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    Thread: Odds of TWO CPRs being high!

    1. Member
      Join Date
      Aug 26th, 2005
      Posts
      459
      Vehicles
      1982 Scirocco Callaway Turbo, 1987 16V Scirocco
      10-06-2019 05:45 PM #1
      Doing my pressure tests like a good boy and the warm control pressure was 4.0 Bar.
      Slightly on the high side for a Scirocco which should be between 3.4 to 3.8 bar warm.
      My system pressure was 5.5 Bar which is ok but at the high end of the acceptable range.
      I put in my old CPR and that read 3.95 Bar. Two bad / borderline CPRs?

      My car is a bit off, runs very lean at higher RPM / load so I was thinking high CPR makes things lean
      so that might be the root of the problem.
      I just don't know how sensitive these things are ... is +0.2 Bar enough to throw things off majorly?

      Good CPRs are rather expensive so I don't want to buy yet another one.
      The Dizzy was supposably rebuilt.

      Should I try to lower the system pressure a smidgen?

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    3. 10-07-2019 10:18 AM #2
      How about adjusting the control pressure regulator?

      How common? EVERY regulator I installed while working at the dealership [30 years], the control pressure was tested and adjusted. These are with new ones too. They were not rebuilt back then.

      There are several links out there. I hacked mine and adjusted the pressure that made my POS run pretty darn good in every situation. It's easy to hammer the pin in, but typically it results pushing the pin in too much. The screw trick works great to raise it up a bit.
      http://www.924board.org/viewtopic.php?t=20665

      Always question your gauges. How do you know your gauge is correct?
      Last edited by Butcher; 10-07-2019 at 10:25 AM.

    4. Member
      Join Date
      Aug 26th, 2005
      Posts
      459
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      1982 Scirocco Callaway Turbo, 1987 16V Scirocco
      10-07-2019 03:17 PM #3
      Quote Originally Posted by Butcher View Post
      How about adjusting the control pressure regulator?

      How common? EVERY regulator I installed while working at the dealership [30 years], the control pressure was tested and adjusted. These are with new ones too. They were not rebuilt back then.

      There are several links out there. I hacked mine and adjusted the pressure that made my POS run pretty darn good in every situation. It's easy to hammer the pin in, but typically it results pushing the pin in too much. The screw trick works great to raise it up a bit.
      http://www.924board.org/viewtopic.php?t=20665

      Always question your gauges. How do you know your gauge is correct?
      Well ... how would I check my gauge?
      I bought it new but that was over a decade ago.


      I've toyed with getting the UTCIS-V programable WUR but its $$$
      Plus I'm not 100 percent sure the WUR is causing a serious issue ... its just slightly high control pressure which would lean things out a bit.
      The 924 stuff looks VERY interesting but man I don't want this to turn into another project!

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    6. 10-08-2019 10:26 AM #4
      I was a Shop Foreman for most of my carrier while working at a dealership [30 years and 24 as a Foreman]. I had one guy [Mike, he was an idiot] that was having issues diagnosing some electrical item. I do not recall what system but nothing was making sense. After several hours I suggested that he use another DVOM and low and behold, the values on his meter were wrong. Mike spent hours wasting his time trusting his tool. He replaced the battery in his Fluke meter and low and behold, the meter was now working properly. The next shop meeting I had, I handed out batteries to every mechanic and told them to replace their battery in their Fluke meter. I've only seen this twice in 30 years.

      Do you know how many mechanics trust the fuel gauge only to find out the engine is not running because the gauge reads half and it's really empty? It's embarrassing to work on a car for hours only to find out it's out of gas.

      So, I have always remembered Mike's story when I diagnose something that is not going right. That is why I asked if your gauge is reading correctly. New does not mean it's good. I do not know how to check it unless you compared it to another gauge. If two of them are reading the same, then the odds are that they are good [vs having two bad gauges]. This also applies to engine over heating. Most rely on the factory gauges and they are not that reliable as they get older.

      Making your control pressure regulator adjustable, allows you to tweak the system so it works for you. The specs are a good base line but sometimes tweaking them does wonders. That applies to the system pressure too. With both being adjustable, you can always set them back up to specs if things are not going your way.`

      As for the UTCIS-V version, I called awhile back and even with a shop discount, it's not that cheap.

    7. Member
      Join Date
      Aug 26th, 2005
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      459
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      1982 Scirocco Callaway Turbo, 1987 16V Scirocco
      10-08-2019 04:57 PM #5
      Gotcha ... if it gets too weird I might have to start suspecting the gauge.

      I've read a lot about WUR modification on vortex.
      I noticed that the one I got that was rebuilt (very nicely) has what looks like little drift marks in the circular depression on the outside front.
      The one that's on the other side of the "adjustment pin" / thing the bi-metalic spring bolts to.
      So perhaps someone "fine tuned" this one at some point ... perhaps not quite right or maybe they drift or change over time.
      I guess you tap on that to lower the pressure.

      The "fully" adjustable modification is something I'd like to do ... might toss it to a machine shop.

    8. 10-09-2019 11:12 AM #6
      If you can drill and tap a hole, then you could make it adjustable yourself.

      Just drill a hole in the adjusting pin. Tap it to the size bolt you want to screw into it. Then screw the bolt [with a nut attached] to the pin. You can press the pin in by hitting the bolt with a hammer. If you go too far, use the nut you put on the bolt to pull the pin up. How far do you drill the hole? I do not recall. It's easy to pull the back cover off the regulator to see what you are working with. I've only done it once and I suspect it was about 10-13mm deep. Please do not use my recommendation because I cannot recall exactly and I do not want you to drill all the way thru.

      If you look at ones that has been modded, you will see what I'm talking about. Basically you just want to fine tune the pressures for your set up. Specs are used as a guide. Specs will allow the engine to run good. Sometimes tweaking the pressures beyond specs will make it run great.

      When they design cars, they have to run as cold as the North Pole and as hot a Death Valley. I'm certain you do not have those extremes so you can fine tune it to your liking.

    9. Member
      Join Date
      Aug 26th, 2005
      Posts
      459
      Vehicles
      1982 Scirocco Callaway Turbo, 1987 16V Scirocco
      10-13-2019 09:39 PM #7
      Ok ... I kinda get this now.

      Well, I did a Jeremy Clarkson and used my mighty hammer to punch the plug in a little.
      Dropped the pressure to 3.0 Bar warm ... a little low now. I can see the desirability of making this adjustable.

      I don't have a drill press, might mail it to a friend who has a machine shop and have it done up right.

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