Electrical Problem

[MitsubishiOwn]

I have a 1998 Mitsubishi Eclipse GSX Automatic with 83,000 miles that I just recently bought. I am experiencing an idle/running issue whenever I turn on my headlights. I have narrowed it down to the two aftermarket gauges that are hooked up one being a boost pressure gauge and the other being a AFR gauge. The previous owner had three wires running from the gauges into the engine bay along with one vac line for the boost gauge. One of the wires is wired into the high beam fuse in the under the hood fuse box. The other wire is wired into one of the electrical plugs coming from an o2 sensor. The third was just laying there in the engine bay not connected (so I removed it). The vac line runs up and there is a T fitting connecting two others lines to it.

My problem is that there is not a lot of room to remove the wire that is spliced into the wires right after the o2 sensor and I don't want to just pull on it and mess up the rest of the wiring from the o2 sensor because there is not a lot of room so I think I am going to take a few things off and carefully remove the wire.

Next problem: The vac line has a T fitting into two other lines and I am wondering if it would just be okay to put a fitting that just goes straight and connects the two and completely remove the line from the gauge?

[gofer]

I'm not sure what you're asking as far as the wiring issue goes, there really wasn't a question.

The boost gauge is necessary with a turbocharged car, why would you want to remove it?

[GTmitsu]

The wire that wasn't connected to anything is probably the ground. Do the gauges light up or even work?

The boost gauge will not work without that vacuum hose. It is probably T'd in to the FPR hose. That is a good spot for it, so don't move it.

[MitsubishiOwn]

Originally Posted by GTmitsu

The wire that wasn't connected to anything is probably the ground. Do the gauges light up or even work?

The boost gauge will not work without that vacuum hose. It is probably T'd in to the FPR hose. That is a good spot for it, so don't move it.

Sorry I know there wasn't really a question (after re-reading it). Why is the boost gauge necessary with a turbocharger when it is completely stock and is not being messed with? And I need to at least temporarily remove it do to the electrical issues it is causing me.

The boost gauge works when headlights are off and when they are on it doesn't work. The boost gauge does not light up ever but it works! And yup it is T'd to the FPR hose but I think I am going to remove it and plug it or whatever.

[GTmitsu]

It's there to monitor your boost - the pressure in your manifold. Without it, you won't know how little or how much boost you're making. In the case of too much boost, shit can hit the fan. It's not always necessary in stock applications but its not hurting anything if u have it. I think you should rewire all the electrical stuff. Completely remove it, then reinstall it the right way. You could have a short somewhere and not know it. Like where the wires run through the firewall could have rubbed to make contact with metal.

[gofer]

Originally Posted by MitsubishiOwn

The boost gauge works when headlights are off and when they are on it doesn't work. The boost gauge does not light up ever but it works! And yup it is T'd to the FPR hose but I think I am going to remove it and plug it or whatever.

You're saying the boost gauge never lights up, assuming its mechanical then? So, if it's an aftermarket boost gauge and it's mechanical it moves off of vacuum/pressure and NOT an electrical signal. There is NO WAY that the boost gauge operates with the headlights off and then, once you turn the headlights on, it no longer works. Because, if that were the case, then your motor would be shutting off when the headlights come on too.

Now, the stock boost gauge that's up in the gauge cluster that doesn't actually use a pressure source to get its reading is electrical and not really a boost gauge. It functions using a signal from the ECU which is derived from the MAF and RPM signals.