as the title states, I don't know what sources to wire the gauge up to.

The directions are ambiguous...

Red wire: 12V to battery
White wire: Illumination
Black wire: Ground
Orange wire: Ignition

The two that I am concerned with are the red wire and orange wire. I know what to do about grounding and the gauge illumination.

Do I really hook the red wire to a 12V constant source; i.e. always on no matter what? Or do I hook this to a "key in and click" source? Wouldn't hooking the gauge up to the battery as a constant source drain the battery?

and the Orange wire, do I hook this one to an ACC (two key click) source, or do I hook it to something that is only getting power when the ignition is turned on and the car is actually started?

I'm beginning to think that if this is the case with the wiring, the orange wire acts as a power feeder, only allowing the red one to get power when the ignition is on, and of course it would cut the power once the ignition is turned off.

Otherwise, I still need to figure out how the NPT fitting actually affixes to the temperature probe, because it doesnt look like it will unless welded to the probe. I know that a hole needs to be drilled out of the exhaust and the fitting welded to that, but the other side of the fitting that attaches to the probe itself doesn't seem to stick/stay unless I were to weld the probe to it. Sorry if that last part seems confusing, Im going to take it to a shop to have it installed anyways, so I'm sure they'll know what to do, but I just wanted to know on my own.

Oh ya, and I got a boost gauge too, just wanted to know what you guys generally think is better for reading. I know that there are two places that people generally tap into: the extra nipple on the UIM, and the MAP sensor with a 3 Tee fitting placed after the filter. Tapping from the MAP seems like it'd be more accurate, but I don't want to risk compromising the MAP sensors ability to actually get a precise reading. Doesn't the gauge take a teeny tiny bit of vacuum up to give a reading? If it steals air from the MAP sensor, doesn't this cause it to get an inaccurate reading? I know the amounts of air that the gauge uses are negligible, but I would rather tap off the UIM if that were the case...in addition to the fact that there would be an extra vacuum line in the map sensor, leaving a greater possibility of failure. Maybe I'm being waaayy too paranoid, but ya never know.

Any help with any of this appreciated.

 

The easy one. Just tap off the UIM for the boost.

The EGT is supposed to have a little retaining washer attached to the probe itself. The nut should be already attached to the wire above the probe. When you place the probe into the fitting after it's attached to whatever you're going to attach it to, the nut will press down on the washer and keep it in place. Make sense?

And yes. 12V constant and switched. You won't drain anything. The switched lead will actually turn the unit on. Just like wiring up an amp.

 

Ahh....thank you for clearing all that up.

orange wire: So, switched u mean, two clicks of the key, right before I turn the car on.

and the probe I have has that exact washer, but its not affixed to the probe. it came all in a separate bag. My probe looks IDENTICAL to the one that you have pictured, I just don't have anything hooked to it. No washer, no nothing. Hmm. and does the NPT fitting get welded in? or can I do this myself?

 

My old HKS unit looked like the one in Railgun's pics - the probe had a nut mounted on it that would tighten down to the other piece that screwed into exhaust manifold.



I just got my Defi EGT [d-gauge series] and noticed the exact same thing. The probe itself is "slick" without any extra nut.... What to do

 

ya, busy13b, u know what Im talking about. Im confused. Also confused on the wiring, but I think the orange one just wires up to a "key click" position if I am not mistaken. I can't imagine why I would wire it to something that is only getting power when the motor is running, although it doesn't make that much of a diff. does it? Anyhow, I am equally curious on both issues.

 

bump. anyone know what this is about? why did defi send their probes out like this? do I weld the washer to the probe? or is there some other way to fix it? and the wiring, I am REALLY starting to think that I need to wire the orange one to a source that is just key clicks, and obviously maintains power once the motor is started.

 

Yes, connect the orange wire up to an "ACC" source, so it sends power to the wire when you have your key to the "on" position...


I'll try to psot a few pics of the DEFI temp probe and the hardware that came with it, so people know what we are referring to....

 

That's the only way to get it. I thought there was a time when they were attached from the factory, but if you get one that isn't, you'd have to weld it. There's no other way I can see to get it to hold.

 

The constant 12v is mainly to maintain the gauge's memory of peak hold and what not when the car is off. I do know that the Greddy gauges wire up in a similar fashion and are grumpy if you don't wire them up right with the constant 12v.

Dale

 

Questions:
So, I gotta take the DP back off after all that work to get in on in the first place? grr. OK. Ill take it to a shop to have it taken off, and welded. Oh, and mount the probe to the opp. side of the turbos, about 1.5 inches off the flange? what sort of temps can I expect from this granted I am supposed to be running optimally or safely?

 

You MAYBE could install the probe with the downpipe still in the car - removing the rear intake pipe and Y-pipe might give you enough room to get in there with a drill. I've installed countless EGT probes - just drill, tap for 1/8" NPT, screw in fitting, rock and roll. Never had a leak, had one fall out, no problems whatsoever. I'd see if you can do it on the car - it's worth investigating.

From what I remember, about 780 deg. C is about the max you wanna see. You might see higher after sustained interstate cruising, but you wanna see about that at full throttle.

Dale

 

Im worried that if I drill a hole, metal shavings from the drilling might get into to the turbos being so close to the flange. And isn't there an issue with enough threads for an adequate tap due to the thickness of the DP?

 

The shavings will just fall straight down into the downpipe - they'd have to swim upstream to get even close to the turbos.

I've drilled/tapped MANY a downpipe, thin and thick, and have yet to have had a problem. Just use the right drill bit and tap, and tighten the bung down snugly, but don't over-torque it and rip the threads out.

Dale

 

No leaks either? I'm still skeptical, esp. with my abilities to drill a decent hole leaning over the engine bay and cramming a big drill bit onto a curved surface.

 

Okay, here is how the Defi D-series EGT probe is shipped [in pieces]:

 

And here is how it should look assembled:

 

So basically, if I am understanding the above replies Defi makes us weld the little cone-shaped piece on to the EGT probe itself, correct?

[positioned like this]:

 

Sorry for the large pics - here is a smaller one showing the alignment:

 

It looks like a compression fitting. If you tighten everything down (positioned like 3rd pic above), does it hold the EGT securely to the bung portion?

 

You want to have a 1/8 NPT bung welded into the downpipe. That way you can screw in the fitting they gave you, then put the probe in and tighten it down.

 

One would think. Mine sure didn't. As I mentioned, I ended up getting mine welded to the shaft.

Holy huge as pics. I can't even reply without scrolling over.

 

Err, sorry about the huge pics - i couldn't go back and edit my posts after I resized them




Did the welding get done to the top or the bottom of your cone-shaped piece?

 

you can see in my pics where. on the top side. works like a champ.