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Old 03-04-2008, 02:38 PM
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Join Date: Jun 2005
Posts: 20
CIS K Warm-Up Regulator

UnwiredTools Product Announcement:

The UTCIS-V replaces the Bosch Warm-Up Regulator in your Mercedes vehicle. If you have a difficult time starting your car hot or cold, then you may need a new Warm-Up Regulator. A replacement WUR may be very expensive or not available at all. A core-based rebuild would get you back on the road but all WURs wear out eventually and they're difficult to adjust and impossible to adjust precisely. The WUR controls your car's power and fuel economy. If you have to replace it anyway, why not upgrade it?

Finally, there's a modern digital control replacement/upgrade for Bosch CIS K-Jetronic fuel injection. The UTCIS-V replaces the WUR but it does much more. The UTCIS-V is made from precision machined aircraft aluminum which bolts into the stock location of the WUR. A digital controller measures the control pressure and the manifold air pressure and regulates the system. The control pressure isn't just set, it's regulated! Best of all, this digital controller can be programmed with engine control maps to fine tune your power and economy, just like "re-flashing" a new car. The UT Engine Management Software allows you to tune your engine with the click of a mouse. Engine control maps that you edit or create can be shared with others. The UTCIS gives you the benefits of programmable EFI at a tiny fraction of the cost.

You can order this product from Phil.

You can learn more about the product at our website:

UnwiredTools, LLC.

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Old 03-13-2008, 12:55 PM
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Join Date: Jun 2006
Location: Texas
Posts: 18
Will this possibly fix my problem?

I have a 77 350 sl (116984 engine) that races to top rpm at startup. One day I'm driving along just fine and all of a sudden it took off at full power. Ever since then it simply tops out RPMs upon start. Is my WUR broken and will this part correct and enhance my performance?
'77 350SL, Euro-Manual
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Old 03-13-2008, 05:25 PM
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Join Date: Dec 2007
Posts: 59
Sort of..

Our unit will make your car run better but the symptom you describe is not related to the WUR. The UTCIS will not correct this problem.

Does the engine run smoothly when it races? Is the engine power normal when it races, meaning a lot more power than you want? If so then the air/fuel mixture is probably OK. If the mixture preparation is OK that means that whatever is causing the engine to race is due to a unintentional flow of metered air. Metered air is simply air which has passed through the metering plate and your fuel injection has spayed in the proper amount of fuel.

Try the following test:

Remove the air cleaner. Locate the throttle linkage and disconnect the ball fitting from the throttle. The throttle is located under the air metering plate. Make sure the throttle is fully closed. While holding the throttle closed have a helper start the car. Does the engine race on startup? If no then check the throttle linkage. It may also be a bad cruise control amplifier or actuator. Try reconnecting the linkage to the throttle then disconnect the linkage from the cruise control actuator. If you car has cruise control then it's probably the pneumatic type.

If the engine still races on startup with the throttle linkage disconnected and the throttle held fully closed then check the idle air (aux air) bypass valve. This valve is supposed to add additional air when the engine is cold. If this valve turns on when the engine is fully warm the engine RPMs could easily rise to 3000RPM or more. Clamp the air hose with a hemostat or small clamp. If the racing goes away then you've got a bad idle air valve or a bad thermo switch (which controls the valve).
Steve S
Support Tech
UnwiredTools, LLC

1982 380SLC
1994 E320TE
1998 E300DT
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Old 03-23-2008, 06:53 PM
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Join Date: Jun 2007
Location: Just north of Indianapolis, Indiana
Posts: 216
* allenj123, if you haven't already discovered, the cause for your immediate jump to high rpm on start up isn't the warm-up regulator. You've got an air leak in the idle bypass, a vacuum leak, or maybe some jammed throttle linkage.
* The control pressure regulator, also called the warm up regulator, modulates the control pressure, one of the (3) fuel pressures (line, control and rest fuel pressures). This is how the fuel mix is richened for a cold engine, leaned out as the engine warms up, and gives you a little extra fuel on acceleration. When the CPR goes out, you typically get one of two situations; either the engine starts ok cold and won't run right as it warms up OR the engine won't start cold (yet with starting fluid it will briefly run just fine).
* A defective control pressure regulator will never be responsible for the kind of dramatic idle rpm jump you're describing.
ASE Master Tech
Quality Enterprises
Mercedes Svc. & Restoration
Sheridan, IN
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Old 03-25-2008, 05:56 AM
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Join Date: Oct 2004
Location: Marietta, GA
Posts: 3,511
In your tests with the your product, do you see improvements in fuel economy over what the OEM warm up regulator would attain or will the regulator keep the function at a factory optimal state?
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Old 03-26-2008, 01:42 PM
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Join Date: Jun 2005
Posts: 20
Fuel Economy with UTCIS

Yes you have the ability to raise the control pressure, which will lean out your fuel mixture.

We regulate the control pressure, so all other aspects of your fuel delivery system being equal, your mixture will stay consistent and not drift over time as happens with the OEM part when it wears.

A common failure mode of the OEM part is that it fails in the "warm-up/too rich" state, which not only burns excessive amounts of fuel (ie, killing fuel economy), it damages your engine!

We have some screen shots on our website of the Engine Management software in action so you can see how to specify the control pressure, both for the warm up mode and to set the desired "WARM" control pressure.

UnwiredTools, LLC.
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Old 03-27-2008, 01:43 PM
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Join Date: Feb 2008
Posts: 4
Smile CIS-V just installed in 280SE

To see if I could get any more power and better mileage from my old 280SE (1977, with a 110.985 engine - the straight 6 with the older CIS system, with a vaccum connected WUR), I just put one in last weekend.
It took about 2 hours from start to finish, from getting to it from underneath.
the software hookup worked fine. the original settings Unwired tools gave me were OK, but took some tweaking to get the WUR part of the system to work right when cold and when hot. When running you can also set the system pressure, so I set it 1st to 3.6, alittle lean and engine did not have the pep it did. I then changes the setting from 3.5, down to 3.3, at full throttle - the engine seems alot happier. The RPM is staying at 950 after cold start and after running on the highway.
someone up above on on this forum had trouble with the throttle going high. Yep, an air leak would do that. Also, if the air valve thermostat is stuck, the rpm will be real low until it warms up and go high. the air valve is supposed to keep the RPMs high (1100 or so), then start to close as the engine block warms up. At least on my engine. And to get to it is worse than gettting to the WUR.
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Old 03-29-2008, 01:55 AM
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Join Date: May 2001
Location: Northern Va.
Posts: 3,386
I read the installation manual and this device does the same thing as the EHA valve on the later CIS-E system on the W126 cars. May I suggest adding an O2 sensor for feedback?


Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL


Not part of the in-crowd since 1952.
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Old 01-02-2009, 03:30 PM
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Join Date: Dec 2000
Location: South Dakota
Posts: 310
So, after a bit of controversy, what is the latest status of the product and/or opinion regarding upgrading and performance of this product? Is everyone happy now? All the bugs worked out? The investment deserves scrutiny. No snake-oil please.


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