# Can I swap a CIS-E (motronic) fuel dizzy for a CIS-Lamba fuel dizzy?



## atlanticcoastcustoms (Sep 26, 2007)

I have been having corrosion problems in my 'rocco (whats new), and have been clogging fuel distributors and WUR's for a while now. I picked up an aluminum fuel distributor from the yard out of a '91 16V Passat. My thought process at the time was:
Newer, better constructed distributor might have less internal corrosion because its aluminum, and I could effectively eliminate the WUR while I'm at it, also reducing the points of clogging. 


*I should mention that I intend to replace the tank, when that becomes an option, right now im just trying to simplify my every-other-month rebuilds. 

Question is:
Can I run the FPR from this '91 16V, CIS-E Motronic as well as the built-in DPR, in place of the WUR and Frequency Valve from my stock CIS Lambda setup?

I'm curious if there is something I'm missing.
From reading diagrams, it seems to me that this would work. I'm not beyond giving it a test-run to see. I also plan to swap in the fuel pump, accumulator, and primary filter setup from the Passat as well, just on the grounds that they are in good shape, and were holding pressure when I pulled them. 

Any ideas?

Waste of time?


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## ArsenicPants (Apr 6, 2008)

you would need the Motronic computer as well, so it knows what the do with those extra sensors
but in all honestly, Lambda is a better system than CIS-E, I would try and find the proper fuel distributor & metering plate


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## atlanticcoastcustoms (Sep 26, 2007)

Thanks for the reply, but unless I'm misunderstanding something, the computer should be providing the same signal to (what would be the Frequency Valve) the DPR, as all it does is interpret a signal from the 02 sensor. For that matter, it can even be shorted to run WOT mode, if need be.
As for the FPR, that is a vacuum controlled device, and has nothing to do with the computer. It is a stand-alone unit. The WUR (which it is essentially replacing) is also not controlled by the computer, per-se- it just receives voltage for a warming circuit when the temp is cold out, otherwise it is controlled by the temperature of the engine block.

I'm aware of the benefits of the simpler CIS system, I would never switch to Motronic, that's not at all what I was suggesting. I am rebuilding the steel distributors and cleaning frequency valves and WUR's all the time as is, *until I find a new tank. 

The only reason I am switching to the aluminum Motronic-style distributor, is to possibly eliminate the WUR, and to keep down the corrosion.


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## WaterWheels (Aug 14, 2005)

atlanticcoastcustoms said:


> . . . but unless I'm misunderstanding something, the computer should be providing the same signal to (what would be the Frequency Valve) the DPR, as all it does is interpret a signal from the 02 sensor. . . As for the FPR, that is a vacuum controlled device, and has nothing to do with the computer. . . The WUR (which it is essentially replacing) . . . I'm aware of the benefits of the simpler CIS system, I would never switch to Motronic, that's not at all what I was suggesting. The only reason I am switching to the aluminum Motronic-style distributor, is to possibly eliminate the WUR . . .


Yes, you seem to be misunderstanding a few things in your quest. The Motronic ECU does not send the same information to the DPR as the Lambda control box does to the frequency valve. The frequency valve functions as an on/off (duty cycle) valve and it only receives commands to open and close. The Motronic ECU sends a constant electric current to the DPR which varies in strength to move the tiny valve inside, but not just open and close. So even though there is much that is different, that part alone will not jive.

The fuel pressure regulator is not operated via vacuum. It is a pure spring/diaphram set-up and requires no vacuum. The small hose attached just runs into the air filter box for atmospheric pressure (and to allow access to an adjustment screw). It also does not do the same function as the control pressure regulator (old name WUR). The WUR varies the pressure on top of the fuel distributor plunger to adjust the mixture as required. When cold it allows the plunger to lift higher and provide the needed fuel enrichment. When warm it raises the pressure on the plunger to what you could say is the normal running mixture.

I can't think of anything you could really call a benefit from staying with basic CIS or CIS w/Lambda, but that I guess is another topic. The fuel distributors themselves are different internally and work different so the swap will not work in either case. If newer or aluminum is your goal, get a rebuilt unit, should be good for many years, or find a VW Motorsport unit. The basic and Lambda CIS systems need the WUR so you can't just delete it, but you can buy an electrical programable one for about $400 (maybe less?). To be honest, I would do the complete changeover to either CIS-e or Motronic, maybe even an EFI system.


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## atlanticcoastcustoms (Sep 26, 2007)

Thanks for the info. 
Its a bummer to hear that I can't eliminate the WUR, that seems, so far- to be the bulk of my problems. I was really just looking for a more rebuildable, less corrosion-prone option. 
Guess this isn't the way to go.
thanks for the help!


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