Announcement

Collapse
No announcement yet.

ECU Wiring - patch into factory loom or separate loom?

Collapse
X
Collapse
 
  • Filter
  • Time
  • Show
Clear All
new posts

    ECU Wiring - patch into factory loom or separate loom?

    In the near future im going to need to wire up an aftermarket ECU to the MX5. Now i was originally going to use the stock loom and simply add a few extra wires to it to run additional things. However, as im tallying it up its looking like the additional loom will be almost as large as the stock one and would only take a couple of extra wires to make it a separate loom.

    At the minimum I'll have to add to the stock loom extra wires for sequential ignition and injection (4 wires min), fuel pressure and temp, oil pressure and temp, flex fuel and boost control.

    In addition the stock loom has the air temp sensor on the wrong side of the engine, and has a weird separated loom for the injectors and ignition that ill have to splice into to add the sequential control.

    Starting to think that a standalone engine loom (like on 99% of cars) is the way to go, and just tuck all the stock wiring out of the way. That way i would be patching only a handful of wires into the stock ECU wiring (+12, acc, gnd, and fan).

    Apart from removing all the wiring from the car and unlooming the entire body wiring to pull out the ECU wiring, can anyone think of a better way to do this?
    Chris
    ------
    The new nugget
    I never saw a wild thing sorry for itself. A small bird will drop frozen dead from a bough without ever having felt sorry for itself. - D.H.Lawrence

    #2
    If you've got a decent ECU it will pull the fuel temp from the flex fuel sensor, so no need for an additional fuel temp sensor. If it was me I'd take a stock engine loom and strip it to bare bones so it just contains the factory power feeds etc, then add a long flying loom for your ECU of choice and terminate at the engine side with new plugs/pins

    Comment


      #3
      Originally posted by jasonp1977 View Post
      If you've got a decent ECU it will pull the fuel temp from the flex fuel sensor, so no need for an additional fuel temp sensor. If it was me I'd take a stock engine loom and strip it to bare bones so it just contains the factory power feeds etc, then add a long flying loom for your ECU of choice and terminate at the engine side with new plugs/pins
      This is what i would do if it was almost any other car. But Mazda—in their infinite wisdom—decided to fully integrate the engine and body looms on the MX5.

      In order to strip out the ECU wiring you need to take the entire body loom out of the car:


      Which im just not keen on at all. Plus all the wiring choices are weird, as they run via fuse boxes in random points of the car before going to the engine bay. So the ign and inj wiring goes from the passenger footwell, behind the dash up to the fuse box in the drivers side of the engine bay before running down to the front of the engine and back over the intake manifold after picking up a power feed for it.

      I figure the much easier option is just to add the power feeds i need for INJ and IGN back to the ECU area and then run a separate engine loom out in the normal fashion.

      I think i can ignore some of the stock wiring for alternator, and starter, and reuse one wire from another section for the thermofan switch.

      Looking at the BP engine too, I think there is only one sensor that could be reused (water temp) and one plug that is the same (idle valve). Everything else is either different plugs or new sensors.


      As for the fuel temp, thats only because i was planning on using the Bosch pressure and temperature all in one sensor, but thanks for reminding me that the flex fuel sensor does temp, so I can use one less temp input.
      Chris
      ------
      The new nugget
      I never saw a wild thing sorry for itself. A small bird will drop frozen dead from a bough without ever having felt sorry for itself. - D.H.Lawrence

      Comment

      Working...
      X