[urq] Warm up regulator mod question

Maurits Jonkergouw urq at moregraphics.nl
Mon Dec 1 10:47:08 EST 2003

Hi Nathan, FWIW, after I cleaned the CPR and replaced the (brown) thermoswitch for the CSV on the back of the head AND fixed a vacuum leak from the intercooler to the IM (the big hose was not seated correctly on the intercooler outlet), it no longer stumbles and the power is back!). I would bet it was the CPR but it was not!

But if you insist: here's a link related to the CPR mod/problem:


PS I noticed _now all isback to normal_, on a cold day, my fuel economy gauge shows 50liter/100km the first minutes and it did not before. What is your gauge reading while it stumbles?

>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
>urq mailing list
>urq at audifans.com


'86 quattro GV (WR)
'85 coupé KV
'82 coupé DD

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