I have 3 gauges from Megan Racing. Oil press., air / fuel (narrowband) and water temp. I got them used and there are no instructions. All 3 gauges have a Red, Black, and Purple wire and one unique color wire per gauge. I know the red and black wires must be power and ground. My question is: Is it safe to assume that the different color wire in each gauge goes to the sensor in the engine bay, and the purple wire goes to the dimmer/ headlight ?
It only makes sense to me that this would be the case, seeing as there is only one unique color per gauge, but just looking for some reassurance.
Thank you.
so i went ahead and did it this way, but it didn't work. All the gauges are on all the time, even with the key out, and they don't have any readings. wtf....
I only hooked up the water temp and a/f ratio. I spliced the yellow wire on the ECT harness and the purple wire on the Primary O2 Sensor. I then used an 'add a circuit' and hooked them up through the 25amp wiper fuse ( I read someone did this instead of splicing the wire for the headlight / dimmer). Even when I unplug the add-a-circuit all the gauges stay on.
Could they be malfunctioning because I didn't hook up the oil press gauge? All three ground, power and remote wires are spliced together. As it sits right now the wire leading to the oil pressure sending unit is the only one not connected. F.Y.I. power is straight to the battery, and ground is on the ground strap towards the back of the cam cover.
Any help would be greatly appreciated. I'm soo frustrated....took the whole day and got sweet @!#$ all, but a light show that won't quit (even though i kno thats all i'm getting from the narrowband).
So I think i just found out i'm retarded for going straight to the battery. Thats why they are always on. found a wiring diagram . "Red : +12v ignition switch". So the wire will be under the steering wheel?
"Purple: Dimmer/+12v to dim connect to headlights to activate" - That should still be ok connected to the wiper fuse. Do i have to put a fuse for the gauges as well?
You don't have to use fuses for you gauges power wires. That's your decision if you want them but not necessary.
I also wouldn't worry about dimming the gauges because most of the time, they'll need to be bright enough to be able to see in the daylight and at night too.
All the gauges in my ride are a direct hookup to ignition power with no dimming and I'm quite happy with this arrangement and I also like keeping things simple for installation purposes.
I'd also reroute your grounds to under the dash where there's metal there that is perfect for your grounds.
I'm sure you'll find a screw under there that will suffice for this.
Make sure that your splices are sealed if they're under hood.
It's best to solder your connections and either tape or even better use some kind of 'liquid tape' or ScotchKote to seal the connections from the underhood environment.
I usually solder splices like yours then scotchkote the connection with several layers to seal them and then tape them to complete the connection.
Sure it's alot of work but you'll have a connection that will never fail and probably last longer than the car itself.
Good luck and holler if you're needing more help.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO! 
You the man Blu, thanks for the help.
Now: I re-routed the ignition power from the gauge to my deck, so they turn off now like they should. BUT still no readings on the gauge. I started with the ECT and checked all the voltages. I checked stock yellow wire from the ECT sensor . The wire from the gauge to the yellow wire and they both read the same. So I AM indeed getting voltage to the gauge. But still no readings. Does this mean the gauge is bad? Is there any other tests I can run to verify if the gauge is working properly?
Temperature reading is usually done with some kind of thermister or in some situations a K-type temp sensor that has to attach to something in the water system.
I've seen some of these sensors that couple a hose together for the reading of the temperature and other through a sending unit.
If you don't have the sending units for the oil pressure gauge or the temp sensor, that's probably why you're not getting an actual reading.
Make sure that you've got all of the hardware for the install and not just a bunch of gauges.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
Well Blu, like always you were right. I do in fact need a sending unit for the water temp. gauge. I called Megan racing and spoke to a very helpful tech. and he explained the whole thing to me. No wonder the gauges were so cheap!
The tech. also told me that some cars come with O2 sensors that give out readings from 0 - 5V, in which case the narrowband gauge I have will not work... another disappointment. Guess i should have researched more before I tried to install.
Lesson Learned.
Your narrow band gauge will work as you don't have a wideband setup for your car.
No Jbody has a wide band or 0-5 volt readout so you're good to go on your a/f gauge.
Sounds like you're on your way with the installation once you get your sending units in from the manufacturer.
Good luck with it.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
Got the A/F Ratio up and running tonight - Finally some progress! Looks great!
http://h.imagehost.org/view/0166/DSCI0008">DSCI0008.jpg
still getting use to posting pics. I'll try to get bigger ones for ya'll
Looking good and much better looking than my old school gauges.
Nice work man.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
Can't wait to get them all hooked up now. Just waiting for the fittings to arrive for the oil pressure. Still have to find a suitable water temp sending unit. 0 - 300 Degrees F full sweep electrical is what I need. Hooking it up to the megan racing hose coupler 'thing':
http://meganracing.com/product.asp?prodid=791&catid=82
I have to insert the adapter on a section of hose, then thread the sending unit (sensor) into the adapter. The best place would be where the fluid is the hottest right? Suggestions? Can I just feel all the hoses and see which one is hottest and tap that one?
That depends on the size of the adapter you're getting which will determine where to mount it.
Once you get it you'll know.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
True. I have a choice of 3 sizes: 1 3/8", 1 3/16", and 1".
Very nice setup man and looks really good.
Now you can monitor all the vitals like you're supposed to which is a good thing.
So you must've used an L-bracket to mount the gauge to the top of the steering column, looks good.
Enjoy the setup.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
Update with the Megan Racing gauges: Problem with oil pressure gauge!
My oil pressure gauge reads max psi (over 100) any time the engine is not at operating temperature. It never used to do this. It use to be at 70-75psi on cold idle and settle down to the regular 25-30 psi when the motor warmed up.
I can see the gauge twitching on its way down to 30 psi when i'm on the highway, after about 20 mins. No obvious leaks detected, and signal wire is still properly connected to sending unit.
Any ideas?
Hmmm, that sounds normal for my setup.
But I am running a Behr oil cooler along with a larger filter setup than stock too so that may have something to do with the higher pressure when it's cold.
Once it's warm though it's in the 30 to 35 range with about 55 psi on the throttle.
Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!
