Digital WUR plus? ( FrankenCIS )

[Alan L]

Which looks a lot like this; Part No Bosch 0 280 161 007

[JFairman]

Put that part number into a google search and you'll find a whole bunch of them with a wild variety of prices.
Or go wander around in a you pull it salvage yard looking for old CIS Mercedes and see if you can find one there.

[Alan L]

Steve,
If you think it may be useful, I could post it to you for a trial. I suspect it will not solve the pulsing issue though. I don't think the response time of the diaphragm will be able to keep up with the pulses. It was designed to smooth out stepwise CP changes - over a response time of a second or so, not milliseconds.
Regards
Alan

[Reanimotion]

Thanks Gentlemen,
The unit mentioned also appears to have been used on either side of the Frequency Valve in Benz CIS-Lambda installations which are running at the same frequency as our little monster. If my math is right this early in the morning then we are dealing with a 0.0026cc pulse volume at a low-ish frequency of 100hz so on a 1 square cm diaphragm .015mm of movement +- resting point would be all we need to absorb the pulses.

Alan, thanks for the assist! I'll try the smaller units we have here first and will call on your offer if it looks like a larger damper is needed.

copied from the other thread mentioned

Might have some new info in referance to the WUR add on dampener.

In my 91 turbo book it notes they added "capsule valve" to the top of the fuel distributor in order not to retard the over-swing effect during acceleration.

This replaced the fixed orifice in the line to the WUR. This capsule valve opens as soon as the control plunger is lifted by movement of the metering plate during acceleration.

It goes on to say--

"Operation:

When the throttle valve opens, the air energy forces the sensor plate down and control plunger is moved upward. The fuel above the control plunger lifts capsule valve, i.e. flow is not directed past orifice, but is deviated around the valve. Movement of the components is thus not slowed down and metering port can therefore open faster and to a greater degree. The pressure pulse inside the line leading to the line leading to the control pressure regulator is absorbed by the flexible hose connected between fuel distributor and control pressure regulator."

Basically, this lets the metering plate move quicker with acceleration reducing potential for lean condition. Especially between shifts. (Maybe another small reason to keep the de acceleration valve?)

[Alan L]

it p...s me off that UTCIS have my unit (and my money). One or the other would be OK, but both??
I never tried the diaphragm when we were trying to solve the oscillation problem, because UTCIS were keen to solve the issue - rather than patch it up. Which is why my unit ended up going back to them. Since then I haven't been able to get any response.
Alan

[Reanimotion]

Yes, disappointing behaviour for any business, but sadly common.

If the damper works, I'll send you one of our prototype blocks that will at least replace the only bit of the UTCIS worth keeping.

[Reanimotion]

oh, as a status update.

We have others helping with or interested in prototype validation
1. Supercharged Mercedes V8 racer and kit manufacturer here in AU
2. 4cyl turbo application in Germany

I'm off to grab some dampers now

[Alan L]

Steve,
Thanks for the offer.
If you are looking for places to try it out - I'm happy to try it on my track 930. Being in NZ may make it a bit more convenient if you don't find something useful nearby.
Regards
Alan

[Reanimotion]

A busman's holiday!
I could live with that and it would be nice to see green grass again.

[Reanimotion]

Should be testing the revised systems tomorrow
a. EFI damper
b. super secret sneaky alternative

[Alan L]

This all pie in sky theory, but I suspect a spring loaded damper will not work. I just throw this out there, in case it proves right and lots of time is not wasted trying to make something work, where I suspect the principal is flawed. Especially since you have a super secret sneaky option.
For the spring damper to work, it would have to be able to oscillate at the same or better rate as the pulse frequency (and I suspect that is a big ask for a mechanical spring on a damper/diaphragm). What will happen if the oscillations are not exactly in phase with the pulse/CP swings is you will get one phase of oscillation superimposed on the other. At some points they will cancel (smooth out) and at other parts they will add to the amplitude, making the spikes worse.
That is my $0.02c guess at it, and I am happy to be wrong.
Regards
Alan

[WERK I]

Originally Posted by Alan L

This all pie in sky theory, but I suspect a spring loaded damper will not work. I just throw this out there, in case it proves right and lots of time is not wasted trying to make something work, where I suspect the principal is flawed. Especially since you have a super secret sneaky option.
For the spring damper to work, it would have to be able to oscillate at the same or better rate as the pulse frequency (and I suspect that is a big ask for a mechanical spring on a damper/diaphragm). What will happen if the oscillations are not exactly in phase with the pulse/CP swings is you will get one phase of oscillation superimposed on the other. At some points they will cancel (smooth out) and at other parts they will add to the amplitude, making the spikes worse.
That is my $0.02c guess at it, and I am happy to be wrong.
Regards
Alan

Why not just let the experiment play out. We all familiar with the "I told you so" principle.

[Reanimotion]

I must admit I was sceptical too Alan, but the spirit of this silly project began as test and eliminate, so test we did

Now just to make sure of the baseline from last weekend

ran existing setup again and got our ripples


added this little fellow


so we now have

FD -> Sensor -> damper -> wur -> return to tank

and received this nice and happy result



Ok so for the moment the 6 prototype blocks require some massive reworking to integrate a damper, but if you are happy to re-plumb and use something like the bosch unit Alan has in the thread earlier and you can get the pressure sensor upstream then the block is fine or just a bosch frequency valve would do nicely.

Gents - because this is FrankenCIS, I think we have to quote the 1931 movie

Henry Frankenstein: Look! It's moving. It's alive. It's alive... It's alive, it's moving, it's alive, it's alive, it's alive, it's alive, IT'S ALIVE!

.............

Doctor Waldman: You have created a monster, and it will destroy you!

[Reanimotion]

prototype modified to show routing

[Reanimotion]

I'm about to start on the revised drawings for prototype v2 as I'm not comfortable driving around with a mess like the above under the bonnet for further testing.

Are we all happy to keep the production unit within the same footprint as the factory WUR? keeping in mind our thingy is not required for a DIY parts bin build if you are feeling creative.

[Alan L]

That looks very hopeful. What are the intermediate squiggles in your last graph, and presumably the bottom trace is the CP?
Maybe I should have tried my damper with the UT unit - but they were keen to solve the issue in other ways.
My money says keep the WUR footprint if possible.
Personally I don't care how ugly it is if it works better than the UT one.
Good luck.
Regards
Alan

[Reanimotion]

Sqiggles are throttle presses

cleaned up a bit and rescaled for clarity

top
white - RPM
red - Manifold Air Pressure

bottom
white - injector duty cycle
red - target control pressure (flat line through green)
green - actual control pressure

[Reanimotion]

I've currently got it set to quite aggressively counteract the control pressure spikes in the system, this can be tuned down to allow a natural change from the air plate but still allow targeting from the maps

[Alan L]

OK, I may have it a bit wrong here, but why is the CP changing with the throttle blips?
I'm guessing the airplate movement translated thru the fuel head piston is causing a temporary shift in CP? If you hold the throttle open (partially) presumably it will stabilize back to the original CP.
Regards
Alan

[Alan L]

What scale is the CP changing by (in terms of bar/psi) on the throttle blips?
Alan