Re: Warm-Up Regulator

[steveb@newkla.kla.com (Steven Buchholz)]

>    I was hoping someone could help me with a problem my car has developed 
> recently. My '86 5000CSTQ has been difficult to start for several weeks. 
>  The following was observed:
>
>    4. Where I live it hasn't got too cold yet (50ish) but the cold start 
> valve received no current at any time during cold starts. According to my 
> Bentley, it should receive a pulse, whose time length is temperature 
> dependent, at any temperature under approximately 70 (or is it 80) degrees.

The thermo-time switch and the hot start circuit activate the CS injector.  
It turns out that the circuit that supplies current to the TT switch heater 
also supplies current to the warm-up regulator heater.   

>    6. After several weeks of unsuccesful diagnosis, took the car to a 
> local shop. They claimed the warm-up regulator was bad. This was 
> concluded by them using a pressure test.

You could ask them for the pressure readings that show this.  You plot the
pressure and temperature on a graph that shows the acceptable range.  If you
have access to the Bentley, the graph is in it.  Make sure that the system 
pressure is in spec too.

>    7. My own checks of the warm-up regulator revealed a resistance of 11 
> ohms across the terminals (I believe the manual says 14-22 is OK). I do not 
> have a gauge to check the fuel pressure myself (anyone know where I can 
> get one?). The warm-up regulator was receiving current on start-ups.

I am assuming that you made the measurement with the connector unplugged ...
if not you were measuring the resistance of the TT switch in parallel.  

>    8. Gas was found in the intake air hose leading from the intercooler to 
> the throttle plate. My only guess was that the cold start valve was 
> leaking. Replacement of the cold start valve greatly improved cold 
> starts. The cold start valve is still not working but at least it is not 
> pouring gas into the engine anymore and fouling the plugs.

Unless the engine is backfiring, the CS injector is downstream of the hose 
to which you refer.  The major component that is upstream is the fuel dis-
tributor.  I have noticed on my '88 5kCSTQW that when I push up the throt-
tle plate a drop of gasoline falls on the bottom of the air box ... perhaps 
you have the same problem *in spades*.  I've never seen this problem on any 
of my other similar cars, and I understand that it is not possible to repair 
the FD by simply replacing a seal ... the FD parts are machined to tolerances 
that are supposed to prevent leaks.  I'd recommend that you pull the air fil-
ter and check there.  You may notice gasoline in the hose that leads from 
the airflow sensor to the IC as well ...
>  
> Does anyone know how to check the warm-up regulator?
> The cold start valve is still not working. Does the thermo-time switch 
> located on the underside of the thermostat housing control the cold start 
> valve? Doesn't this control the temp. gauge as well? My temp gauge works. 

The temp gauge sending unit is separate from the TT switch.  I have never 
had to replace a TT switch ... my problems have all been with wiring prob-
lems (i.e. broken).  If the heater circuit for the TT switch opens up the 
TT switch will remain closed for too long, causing the CS Injector to run 
longer than it is supposed to (flooding).  If the switch circuit opens 
then the CS Injector never runs, causing the mixture to be too lean and 
difficult to start.

Checking the warm-up regulator requires the use of a fuel pressure gauge ...

Hope this is of some value to you ...

>       4-wheeled Fleet:                          2-wheeled Fleet
... aha ... we're doing fleets again ... at least they aren't enemas! :0
      '88 5000CSTQW                               '92 BMW k1
      '83 quattro turbo coupe                     '85 Honda CB700SC
      '78 Audi Fox GTI 4+5                            Trek T100 Tandem
                                                      Nishiki Tri-A
                                                      Trek 850
                                               cheapo Miyata mountain bike
**** AND WITH THE EXCEPTION OF THE HONDA THEY ALL FIT IN THE GARAGE! ****
Steve Buchholz
s_buchho@kla.com
San Jose, CA (USA)