How to modify cis warm up regulator?

[Ameer Antar]

I don't think so. If you read about Bosch CIS in the Probst book, the
warm-up regulator controls pressure in the fuel distributor, making it
relatively easier or harder for the piston to move in the fuel metering
head. This controls enrichment during warm-up, ie. changes the mixture. I
think I've heard of people modifying the warm-up regulator before trying to
increase enrich the mixture. I think there's an adjustment screw inside or
under a cap that can be adjusted for engine wear and the like. This is
dangerous b/c it's hard to get back to the right setting, especially w/o
good measuring equipment, like an exhaust analyzer. But it's fine if you
want to experiment, and make reasonable adjustments. The warm-up regulator
works by heating a bi-metal strip which flexes, and changes the pressure
added to the top of the piston in the metering head. The warmer the
regulator, the leaner the mixture. The heat from the block as well as the
internal heater lean out the mixture at a specific rate according the
engine's warm-up needs. I'm not sure what increasing the system pressure
would do as John mentioned. It would probably increase fuel delivery, but
it would put more strain on the system, and the system pressure already is
quite high in the 80-90 psi range. Even though you can do this to
electronic fuel injectors, there is always a limit, and I wouldn't want any
weak link to fail...especially when it comes to fuel...

-Ameer


At 10:00 PM 9/18/2002, you wrote:

>From: "John Larson" <j.d.larson at verizon.net>
>To: <scott at dreamtheater.zzn.com>, <quattro at audifans.com>
>Subject: Re: How to modify cis warm up regulator?
>Date: Wed, 18 Sep 2002 16:52:52 -0700
>
>It's not the CP regulator (AKA "warmup regulator" in layman's terms) you
>want to modify.  It only operates until the engine is warmed up.  You need
>to increase the pressure in the fuel distributor.  The real way is to change
>the shims in the relief valve.  Shims are available in little kits, but I
>haven't seen a kit in years.  You can get some out of old FDs.  There is
>always the option of using a CPR that has a vacuum function to drop the CP,
>but I don't know how that would work with a turbo and it's pressurized
>intake tract.  HTH, John
>
>
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