Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: Sigma Engine - Questions About MAP Sensors

  1. #1
    Join Date
    Apr 2019
    Location
    Little Rock, Arkansas
    Posts
    25

    Default Sigma Engine - Questions About MAP Sensors

    I need some advice.

    Some of you may have seen from my build log that my 310S chassis arrived without a MAP sensor installed on the chassis or included in the parts. Not a problem, Josh at RMC has requested one and it is on its way. I would like a little advice about installing it when it arrives.

    1) I know it will be installed on the passenger side foot well. How do I attache it? Do I just drill two holes and use sheet metal screws, or drill two holes and use a nut and bolt arrangement?

    2) What kind and size of hose is used for the vacuum side?

    3) Where precisely does the hose attach to the manifold? I think I have figured that out, but a confirmation, preferably with pictures would be greatly appreciated.

    Don't be afraid of insulting my intelligence. Advice like you would give a 3-year-old and LOTS of pictures are probably the best way for me to understand.

    Thanks in Advance,
    Dave

  2. #2
    Join Date
    Jun 2013
    Location
    N. California
    Posts
    117

    Default

    Dave,
    1) I'd suggest attaching it with 3M Dual Lock. No holes and removable if necessary. It's good stuff!
    2) Whatever size vacuum hose that fits on the barb(s) should work fine.
    3) I'm not familiar with the intake system on your Sigma.

    Andy

  3. #3
    Join Date
    Apr 2019
    Location
    Little Rock, Arkansas
    Posts
    25

    Default

    Andy, Thanks for the suggestion about the 3M Dual Lock. I may give that a try.

    In the meantime, if anyone who has a Sigma under the bonnet could just snap me a picture, it would be greatly appreciated.

    My engine experience is with stove bolt Chevy six-bangers and pre-emissions Triumphs, so anything higher tech than that is a bit mysterious to me.
    Last edited by Squeegee; 07-30-2020 at 06:51 AM.

  4. #4
    Join Date
    Nov 2006
    Location
    Higganum, CT
    Posts
    1,711

    Default

    Quote Originally Posted by Squeegee View Post
    In the meantime, if anyone who has a Sigma under the bonnet could just snap me a picture, it would be greatly appreciated.
    My engine is still in the crate and I couldn't find any pictures on the internet so can't help you there. I would think any port on the intake that is manifold vacuum (after the TB) and fits the hose size of the MAP sensor should work fine. When I get home from work I can check a little closer.
    Bruce

  5. #5
    Join Date
    Apr 2019
    Location
    Little Rock, Arkansas
    Posts
    25

    Default

    Thanks Bruce.

  6. #6
    Join Date
    Mar 2017
    Location
    Western New York, USA
    Posts
    14

    Default

    I have a 310R in the shop and can snap some pictures.

  7. #7
    Join Date
    Apr 2019
    Location
    Colorado Springs, CO
    Posts
    17

    Default

    On the 310S we just built I was advised by Nathan Down to just plug in the MAP sensor and leave the port open to atmospheric pressure. The car seems to run fine and we are at 6,000 feet above sea level so I am equally curious if this is incorrect. Here is a photo of the carName:  20200730_094723.jpg
Views: 59
Size:  45.1 KB
    The sensor is simply stuck to the panel with double sided tape and seems to stay just fine.

    I await the experts to guide me the rest of the way. Cheers,

  8. #8
    Join Date
    Apr 2019
    Location
    Colorado Springs, CO
    Posts
    17

    Default

    Here's another photo for reference:
    Name:  20200730_094751.jpg
Views: 61
Size:  48.1 KB

  9. #9
    Join Date
    Jan 2006
    Location
    Seattle-ish
    Posts
    1,450

    Default

    Dave, is the MAP sensor used as a barometric sensor to adjust for elevation changes, or is it in lieu of a Throttle Position Sensor to feed intake air density information to the ECU for A/F ratios? I B Sevener's setup is the former and why it can be left open to atmosphere.

    -John
    '95 Westfield SEiW w/2.0L Duratec
    '68 Lotus Elan FHC
    '91 Miata w/Flyin Miata suspension & brakes
    '95 Porsche 993 C2
    '86 Porsche 944 turbo (neglected project car)
    Throttle Steer

  10. #10
    Join Date
    Apr 2019
    Location
    Little Rock, Arkansas
    Posts
    25

    Default

    Mark IV, I look forward to seeing the pictures, particularly ones showing the vacuum hose connections..

    IB Sevener, Thanks for the pictures and info. It's starting to look to me like double sided tape or velcro picture hangers may be the easiest way to mount the unit. I am really intrigued that your engine seems to be performing with no connection of the MAP sensor to manifold pressure changes.

    John, My understanding of MAP sensor function rudimentary, to put it mildly. My understanding was that the MAP sensor functions as a constant monitor of air pressure/density in the intake which in turn determines how much oxygen is being fed into the engine. Based upon this, the fuel injection system optimizes the feed fuel to make maximum use of the amount of oxygen available. Like I say, that is just my VERY basic understanding of what the device is designed to accomplish, and I realize I may be completely wrong. BTW, I am at about 350 feet above sea level, so no real compensation for altitude is required.

Posting Permissions

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