electric gauges...and electricity

[kdillard21]

Just wondering if it is normal for my electric oil pressure and temp gauges to fluctuate depending on whether my lights or a/c heater is on. If I turn any of those on, the oil pressure reading drops like 10 psi and the temp goes up 15 degrees. However the water temp gauge is not affected and they are all to the same ground. Anyone else see stuff like that?

[the head]

no that is not normal check for loose ground and power wires what is the power tapped off of?

[kdillard21]

I took the power from the battery, then wired in a relay with the ignition so it wasn't hot all the time. however, I did wire all three ground wires from the gauges together and ran one wire to a common ground to a screw I put in the fender well in the engine compartment. Seems like it is working for the other gauge (water temp) though.
thanks

[fliprayzin240sx]

well, wut gauges are you running. If you say autometer then imma just sit here and laugh at you. Theres your problem rite there. For some reason autometer guages do stupid shiet like that.

[kdillard21]

Megan Racing's new gauges, no one else reported this problem...although I know they aren't top of the line.

[SirWarrior]

It definetly a ground issue, my guess is that its somewhere on the block.
but thats only assuming that your water temp gauge isn't installed into the block but into the radiator hose.

[kdillard21]

right, the water temp gauge probe is in the upper radiator hose, how else would i ground the oil pressure/temp gauges, since they are through the block, i can't run a wire I don't think....well maybe i can, i used a greddy oil filter adapter on for the two gauges.

[the head]

well, wut gauges are you running. If you say autometer then imma just sit here and laugh at you. Theres your problem rite there. For some reason autometer guages do stupid shiet like that.

funny i have used autometer in three cars now and have had no problems at all, gee i guess that is why most US racers use autometer cuz they suck right?

[90RS13]

yeah, I don't know why some people on here say they suck. Maybe they had bad experiances or whatever. I've used gauges from them and they worked perfect, and almost all the hot-rod/muscle-car guys I know use them with no problems.

[kdillard21]

yeah i think autometer is fine, i just didn't go with them. however, tell me how you guys who aren't having any problems have yours wired up, specifically grounding.
thanks

[90RS13]

I don't have anything in the s13 right now, but in my wife's avenger, (6g73 v6 w/ a604 atx) she had a electric tranny temp (a604 is bad about overheating), grounded to the block. It never had problems.

[SirWarrior]

I would check the ground strap on the block and add one somewhere near the sensors just in case.
It can't hurt and ground straps are cheap.

[the head]

yeah i think autometer is fine, i just didn't go with them. however, tell me how you guys who aren't having any problems have yours wired up, specifically grounding.
thanks

all of my gauges are grounded to the cross brace in the dash

[kdillard21]

how would you ground the gauges to the crossbar under the dash? You mean the power ground? because the actual sensor is ground through itself to the block...I am using a Greddy Oil Filter Adapter to mount the sensors, so maybe its not getting good ground. I will try running a wire off it to the frame of the car.
Kyle

[the head]

i was talking gauge ground (power ground)

i replaced my oil pressure switch with the new sender
fuel pressure was threaded into my jgy fuel rail
water temp is tapped off of the head temp unit for my standalone
all were just grounded by their casing

but if you are having sensor fluctuations i would lean towards a power ground problem than a sensor ground check all of your wiring fro the gauges and also as said above check your ground straps from chassis to motor

[kdillard21]

Ok I put my voltmeter on the engine block, without the engine running and got 0.0 ohms resistance from the block to the frame, then i cranked it up, and got got about 14 ohms resistance from the frame to the block. Wierd, then I turned on the headlights, and the resistance went to 34 ohms, so this thing has got some major resistance through the block, but only when its running. What is up with that? Still think its ground straps.

[rps13_fastback]

And I thought I was the only one with this problem. I just bought some POS Megan Racing Boost and Oil Pressure gauges... my friend got them at the same time too. I have the same problem as you, when I turn on the headlights, it would drop about 10PSI for the oil pressure (not the boost)... and when you hit the brakes it drops another 5-10PSI. I'm gonna try to wire it again from a different source..

Oh yea my friend has the same problem but it's not that drastic.. it only drops about 2-5PSIs when you hit the headlights or brakes.. go figure

[kdillard21]

that is crap, so now we are getting somewhere.
But my water temp gauge doesn't do it at all. Keep me in the know on what you do to fix it. Silly Megan Racing.