951Porschiste

Ever since I got my 951 back in 2003, it's been plagued by a no-start problem when the engine compartment temperature got a little high and when the humidity was at a certain level. I eventually learned that by wiggling the speed and reference connectors behind the intake manifold, I could "cure" the problem.

Now, our cars are getting up in years (20 in my case) and the wires running through the engine harness are showing their age. I don't have the time to rewire the whole harness but I figured I could at least redo the wiring from the connector plugs all the way to the DME.

I got some shielded (braided) two-pole wire from my local electronics store. Then I got some new three-pole AMP female connectors from EagleDay.com are well are some extra pin connectors, colored heat-shrink material, and some heat-resistant shielding loom.



I assembled my new "speed and reference harness" this afternoon and plugged everything in. The car fired up on the first attempt! Then I went from a drive to make sure that the engine compartment and the humidity would rise to the level that usually provoked the no-start situation. I came back home, let the car sit for about 10-15 minutes. When I cranked it after that short delay, it fired right up!. With the old wiring this delay and heat and humidity would have caused a no-start for sure.
I've restarted the car a couple of times since and it always starts right up. I'm now pretty confident that I've solved this nagging no-start problem!

Trucho-951

951Porschiste, Congratulations on an excellent fix! I've been looking for 3 pole AMP male connectors to fix my broken sensor connectors, but alas, have come up emptyhanded. Any suggestions?

hosrom_951

So you basically replaced the reference sensor harness from DME to connector right?

How much did you get the shielded (braided) two-pole wire for? best price i found was $1 per foot.

951Porschiste

Yes, that is correct. The tricky part is at the DME connector plug. The shielding wire of the reference sensor shares a connector pin at position "5" with another wire. I decided to merge this other wire with the shielding wire into the connector pin. I did the same for the shirlding wire from the speed sensor at position "23".

Would you believe 0.55 cents CDN per foot?

potent951turbo

Great job, I know I have had the same problem as you on my old 951. Any chance you want to start making them for the rest of us?

951Porschiste

That's a good idea. The biggest problem would be getting the AMP female connectors. A "connector kit" comprises the plastic connector itself, three connector pins, and a rubber boot. One " connector kit" is about $25 US. Two are needed, so do the math. Plus, about a foot of heat-resistant sleeving, plus the shielded wires, plus some colored heat shrink material. Still, it can be done!

Let me think about it

951Porschiste

Here's a picture of the speed and reference harness in place. Notice that I have removed the connectors from the holding bracket at the back of the intake manifold to make the picture clearer. The new harness is on the left and the wires from the sensors themselves are on the right of the picture. The wires are wrapped in heat-resistant sleaving. The wires are color-coded to make identification easier. Red goes to the reference sensor, yellow goes to the speed sensor.

Ski

Looks great! What pin removal tool or what did you use to get the pins out of the DME connector?

951Porschiste

I designed my own pin removal tool by filing down a small allen wrench. Here is the text from a previous thread a few months ago (https://rennlist.com/forums/944-turbo-and-turbo-s-forum/277617-need-help-with-dme-klr-plug-connector-update-problem-solved-pics.html):

To remove the metal pins from the plastic connector, you need a special tool that will disengage the "locking tab" (see arrow in next picture):



I went to the local electronic store (ex-Radio-Shack, they are now called "The Source by Circuit City" in Canada) and could not find an adequate tool. So I decided to fabricate my own using a 1.5 mm allen wrench which I tapered down (see next picture) using a Dremel rotary tool.



Once I had the modified allen wrench, I then inserted this tool down the little plastic valley of the connector as seen in the next picture. This disengaged the "locking tab" and then I just had to pull on the wire to take it out.



And Voilà! Problem Solved!

Ski

Nice work and macro photos. Thanks.

hally

great info thanks

951Tom

So far I can only find 18AWG, 2 conductor, shielded wire with a temperature rating of 75C or 167F. Do you guys think this is ok for under a 951's hood? I've seen automotive wire that's rated for higher temps like 125Celcius, but it's not shielded or 2-pole. Andre, did your wire have a temp rating written on it? Thanks!!

Tom
'87 951

951Porschiste

It's rated at 105 degrees Centigrade which is a little over water's boiling temperature. Don't forget that I wrapped these wires in additionnal heat-resistant cable sleeving from EagleDay.com

theedge

http://aircraftspruce.com/catalog/el...shieldwire.php

That is what I used, at the bottom there. 2 conductor 22 gauge Milspec shielded. Good to 150 degrees C.

adrial

Andre and others that have done this,

I am able to remove a few pins with some effort, but I can't get most of the others out.

Mine have a locking feature on either side of the pin, whereas it sounds like the one you are describing only has a locking feature on one side? Looking at my pictures...does my setup match yours? If so, any suggestions?



There is one of these plastic retainers on each side of the connector:


Which leaves a DME connector that looks like:


TIA,
Adrial