Fourtitude.com - CIS lambda duty cycle staying at 67%
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    1. Member dubsteez79's Avatar
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      Jul 17th, 2014
      Location
      Star, NC
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      369
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      84 GTI, 81 caddy, 55 chevy truck, 74 Beetle, 01 mustang, 70 Corona MK2, 07 Outback, 77 Z28
      03-26-2018 10:11 AM #1
      84 GTI. I just installed a new exhaust and a g grind cam. Adjusted the valves to spec and got the car running decent enough that I feel comfortable driving it and decided to fine tune the fuel system again, as that is the last step before thrashing it in some mountains. When I put my multimeter on the test port, all I can get it to read is 67%. When I swap leads(hoping to see 33%), it still reads 67%. I have unplugged everything(hot and cold) and seen absolutely no change of the test port reading.

      From what I have read and learned over the course of making CIS lambda work initially, the only time it should be at 65%+-2% is when the WOT switch is initiated. My thought is that the wire from the ecu to the WOT switch may be grounding out before it reaches the switch, as it is on its own circuit. Or maybe even internally in the ECU? I dont think it makes sense for the O2 sensor to be causing this but im at a loss for the moment and am open to suggestion. Has anyone else had this issue and resolved it? Thanks in advance.
      Spiral Innovations 336-937-5181
      Contact me for custom metal component needs.
      I offer CNC plasma cutting, sheetmetal fabrication and general design and fabrication services.

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    3. Member dubsteez79's Avatar
      Join Date
      Jul 17th, 2014
      Location
      Star, NC
      Posts
      369
      Cars
      84 GTI, 81 caddy, 55 chevy truck, 74 Beetle, 01 mustang, 70 Corona MK2, 07 Outback, 77 Z28
      03-26-2018 10:42 AM #2
      And I should add that before this, I had gotten everything to spec (~50% duty cycle) and all switches/sensors were working as designed. I was instructed by a trustworthy vw and volvo mechanic who has worked on these things since new(and drives a caddy everyday) to unplug the ecu and plug it back in to see if that changes anything. I will do this and report back to aid in this discussion.
      Spiral Innovations 336-937-5181
      Contact me for custom metal component needs.
      I offer CNC plasma cutting, sheetmetal fabrication and general design and fabrication services.

    4. Member dubsteez79's Avatar
      Join Date
      Jul 17th, 2014
      Location
      Star, NC
      Posts
      369
      Cars
      84 GTI, 81 caddy, 55 chevy truck, 74 Beetle, 01 mustang, 70 Corona MK2, 07 Outback, 77 Z28
      03-26-2018 07:02 PM #3
      I literally unplugged the lambda ecu and plugged it back in and was able to set the duty cycle back to perfect. So just like a PC, just kill power and reset the damn thing any time you have an issue I guess lololol. GTI runs like a champ now!
      Spiral Innovations 336-937-5181
      Contact me for custom metal component needs.
      I offer CNC plasma cutting, sheetmetal fabrication and general design and fabrication services.

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