Remind me, how does CIS deal with accel enrichment?

[flightlead404]

Remind me

What's the CIS equivalent of an accelerator pump on a carburetor? How does CIS do acceleration enrichment? Is there an equivalent leaning on "tip out"?

Thanks

[gorskined]

Originally Posted by flightlead404

Remind me

What's the CIS equivalent of an accelerator pump on a carburetor? How does CIS do acceleration enrichment? Is there an equivalent leaning on "tip out"?

Thanks

i assume your asking about the warm up regulator for the CIS ? The WUR has a cold setting and a warm setting and a boost setting The wur increases the pressure on the control side of the regulator as the motor and the regulator heats up. its usually at full warm pressure within 5 minutes.
each motor has a specific regulator with a temperature / pressure curve designed for that specific motor .. They now rebuild them and make them adjustable . so you can set the Wur off of your Air fuel ratio (AFR) not sure how carbureted cars do it , but i would be interested to see.
Hope this helps
Thanks

[908/930]

From what I know about CIS it does not have anything, not like a carb where when you move the pedal it squirts fuel. Carbs rely on vacuum to bring fuel in from the float bowl where CIS has fuel pressure and reacts to how much air is moving past the air flow sensor plate.

I should say not all carburetors use accelerator pumps SU carbs and most motorcycle similar to SU don't.

[flightlead404]

Originally Posted by gorskined

i assume your asking about the warm up regulator for the CIS ? The WUR has a cold setting and a warm setting and a boost setting The wur increases the pressure on the control side of the regulator as the motor and the regulator heats up. its usually at full warm pressure within 5 minutes.
each motor has a specific regulator with a temperature / pressure curve designed for that specific motor .. They now rebuild them and make them adjustable . so you can set the Wur off of your Air fuel ratio (AFR) not sure how carbureted cars do it , but i would be interested to see.
Hope this helps
Thanks

No I'm not

I'm talking about acceleration enrichment, adding additional fuel on "tip in"

[Alan L]

The only metering of fuel is via the airplate flap - which is mechanically connected to the metering piston in the FD. There is a cut out waist in the piston and it rises in the FD head as the airplate opens - it gets pushed up against the WUR pressure settings. As it moves up it travels past metering slits in the FD body and the exposed slits allow more fuel thru. Each slit is connected to an injector port.
The only other 'enrichment' dump is when you hit the boost mark. The WUR has an extra port which allows the manifold pressure to connect to the WUR. The pressure depresses the diaphragm in the WUR and softens the WUR pressure. This allows the piston to open more of the metering slits - so you get a boost dump enrichment.
It stays in this richer WUR setting until you return to vac MAP.
It doesn't take full boost for the fuel dump to occur - typically the WUR pressure starts to drop around 0.3 bar MAP.
Regards
Alan

[Mustangkev]

There’s an enrichment relay on the 86-89 930 under the drivers seat next to the k-jetronic box. It looks like it adjusts the frequency valve based on the described in link below.

https://cis911primer.com/pages/descr_lambda.html

[mark houghton]

Originally Posted by Mustangkev

There’s an enrichment relay on the 86-89 930 under the drivers seat next to the k-jetronic box. It looks like it adjusts the frequency valve based on the described in link below.

https://cis911primer.com/pages/descr_lambda.html

Interesting. I always assumed that functioned only as part of the lambda control system as part of the feedback loop from the oxygen sensor.

[mark houghton]

Originally Posted by Alan L

The only metering of fuel is via the airplate flap - which is mechanically connected to the metering piston in the FD. There is a cut out waist in the piston and it rises in the FD head as the airplate opens - it gets pushed up against the WUR pressure settings. As it moves up it travels past metering slits in the FD body and the exposed slits allow more fuel thru. Each slit is connected to an injector port.
The only other 'enrichment' dump is when you hit the boost mark. The WUR has an extra port which allows the manifold pressure to connect to the WUR. The pressure depresses the diaphragm in the WUR and softens the WUR pressure. This allows the piston to open more of the metering slits - so you get a boost dump enrichment.
It stays in this richer WUR setting until you return to vac MAP.
It doesn't take full boost for the fuel dump to occur - typically the WUR pressure starts to drop around 0.3 bar MAP.
Regards
Alan

That's a really good description Alan. Sometimes hard to put all these interlated bits and pieces into words.

[flightlead404]

Originally Posted by Mustangkev

There’s an enrichment relay on the 86-89 930 under the drivers seat next to the k-jetronic box. It looks like it adjusts the frequency valve based on the described in link below.

https://cis911primer.com/pages/descr_lambda.html

That's the bit I was vaguely remembering, but remembering wrong.

For some reason I was thinking there was enrichment for rapid MAP changes, but the article clearly states its for temp and in fact once I re-read that I remembered.

Thanks

A couple of the other posts describe the normal mixture changes based on metered airflow and boost, but don't address acceleration enrichment.

Looks like the K-jet doesn't really do anything for acceleration enrichment.

[908/930]

Are you trying to speed up throttle response? I do not think it is really possible with the stock 930 setup. EFI and individual throttle bodies should do it.

[Alan L]

There is no system like on some carbs with pump jets operating on throttle linkage etc.
Basically it is all a retrospective/reactive system to what goes past the airplate.
And then you wait for the turbo lag to disappear........
Alan

[Alan L]

The K Jet doesn't have an enrichment device other than described above.
However, I believe Andial had an add-on device - which fitted between the FD and WUR.
There was one on my car when purchased. The only way I can see how it worked was to perhaps drop the WUR pressure even further than the dump from the WUR.
Others may have some more info.
Alan

[Reanimotion]

The air plate handles it, by flow response with a bit of overswing.
Mine is setup to log the air plate position.

Yellow trace in the third panel



CARB/EFI tip-in is needed because the throttle opens before fuel can react.
SU/Stromberg carbs and CIS etc. all restrict unmetered air from getting in in the first place, and have the inertia of the metering device to assist with temporary enrichment.

When i was a wee lad, the triple Strombergs on my first car were a pain to keep in tune but heavens they worked well.

[patina]

Originally Posted by Alan L

The K Jet doesn't have an enrichment device other than described above.
However, I believe Andial had an add-on device - which fitted between the FD and WUR.
There was one on my car when purchased. The only way I can see how it worked was to perhaps drop the WUR pressure even further than the dump from the WUR.
Others may have some more info.
Alan

The Andial enrichment device was essentially a 7th fuel injector (they call it a frequency valve) that is plumbed inline between the WUR and the fuel head. It is triggered by a boost pressure switch (set to .75 bar, adjustable) which is installed at the factory overboost switch location. The frequency valve is adjustable via a 6-position hall switch typically mounted on the center console of the car. The first position is “off” and each additional 5 positions offer increases of approx 10% more fuel each. It was a clever solution for the period but the modern RPM controlled solenoid valve paired with an adjustable WUR is much more elegant in design and function.

[Alan L]

Then the thing on my car was a bit different. A bell shaped thing with what looked like an adjustable spring in the bottom and two ports for the FD/WUR fuel line. It has Bosch part # I could dig up some time.
Alan

[flightlead404]

Originally Posted by 908/930

Are you trying to speed up throttle response? I do not think it is really possible with the stock 930 setup. EFI and individual throttle bodies should do it.

No I somehow lost my tune on my FrankenCIS or reverted back to a prior tune or something. Not sure what happened, but now need to correct somethings.

[flightlead404]

Originally Posted by patina

the modern RPM controlled solenoid valve paired with an adjustable WUR is much more elegant in design and function.

Modern? Rube Goldberg is more like it

[908/930]

Originally Posted by flightlead404

No I somehow lost my tune on my FrankenCIS or reverted back to a prior tune or something. Not sure what happened, but now need to correct somethings.

That sucks, do you have your last system and control pressures marked down?

[flightlead404]

Originally Posted by 908/930

That sucks, do you have your last system and control pressures marked down?

I probably did something stupid. I recently switched to a new laptop I think I loaded an old old tune.

Not starting from scratch, and I s/b able to get it dialed back in quickly, but its annoying. Trying to focus on selling my boat lol

[mark houghton]

Originally Posted by patina

The Andial enrichment device was essentially a 7th fuel injector (they call it a frequency valve) that is plumbed inline between the WUR and the fuel head. It is triggered by a boost pressure switch (set to .75 bar, adjustable) which is installed at the factory overboost switch location. The frequency valve is adjustable via a 6-position hall switch typically mounted on the center console of the car. The first position is “off” and each additional 5 positions offer increases of approx 10% more fuel each. It was a clever solution for the period but the modern RPM controlled solenoid valve paired with an adjustable WUR is much more elegant in design and function.

I ran with one of those years ago. A bit rude but it worked