85-86.5 MY Fuel Injection Harness Project

[928drvr86.5]

Last spring while doing the intake R&R on my 86.5 928 I came to realize that my fuel injection harness was in dire need of repair if not total replacement. Due to the somewhat cramped 928 engine bay and 21 years of heat cycling the harnesses' outer vinyl sheathing, and in some cases the insulation on the wires inside had become brittle and crumbled when disturbed. As part of the intake R&R I did some make-shift repairs to the compromised areas of the harness so it would last the summer. I did these shrinktubing based repairs with the intent to completely replace the harness with one of my own design during the winter downtime.

The next few pictures document what has been accomplished so far with the harness and also include drawings of some of the factory color coding for the various sensors, injectors, MAF, etc. When i started this project i believed that i could design and produce a harness that is not only superior in construction and servicability to the available OEM harness, but would also cost significantly less. With that in mind I have designed a harness that utilizes a corrugated split loom construction with a continuous heat rating of 250F and a short term rating of 300F. As the project progresses i will update this thread with new information and eventually document the finished project and it's installation to my 928. Eventually i plan to market these harnesses to the 928 community, in my opinion it is a critical item that is in desperate need of replacement in alot of these older 928s. I plan to offer just the 85-86.5, US MY, 32V harnesses at this point, with additional MY's added as time and resources permit.

Many of the details of the harness have been ironed out at this point and here is where things stand:

I will need to require core harnesses so that i can harvest certain materials that are no longer available or are not cost effective to replace if the originals are in servicable condition. All of these items except one come from the harness on the cabin side of the firewall so they should, and NEED TO be in good/servicable shape. These items include:

• The two 25 pin AMP connectors at the EZF & LH brains

• The green & white 1mm gage wires and two pin connector that feed the ignition triggers

• The oxygen sensor's green 1mm signal wire/plug and two pin connector

• The Central Electrical Panel, "W" connector.

• The idle adjustment, "TEST" connector from the front of the intake.

The specific details of the harness are as follows:

• All wires between the LH-EZF plugs, Injectors, Sensors, and W plug will be replaced and upgraded from .75mm to 1mm in the factory correct DIN color coding

• Every harness plug, wire, and ground ring terminal will be new on the engine side of the firewall except the test connector

• The harness loom will be constructed of Harnessflex corrugated split loom and associated T,Y, and elbow fittings with a 250 deg. F. continous duty, 300 deg. F short term rating

• To facilitate ease of installation (and removal) a 31 removable pin Deutsch plug/socket connector will be utilized where the harness passes thru the firewall.

• All wires running to the connectors on the engine side of the harness will be protected with high temp fiberglass sleeving where they break away from the main harness.

• All Amp 2, 3, 6, and the 25 pin brain connectors will utilize new pins that will be crimped and then soldered.

And finally, i can offer these harnesses for $850, a $250 savings on the cost of a new OEM harness.

Production of these harnesses is still a few months off due to a revision in design of the prototype harness that necessitated an additional order of split conduit loom and the associated fittings. Once the prototype harness is complete and sucessfully installed in my 928 i will order additional materials to construct harnesses to sell to the community. A thread on this topic has also been posted on the R-list forum.

Ben

[928drvr86.5]

This picture of the harness has already been posted, but it is still pretty much the same right now as i am awaiting additional parts to complete it.

[928drvr86.5]

The wire color coding for the MAF

[928drvr86.5]

Temp I

[928drvr86.5]

Temp II

[928drvr86.5]

The fuel injectors

[928drvr86.5]

color coding for the LH and EZF brains.

[928drvr86.5]

The pin designations for the Deutsch connector i am using at the engine side of the firewall.

[928drvr86.5]

The Deutsch connector itself with the color coding.

[Shane E]

Ben,

What does the customer need to get a harness made? Just the 25pin connectors from the old harness?

[Danglerb]

I plan on hitting a few "pick a part" places and getting the 25 pins off late 80's Volvo or Saab cars so a 928 harness doesn't need to die (even if its mostly dead.

quoted from Ben's post a few up ... items needed from old harness.

* The two 25 pin AMP connectors at the EZF & LH brains

* The green & white 1mm gage wires and two pin connector that feed the ignition triggers

* The oxygen sensor's green 1mm signal wire/plug and two pin connector

* The Central Electrical Panel, "W" connector.

* The idle adjustment, "TEST" connector from the front of the intake.

[Shane E]

OK no problem I have a spare harness. I can drop it in the mail today...

[Normy]

You're talking US model '85-86.5, correct?

N

[928drvr86.5]

Originally Posted by Shane E

OK no problem I have a spare harness. I can drop it in the mail today...

Shane, i am not ready to receive any donor harnesses yet. I still have an issue to work out on the prototype harness and at this time i am awaiting parts to do that. Once that first harness is complete i will order the bulk materials to build the harness for others, at that time i will accept the organ donors.

Originally Posted by Normy

You're talking US model '85-86.5, correct?

N

You bet, at this point i am working ONLY on the 85-86.5 USA models, perhaps other MY's to follow.

[928drvr86.5]

Last night i Completed fabrication of the harness and did a test fit of the section of harness on the engine side. Everything fit well except the #7 injector connector which i had to change from a "T" to a "Y" fitting at the breakout. There was some interference between the intake runner and the T fitting on #7.

I am almost ready to take pictures of the installation but first i would like to make a plywood layout board for the harness so measuring wires for additional harnesses will go quickly.

Someone mentioned installing fuses for the left and right injector banks, O2 sensor, and Idle Regulator, ETC., as you can see from the pictures i have indeed done that.

[928drvr86.5]

The connections inside the cabin

[928drvr86.5]

More connections inside the cabin

[928drvr86.5]

The 31 pin male Deutsch plug on the Engine side.

[Normy]

Whoops-!

Ben, you are to be complimented for your analylical abilities, and your electrical engineering talent. Guys like you advance this hobby, and make it easy to keep a fantastic series of old cars on the road. On the cheap. Kudos to you-

928 Motorsports out of Wisconsin already sells a complete new engine wire harness that they have built in their shop with better-than-Porsche wires. $589.

http://www.928motorsports.com/parts/wiringharness.php

N

[Danglerb]

Normy,

The harness Carl sells is just the 14 pin on the front of the motor to the alternator etc., you need it AND the harness from Ben to replace all the engine wires.