FW: Bad hesitation, backfiring,and near stalling when cold with a "new" warm-up regulator

[Andrew Pawlisz <apawlisz@emerald.tufts.edu>]

-----Original Message-----
From:	Andrew Pawlisz [SMTP:apawlisz@tufts.edu]
Sent:	Monday, November 09, 1998 09:10 AM
To:	'quattro@coimbra.and.net'
Subject:	Bad hesitation, backfiring, and near stalling when cold with a "new" warm-up regulator

The other day I have replaced a warm-up regulator on a 84 4K and the car runs much worse.  The old unit was inoperative for at least one year, but the car run fine.  Testing of the old unit indicated that there was no resistance between electrical connectors suggesting a burned-out heater of the bi-metallic strip that controls the fuel pressure in the fuel distributor.  The car run rough as if there was a vacuum leak.  I have discovered that by disconnecting the vacuum hose connected to the regulator and plugging it up, I could restore engine's performance (warm).  Went to a junkyard and found one that worked (resistance between connectors).  Slapped it on, and to my disappointment, the car run worse than before.  Although I get a somewhat higher RPM on cold starts (1100; regulator working?) I cannot make the car go without some serious hesitation accompanied by backfiring and the exhaust smelling awful (vacuum leak? wrong air : fuel mixture?).  The problem goes away once the engine warms up.  However, the idle seems rougher now and the engine is not as powerful as before.  What to do?  Should I go back to the old regulator which my car liked (even though it was defective) or should I bite the bullet and fix what is causing the problem (easy fix?).  Winter starts were O.K. last season (thanks to the still operative cold start valve), though the engine lacked power when cold.  

Help please.

Andrew Pawlisz
Medford, MA