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Old 09-06-2014, 08:16 PM
  Pelican Parts Technical Article Directory    Reply With Quote #101 (permalink)
umop apisdn
 
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locked at 65% duty, I'm tempted to call it and say that an injector in place of the WUR is not the way to go. Still measuring 1.5 bar swing at 100hz due to injector pulses. average pressure may be alright but given the small volume of the control circuit I would guess the system won't last long. This version was intended to verify the last iteration of the UTCIS and given the results could be why they dropped off the map.

bottom section
White = duty cycle
Green = Control Pressure



Should we try for Plan B? I could try increasing the injector frequency but there would still be pulsing. I have an alternative idea that uses a constant flow design but the component cost is higher.
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Steve
1981 928S 4.7 ROW with KE3-Jetronic and Franken8 (AEM Inifinty) follow at [http://www.frankencis.com/Activity-Feed/userid/2]
Yes! mechanical/hydraulic constant flow injection can be managed by a modern EMS

www.FrankenCIS.com
Old 09-06-2014, 09:48 PM
  Pelican Parts Technical Article Directory    Reply With Quote #102 (permalink)
umop apisdn
 
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The up side is it does appear to be working ok, and Bosch used an injector for the frequency valve on the fuel distributor so I may be worrying over nothing.
An analog pressure sensor rather than the digital one may be a better option due to the slower response of physical movement.

I'm just personally not happy with the pressure spikes

below Top
AFR in yellow and varies by 0.1
below Bottom
CP in Green and bouncing with pulses but averaging seems ok by looking at the resulting AFR

Injector firing 100 times a second
Sampling data 10 times a second
idling at around 800 rpm
so about three to four samples per ignition event


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Steve
1981 928S 4.7 ROW with KE3-Jetronic and Franken8 (AEM Inifinty) follow at [http://www.frankencis.com/Activity-Feed/userid/2]
Yes! mechanical/hydraulic constant flow injection can be managed by a modern EMS

www.FrankenCIS.com

Last edited by Reanimotion; 09-06-2014 at 11:17 PM..
Old 09-06-2014, 11:10 PM
  Pelican Parts Technical Article Directory    Reply With Quote #103 (permalink)
umop apisdn
 
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I'm also guessing this might be why UT stopped trying to reference actual control pressure
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Steve
1981 928S 4.7 ROW with KE3-Jetronic and Franken8 (AEM Inifinty) follow at [http://www.frankencis.com/Activity-Feed/userid/2]
Yes! mechanical/hydraulic constant flow injection can be managed by a modern EMS

www.FrankenCIS.com
Old 09-06-2014, 11:20 PM
  Pelican Parts Technical Article Directory    Reply With Quote #104 (permalink)
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This is exactly the problem I had with my injector UTCIS. I spent quite a bit of time with UT trying to rectify it. They wanted a restrictor in the line from the fuel head to the pressure sensor. Their initial conclusion was my fuel head had minimal leakage - less than their bench test model. This may be correct as I had made a new metering piston. Eventually I got down as far as an orifice like 20 thou from memory - would have to check my emails. UT then made some firmware changes, then asked for the unit to be returned. That was a year or more ago. No more progress apparently.
I have some of the tests recorded somewhere if any use.
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 09-07-2014, 01:38 AM
  Pelican Parts Technical Article Directory    Reply With Quote #105 (permalink)
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Thanks Alan,
The restrictor might work but would kill control response speed, an EFI line damper may also help minimise the pulsing but would just be patching a poor design. This prototype based on the Injector was really intended as a baseline as it mimicked a known setup, the result wasn't unexpected, although the magnitude was.

I have two options as I see it to retain the WUR portion of the project.
1. see if we can drive an injector at high frequency to be partially open, thus giving variable constant flow, it's a long shot and dependant on the strength of the internal return spring and opposition to fuel flow.
2. go for plan B which is a block based on the Bosch Differential Pressure Regulator or a bespoke but similar design.

If we abandon the WUR replacement we still have mappable control of the bypass injector for enrichment as per Thierry25's layout.
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Steve
1981 928S 4.7 ROW with KE3-Jetronic and Franken8 (AEM Inifinty) follow at [http://www.frankencis.com/Activity-Feed/userid/2]
Yes! mechanical/hydraulic constant flow injection can be managed by a modern EMS

www.FrankenCIS.com
Old 09-07-2014, 04:18 AM
  Pelican Parts Technical Article Directory    Reply With Quote #106 (permalink)
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IMHO, you're almost there. You've converted a mechanical-analog input to an electro-mechanical digital output. Now all that is left is to convert it back to mechanical analog. What you need is a damper to smooth out all those spike transitions into an average of the transitions.



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'85 930 Factory Special Wishes Flachbau
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Old 09-07-2014, 06:13 AM
  Pelican Parts Technical Article Directory    Reply With Quote #107 (permalink)
umop apisdn
 
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It's worth a try, I'll go fishing in the parts bins and see If we have one
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Steve
1981 928S 4.7 ROW with KE3-Jetronic and Franken8 (AEM Inifinty) follow at [http://www.frankencis.com/Activity-Feed/userid/2]
Yes! mechanical/hydraulic constant flow injection can be managed by a modern EMS

www.FrankenCIS.com
Old 09-07-2014, 06:35 AM
  Pelican Parts Technical Article Directory    Reply With Quote #108 (permalink)
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The pulses are large because you have a high volume injector squirting into a very small internal volume, and it is squirting an incompressible substance. So any teensy weensy change in the volume of liquid in the loop is going to have an instant response. Which is what you want as far as quick response to AFR/boost etc. But not what you want when trying to maintain steady state. putting some sort of damper in there will also dampen the AFR/boost response too. The stepper motor was progressive, so for whatever other faults it had, it avoided this issue.
What you need is an injector system that works progressively rather than by pulse.
Regards
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 09-07-2014, 12:01 PM
  Pelican Parts Technical Article Directory    Reply With Quote #109 (permalink)
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In real life you do have a certain amount of inbuilt damping. I'm not sure quite how you have your test system set up, but the airplate in the CIS responds to these pulses by altering the internal volume.
In my system when things got real bad the pulses sent the airplate into spastic fits trying to follow the pulses. But your trace looks much finer than what I was getting - ie your responses seem much sharper. I will try and find some of my traces (on previous computer I think). from memory UT tried altering the response times (slowing them), but of course this had other consequences. We could get it to sit at a steady state reasonably well, but as soon as a change in CP was required it went into pulses again - this would happen during the warm up phase. It may have asked for say 2.5 bar and it would sit there steady as a rock, then when it asked for 3 bar it would go into spasms.
it seems slightly odd, but UT seemed surprised by the spiking response I had, when I first installed the injector system. I can only assume their bench test system was not doing this. Their conclusion initially was that my fuel head had less leakage (past the metering piston) than theirs. This would have the effect of compensating also, but made the system highly dependant on the fuel head. But it does make me think they had an initial unit that was not spiking so badly, mainly due to the damping effect in the fuel head.
regards
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)

Last edited by Alan L; 09-07-2014 at 12:27 PM..
Old 09-07-2014, 12:21 PM
  Pelican Parts Technical Article Directory    Reply With Quote #110 (permalink)
umop apisdn
 
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I doubt we would be seeing the pulses at all with an analogue pressure sensor. The Oil Pressure sender the other guys were using could not physically move as fast as the change in pressure between pulses, plus the diaphragm and lever setup internally would behave as a small damper.

I can't seem to find an EFI damper in our bits bins, but do have a 996 oil pressure sender we can attach for comparison.
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Steve
1981 928S 4.7 ROW with KE3-Jetronic and Franken8 (AEM Inifinty) follow at [http://www.frankencis.com/Activity-Feed/userid/2]
Yes! mechanical/hydraulic constant flow injection can be managed by a modern EMS

www.FrankenCIS.com
Old 09-07-2014, 04:22 PM
  Pelican Parts Technical Article Directory    Reply With Quote #111 (permalink)
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But I think the injector (and stepper) Digi WUR had analogue pressure sensors too?
The other point is while an appropriate pressure sensor may be able to smooth the pulses out as far as any readout goes, if they still actually exist in the system, they are going to show up at the airplate, which in turn is going to set up a pulsing motion in the CP line.
The best option by far is to find a fuel delivery system that can eliminate the pulsing (IMHO).
You have probably worked it out by now, from memory the UT system was actually using the injector to bleed fuel off to waste (return) rather than injecting fuel in to control CP. (If that helps as a design option).
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 09-07-2014, 04:57 PM
  Pelican Parts Technical Article Directory    Reply With Quote #112 (permalink)
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A constant flow (non-pulsing) solution is the aim, but along the way we want to verify and allow existing solutions and DIY designs to be used if the results are acceptable.
So if a small damping chamber smooths out the CP and still retains 1/10 second control or better the injector version should be retained as an entry level DIY option

The trace below is with 1cc of air introduced to the metering block and it self bleeding over 60 seconds. no other changes
As you can see the CP is quite stable at the left and varying by 4kpa or 0.04 bar, with a good quick response to two throttle blips.
At the right as the air bleeds off we lose the damping and begin the hard swings
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1981 928S 4.7 ROW with KE3-Jetronic and Franken8 (AEM Inifinty) follow at [http://www.frankencis.com/Activity-Feed/userid/2]
Yes! mechanical/hydraulic constant flow injection can be managed by a modern EMS

www.FrankenCIS.com

Last edited by Reanimotion; 09-07-2014 at 05:30 PM..
Old 09-07-2014, 05:26 PM
  Pelican Parts Technical Article Directory    Reply With Quote #113 (permalink)
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Quote:
Originally Posted by Alan L View Post
You have probably worked it out by now, from memory the UT system was actually using the injector to bleed fuel off to waste (return) rather than injecting fuel in to control CP. (If that helps as a design option).
Alan
Yes we mimic the factory WUR by bleeding CP to the tank return. No changes have been made to fuel flow direction or plumbing. Our injector is firing at 100 times per second which equates to about 12,000 RPM In a normal EFI environment.
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Steve
1981 928S 4.7 ROW with KE3-Jetronic and Franken8 (AEM Inifinty) follow at [http://www.frankencis.com/Activity-Feed/userid/2]
Yes! mechanical/hydraulic constant flow injection can be managed by a modern EMS

www.FrankenCIS.com
Old 09-07-2014, 10:21 PM
  Pelican Parts Technical Article Directory    Reply With Quote #114 (permalink)
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Just for giggles, we tried to hold the injector partially open, very extremely sensitive and kept trying to snap shut or open but it held still for nearly 28 seconds




ok back to a pulsation damper or alternative valve type
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Steve
1981 928S 4.7 ROW with KE3-Jetronic and Franken8 (AEM Inifinty) follow at [http://www.frankencis.com/Activity-Feed/userid/2]
Yes! mechanical/hydraulic constant flow injection can be managed by a modern EMS

www.FrankenCIS.com
Old 09-09-2014, 01:22 AM
  Pelican Parts Technical Article Directory    Reply With Quote #115 (permalink)
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Steve,
Is there any way you could fab an old WUR and use the rubber diaphragm that's incorporated in it and temporarily use that as a damper?
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'85 930 Factory Special Wishes Flachbau
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Old 09-09-2014, 04:12 AM
  Pelican Parts Technical Article Directory    Reply With Quote #116 (permalink)
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Hi Dave,
The above test was a bit of coding and easy to do between meetings at the end of work today, plus curiosity got the better of me and I wanted to see if an injector could be controlled while partially open.

I have a few different normal EFI dampers here to try, the setup just needs some plumbing adjustment to get the damper between the injector and the sensor.
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Steve
1981 928S 4.7 ROW with KE3-Jetronic and Franken8 (AEM Inifinty) follow at [http://www.frankencis.com/Activity-Feed/userid/2]
Yes! mechanical/hydraulic constant flow injection can be managed by a modern EMS

www.FrankenCIS.com
Old 09-09-2014, 04:26 AM
  Pelican Parts Technical Article Directory    Reply With Quote #117 (permalink)
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You can buy a metal to rubber control pressure line that goes from the top of the fuel head to the control pressure regulator/WUR from Porsche that has a pressure damper in it.
It smoothed out or dampened the control pressure changes when getting on full boost and closing the throttle and flooring it again so the fuel metering disc under the orifice in the CPR would last longer.
It mounts to the side of the air flow meter housing just below and to the right side of the fuel head. I don't know the part number but I think it's still available and it might be special order.
It has been talked about here before some years ago so maybe a search would find the posts about it. I think the post had the part number in it.
Old 09-09-2014, 09:42 AM
  Pelican Parts Technical Article Directory    Reply With Quote #118 (permalink)
 
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Quote:
Originally Posted by JFairman View Post
You can buy a metal to rubber control pressure line that goes from the top of the fuel head to the control pressure regulator/WUR from Porsche that has a pressure damper in it.
It smoothed out or dampened the control pressure changes when getting on full boost and closing the throttle and flooring it again so the fuel metering disc under the orifice in the CPR would last longer.
It mounts to the side of the air flow meter housing just below and to the right side of the fuel head. I don't know the part number but I think it's still available and it might be special order.
It has been talked about here before some years ago so maybe a search would find the posts about it. I think the post had the part number in it.
Jim, are you referring to this: Control Pressure Dampener from 930SE
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Old 09-09-2014, 11:41 AM
  Pelican Parts Technical Article Directory    Reply With Quote #119 (permalink)
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Yeah, that's it! I don't have one but it's probably a good little gadget for CIS.
I saved the pic of it from that post so we can all see it again.

Old 09-09-2014, 11:55 AM
  Pelican Parts Technical Article Directory    Reply With Quote #120 (permalink)
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