2 voltage is at a steady .74V.


Nathan Engelbert
83 UrQ 900453

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