Current flow wiring diagram

[tracer]

I am installing the FI the PO removed from my 1.8 L-Jet, I have most of the harness connections completed. I have 3 white wires in the cable in the protective covering together which have no end on them, just taped together. Is there an easy way to tell what they are for? The wires have the numbers 40 and 12 and one does not have a marking on it. They come out of the loom about a foot before the ECU connector shoe.

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Thanks,

Brian
'74 1.8L in resto

[bowlsby]

Those 3 wires do not go to anything. They just remain unconnected. Trust me. They merely tap into the ECU connector for some unknown reason...speculation that maybe there was a european-only accessory or some such thing. Leave them loose, they do nothing.

[jabez]

I believe these three wires were for cars sold in high altitude areas and had some sort of compensator connected to them.

[Clay Perrine]

The wires are for the altitude compensator. I have never actually seen one, but I would love to get one. I want to take it apart. I figure that I could decipher the circuit, I could build a box to use an O2 sensor to adjust the mixture and keep the car running better and more efficent.


Clay Perrine

[bowlsby]

Thats interesting to know. I searched for months for the answer to those three wires and came up empty handed...have not heard about an altitude compensator before on the L-Jet cars. Don't remember it in any of the manuals or other literature.

Every L-Jet car I've seen just has the 3 mystery wires not connected to anything and without wire terminals.

Where (what countries, markets, etc) were the altitude compensators provided for?

Was it an owner ordered factory option, or did the factory just decide when/when not to install them?

What else do you know about them?

The D-Jet system has an integrated altitude compensator in its pressure sensor design, and therefore doesn't need any other compensator, of course the L-Jet works on a different principle.

Hey I wonder if Bosch made one for other L-Jet cars that could be obtained easily enough that would work? Maybe VW, BMW, MB etc.

[Dave at Pelican Parts]

Jeff, check Fig. 2.37 in Haynes, "Optional barometric compensator". No other info than that which I can think of, though.

--DD

[bowlsby]

Thanks for the reference Dave, will check into it.

Another tidbit: The 74 1.8L cars seem to be the only cars with the FI harness having the 3 wires for the 'barometric compensator' (BC). The 75 cars have an identical FI harness, but without the 3 wires. I've only seen a few samples of each, so there may be exceptions, but that seems to be the trend anyway.

Since the BC seems rare (and its probably not necessary unless at high altitudes (Denver?) anyway, I only need to make the harness without the BC wires. Thats great, one less harness type to be concerned about.