VWVortex.com - Rebuilding a CPR and adding adjustability
Username or Email Address
Do you already have an account?
Forgot your password?
  • Log in or Sign up

    VWVortex


    Results 1 to 23 of 23

    Thread: Rebuilding a CPR and adding adjustability

    1. Member
      Join Date
      Apr 22nd, 2002
      Location
      NJ 08002
      Posts
      4,949
      Vehicles
      2 clunkers & 2 nicer clunkers
      11-20-2009 12:36 AM #1
      OK, this thread was initiated, because of this thread... http://forums.vwvortex.com/zer...71900
      As stated, I decided to rebuild and add (easy) adjustability to the cold control pressure. This wasn't my design, I got it from here: http://www.pelicanparts.com/te...g.htm
      1st step, remove the screws and be careful when removing the bottom cover. It's under spring tension. This is what you'll be looking at. The spring, hat and pin have been removed, exposing the entire heating element. I've had heating elements that read 12 ohms and were fine. IIRC, Bentley call for 16-22ohms? As long as you're not open, I'd use it.



      Remove the horseshoe clip holding the electrical connection, then the 10mm nut and washers. The threaded stud/plug (to the right) sets "Cold Control Pressure". The blackish cylinder (to the left) houses a diaphragm that controls both "Cold & Warm Control Pressure".


      I removed the 4 screws while the cylinder was still in the housing. I got ahead of myself and should have pressed it out (don't hammer) first, with a vice or press, then removed the screws.
      Once the lower cover is off remove the steel diaphragm. If it's sticking, loosen it with carb cleaner and compressed air. Like a jackass I scratched my diaphragm, because it was stuck and I picked at it with a small screwdriver. It wasn't a fatal scratch, so all is good. This diaphragm is thinner than a piece of paper, so be careful.



      Here's the o-ring and rust that was under the diaphragm.



      I mentioned I sprayed carb cleaner at the supposedly clean looking screens, and blew it out with compressed air. I couldn't blow air through it with my mouth, so I pulled the 5 screens. and a lot more rust was hiding under them. Air went through, effortlessly.



      Prior to cleaning parts. Don't look at the scratched diaphragm.



      Reinstall the plug, flush with the top housing using a little antisieze. Use a drill press and drill the 1.5mm roll/tension pin hole first, then tap the pin in. Next, centerpunch, drill then tap the hole for the 5mm bolt. If you're not 100% centered, that's fine.... get it as close as humanly possible.
      A roll pin assortment is available in a small Dorman blisterpack for about $3, in the "Help" isle of auto stores. There's only (1) 1.5mm pin in it. In my pic, I used the next size up, as I've made these in the past. Just tap it until it just peeks through the bottom, then cut and file off the excess.



      Start reassembly; anything that had grease was regreased with synthetic. For the "cold" plug, tap the plug about 2-3mm deeper than it originally was. Press the blackish cylinder back in (using a little antisieze), leaving it 1-2mm higher than it originally was. Large port is to the right when "in position".



      Bottom out bolt with washer and nut and you're done.



      Setting pressures...
      Reinstall fuel lines, but keep the plug disconnected and don't bolt the CPR to the block. At this point, have the CIS gauge hooked up. Pull the injectors, jump the FP relay and set the sensor plate height. Reinstall the injectors, and start the car. Remember that lower control pressure is richer.
      Now if you tapped the plug lower than it was, the cold control pressure should be very low. Turn the nut clockwise, so it's pulling the plug out. 20-25 psi is what I aim for, depending on ambient temperature. Mine was set to 21 psi @ about 55*F.
      If the pressure is higher than your goal, tap the plug in. Make sure the nut isn't bottomed out, place the CPR on something solid and give it a whack. I use the intake manifold for stability and start with light blows. While watching the gauge, you'll get a feel with how much force to use and this plug requires some.
      Once the pressure is within spec, plug the CPR in. Your harness should have a steady 12v. I waited until the fan ran twice, but didn't need to. After a minute, the pressure will have crept as high as it will, as it's working off the internal heating element. Mine pegged at 40 psi. Now, what a lot of people don't know, is that the "warm" pressure is also adjustable. I stumbled upon this in a MB forum.
      Since you left the cylinder higher, your warm control pressure should be lower (richer) than ideal. Using a flat tipped drift, tap the cylinder down. Do not tap the banjos, and do not use a lot of force. I've damaged a cylinder (in the past) and this plug doesn't require a lot of movement for significant changes.
      This is the only safe place to tap the cylinder.....



      .... to get this.



      Originally, I accidentally overtapped to 60 psi, disassembled, reassembled, then set it to 54 psi. Because of this, I wanted to verify my cold setting, and saw 40 psi. My point being, if you reopen it, reverify both settings. I've verified both settings 3 times since hooking this up.
      I ended up resetting my warm pressure to 52 psi. The range you want to be in is 49-55 psi, so I wanted to be in the middle. For a modified engine, I'd want to be at 49 psi or lower. All of this disassembly has me thinking of making a version "2" with easier cold and adjustable warm settings.
      In the end, I saw 21 psi cold, 52 psi warm with a 45* dwell +/- .2* @ 900rpm. My cold idle sucks, because I need to address my auxiliary air valve. I'm only really concerned about warm idle anyhow.
      -Todd


    2. Member T3Bunny's Avatar
      Join Date
      Mar 30th, 2005
      Posts
      2,154
      Vehicles
      1977 VW Rabbit
      11-20-2009 02:01 AM #2
      This is an amazing write up! It needs to be added to the FAQ's section!

    3. Member CodeMan's Avatar
      Join Date
      May 12th, 2006
      Location
      Westminster, CO
      Posts
      8,015
      Vehicles
      Scirocco 16v, E34 540i, V50 T5 AWD
      11-20-2009 09:54 AM #3
      I love your threads.
      The blues ain't nothin' but a good man feelin' bad.

      Tschüß Gilda, Hallo Birgit

    4. Member Conejo Negro's Avatar
      Join Date
      Apr 2nd, 2007
      Location
      Yonkers Ny
      Posts
      729
      Vehicles
      76 Rabbit 81 Caddy 72 BMW 2002 91 BMW 535i
      11-20-2009 10:09 AM #4
      Awesome man. [IMG]http://*****************.com/smile/emthup.gif[/IMG]
      Had this on deck for this weekend. [IMG]http://*****************.com/smile/emthup.gif[/IMG]

    5. 11-20-2009 10:13 AM #5
      Cool stuff.

    6. Senior Member vdubspeed's Avatar
      Join Date
      Jul 18th, 2002
      Location
      Valdosta, GA
      Posts
      20,935
      Vehicles
      I quit counting.
      11-20-2009 10:33 AM #6
      very nice [IMG]http://*****************.com/smile/emthup.gif[/IMG]
      Built > Bought
      58 Beetle | 79 Rabbit 20vT | 84 GTI TDI |84 GTI 16vT |12 Golf TDI ----89 325i | 99 QCSB Ram Cummins | 02 Burb 4x4 2500

    7. Member backinthegame's Avatar
      Join Date
      Dec 13th, 2004
      Location
      Virginia Beach, VA
      Posts
      4,556
      Vehicles
      89 Cabriolet, 90 Corrado, 83 Caddy, 87 GTI, 07 A6 Avant,2012 powerwheels Jeep
      11-20-2009 10:43 AM #7
      Quote, originally posted by T3Bunny »
      This is an amazing write up! It needs to be added to the FAQ's section!
      Sent from my Droid using an escape pod to Tattoine.


      Quote Originally Posted by mad8vskillz View Post
      they're trying to skip out on their contracts via rapture. not very christian of them

    8. Member
      Join Date
      Apr 22nd, 2002
      Location
      NJ 08002
      Posts
      4,949
      Vehicles
      2 clunkers & 2 nicer clunkers
      11-20-2009 11:08 AM #8
      Thanks guys.... I've got a ton more projects that are half finished, but I try and post when time allows.
      While searching the archives, I recall someone who wired in a variable resistor that was dash controlled. By limiting the voltage to the heating element, he was able to control the warm control pressure. He raced, so this wouldn't apply to me, but I thought it was cool.
      BTW, I've rebuilt these in the past, too.



      Slightly more involved, because of more parts, but definitely doable.
      -Todd

    9. Member Conejo Negro's Avatar
      Join Date
      Apr 2nd, 2007
      Location
      Yonkers Ny
      Posts
      729
      Vehicles
      76 Rabbit 81 Caddy 72 BMW 2002 91 BMW 535i
      11-20-2009 11:55 AM #9
      Did you leave the CPR with no mesh or did you reinstall the old ones?

      I would love you long time if you post up a fuel dizzy guide like this one [IMG]http://*****************.com/smile/emthup.gif[/IMG] [IMG]http://*****************.com/smile/emthup.gif[/IMG]


      Modified by Conejo Negro at 9:01 AM 11-20-2009

    10. Member Holden McNeil's Avatar
      Join Date
      Jul 26th, 2004
      Location
      Hennepin Co, Minnesota
      Posts
      11,345
      Vehicles
      2013 Fiat 500 Turbo
      11-20-2009 12:10 PM #10
      Fantastic write-up!! Many thanks!!!

    11. Member
      Join Date
      Apr 22nd, 2002
      Location
      NJ 08002
      Posts
      4,949
      Vehicles
      2 clunkers & 2 nicer clunkers
      11-20-2009 12:25 PM #11
      My screens were fubar & I left them out.
      I guess you could find suitable replacement material, but since the clog lied under and between the screens, leaving them out ensures it'll never happen again.
      If you drive the car and keep fresh gas in it, I doubt it'll ever be an issue. Mine looked like rust from moisture in the fuel and sitting stagnant.
      There are a bunch of write ups for the FD rebuild. Googling it will take you to Porsche or MB forums (with active pics) where CIS is common. It won't look exactly the same, but functionally, it is. Take your time with this, if you attempt it. There are a lot of o-rings that can be torn if you start forcing stuff, due to the very close tolerances.
      -Todd

    12. Member
      Join Date
      Apr 22nd, 2002
      Location
      NJ 08002
      Posts
      4,949
      Vehicles
      2 clunkers & 2 nicer clunkers
      11-20-2009 08:56 PM #12
      Adding some pics. I don't like editing 1st posts; some people may miss the updates.
      Missing pic of what you'll see when you first remove the lower cover.



      echassin, posted pics of his CPR disassembled. It's a different style that I had shown, so I went into the garage and opened both styles.
      Other than the obvious taller height of the one he had, the bottom plates are different. The inside of his bottom plate houses a brass disc. Smooth on the outside, and ribbed like the bottom of a tin can, on the inside. Other noticeable differences were a shorter spring, and different hat design with an integral and removable pin.



      Opening them will reveal 2 different heater elements.



      The dual element in his seems to be designed to work in opposing forces, hence the dual elements and pins. It would make sense that the elements travel less. There's the good possibility that the warm control pressure could be adjusted by tapping the brass plate. I'd still feel safer tapping the black cylinder.
      Here's another reason your warm pressure may be out of spec. Pressing one cylinder out was insanely difficult. I had to grab a torch and some penetrating oil, due to internal corrosion.
      Inside the cylinder's fuel chamber was (amazingly,) spotlessly clean, including above and below the screens. Here's the bad part.... the lower plate and the small disc the pin rests in, were rusted together. The smaller disc is pressed by the pin and moves against the steel diaphragm. If the diaphragm doesn't move, pressure doesn't change. Antiseize these parts.



      Also, break the 4 small screws on the fuel cylinder, prior to pressing it out. They're pretty tight and it's hard to hold the cylinder and break the screws free. I ended up pressing it back in, so I could lock the body in the vice.

      -Todd

    13. Member
      Join Date
      Aug 4th, 2000
      Location
      Kailua, HI
      Posts
      13,145
      Vehicles
      MK1 GTI, '95 Golf 2.0T
      11-21-2009 01:26 AM #13
      Thank your sir. I need to do this soon.

    14. Member 2mAn's Avatar
      Join Date
      Oct 15th, 2006
      Location
      Culver City
      Posts
      6,878
      Vehicles
      changes daily...
      12-23-2009 04:03 PM #14
      this DEF should be in the FAQ

    15. Member BoraVR's Avatar
      Join Date
      Mar 13th, 2005
      Location
      Toronto
      Posts
      1,912
      Vehicles
      '87 MK1 Cabby, '08 B6 Passat
      12-23-2009 05:03 PM #15
      wow, thank you for a great write-up!
      Mk1 Mayhem
      ______________

      VRSociety #142

    16. Member alec stensaa's Avatar
      Join Date
      Jan 9th, 2008
      Location
      Stanwood WA
      Posts
      415
      Vehicles
      1983 vw rabbit
      01-20-2012 02:33 AM #16
      Just so every one knows you don't need to do this to enrich the fuel. all you meed to do is tap the pin down.


    17. Member funpig's Avatar
      Join Date
      Feb 13th, 2003
      Location
      Decatur GA
      Posts
      740
      Vehicles
      69 Austin Mini Panel Van, 81 Caddy, 83 GTI, 11 JCW Clubman
      11-28-2012 08:25 AM #17
      Subscribed

    18. Member A1peopleS2wagons's Avatar
      Join Date
      Dec 1st, 2010
      Location
      AZ.
      Posts
      1,599
      Vehicles
      85 legend turbo,76 Chevy silverado
      06-19-2013 09:50 PM #18
      Quote Originally Posted by Holden McNeil View Post
      Fantastic write-up!! Many thanks!!!
      I can't put it in better words.
      http://website.lineone.net/~dr.dub/
      Wenn kein scirocco es ist nicht Scheiße!
      "SO $1000 PLUS FOR 5 HOURS WORTH OF WORK....IN A MK1 OR MK2 YOU CAN HAVE THE ENGINE OUT AND APART IN 4 HOURS IF YOU'RE DRINKING BEER AND SMOKING POT AND CHASING THE WRENCH FOX AROUND THE GARAGE."uncle hal

    19. Member
      Join Date
      May 12th, 2012
      Location
      Steamboat Springs
      Posts
      1,097
      Vehicles
      1984 GTI, 2003 GTI 20th
      06-22-2013 03:18 PM #19
      this is interesting, they have the version with 2 heating elements. On the back of the cpr they drill a hole thru the brass disc to reveal a allen head socket that is used instead of tapping the big plug in...

      edit: after watching the video again and looking at my spare cpr, the cpr in the vid is different than the 2 shown in this thread

      Last edited by Gromel; 06-22-2013 at 03:32 PM.

    20. Member rabbitnothopper's Avatar
      Join Date
      Oct 19th, 2009
      Location
      D-Town REPRESENT : Texas
      Posts
      10,333
      Vehicles
      RIP81. 78 VW Rabbit 1.5L EH 4speed 020 GC->GP, 82 Rabbit Pickup 1.6D
      06-24-2013 10:15 PM #20
      just did this with my orig 78 wur/cpr

      many drill bits are SAE sizes
      the best fitting final bit (size up from small to larger) was a 11/64inch

      7/64 to 9/64 to 11/64 worked great

      used a M5x.80 tap


      my screens arent too terribly rusty or anything
      youre saying there are 5 pressed screens in there?!

      yep 5 screens
      3 different mesh sizes
      apparently sandwiched largest outside smallest in the middle
      the smallest one was very hard to see through


      i can finish rebuilding this one in the next few days
      then install it and test it
      Last edited by rabbitnothopper; 06-26-2013 at 10:25 PM.

    21. Member
      Join Date
      May 14th, 2005
      Location
      Medicine Hat, AB, Canada
      Posts
      454
      Vehicles
      1992 Syncro Wagon, 1992 Syncro Sedan, 1971 GMC Suburban 2wd, 2014 Tig 6sp
      01-17-2016 11:17 PM #21
      Sorry for bumping an old thread. Which way do you press the cylinder to remove it?

    22. Member
      Join Date
      Apr 22nd, 2002
      Location
      NJ 08002
      Posts
      4,949
      Vehicles
      2 clunkers & 2 nicer clunkers
      01-18-2016 02:55 AM #22
      Surprised to see this one surface. Been out of the gas world for at least 5 years.

      Been a while, but I think I pressed the plug inward, using a vice. Used a socket as a press arbor.

      -Todd

    23. Member
      Join Date
      May 14th, 2005
      Location
      Medicine Hat, AB, Canada
      Posts
      454
      Vehicles
      1992 Syncro Wagon, 1992 Syncro Sedan, 1971 GMC Suburban 2wd, 2014 Tig 6sp
      01-18-2016 12:46 PM #23
      Thanks Todd.

    For advertising information click HERE

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •