[RESOLVED] EGT acting wacky after battery relocation

[j_eclipse96]

Alright, so after ordering a new screen for my logger, my EGT decides to take a dump on me, conveniently after I finish installing my MAFT G2.

It seemed to start acting up immediately after I relocated my battery to the trunk. After 15-20 min of driving, the EGT will stop acting normal and drop to zero, then hang around 0-400 degrees, spiking every once in awhile. It seems to relate to the car's electric system, because when I turn the lights on/off or turn on the radio, the needle goes up or down in sync with the switch.

The gauge is an Autometer Sport Comp II EGT gauge, with an Autometer probe. Is this most likely a bad probe, which coincidentally went sour during the battery move? Or could it be electrical related? Thanks.

 

[97EclipseGSX]

Alright, so after ordering a new screen for my logger, my EGT decides to take a dump on me, conveniently after I finish installing my MAFT G2.

It seemed to start acting up immediately after I relocated my battery to the trunk. After 15-20 min of driving, the EGT will stop acting normal and drop to zero, then hang around 0-400 degrees, spiking every once in awhile. It seems to relate to the car's electric system, because when I turn the lights on/off or turn on the radio, the needle goes up or down in sync with the switch.

The gauge is an Autometer Sport Comp II EGT gauge, with an Autometer probe. Is this most likely a bad probe, which coincidentally went sour during the battery move? Or could it be electrical related? Thanks.

How did you do your ground and charge wire to the battery and the 12v supply to the fuse block?

Sounds like a ground issue.

Where is the egt grounded?

 

[j_eclipse96]

Ah.. I just took a gander at the writeup for relocating your battery. I wasn't aware you had to run a cable back to the battery for the ground as well as the power, so I just grounded the battery in the trunk, and bolted down the grounds in the engine bay. I'm guessing this is why my EGT gauge is acting strangely?

 

[97EclipseGSX]

Ah.. I just took a gander at the writeup for relocating your battery. I wasn't aware you had to run a cable back to the battery for the ground as well as the power, so I just grounded the battery in the trunk, and bolted down the grounds in the engine bay. I'm guessing this is why my EGT gauge is acting strangely?

It's possible but not guaranteed. Only reason I would reccommend checking all of these things first is because you said it worked before doing the relocation. You didn't by chance jump positive to ground on accident when taking the cables off or on did you? It's possible you could have fried it if so.

If it acts up when the car is sitting, run a jumper cable from the battery to the motor (clear of moving parts of coarse) and see if it helps. Turn everything on so that power usage is as much as possible. (AC or heater, radio, engine fans, lights,...)

You do have at least an 8 gauge ground wire going from the body to the motor/transbellhousing still right?
What size battery to chasis ground did you use?
Another idea is did you make sure the bolt and surface for the ground was nice and clean/paint free?

I didn't run a ground wire from the battery to the front. It shouldn't be necessary if everything else is correct.

 

[j_eclipse96]

1. Don't think so.. My battery was dead during the entire relocation, due to a power drain that I have yet to find.

2. Alright, I'll try that when I get a chance.

3. I have the factory grounds bolted to two different places, both of which are clean and sanded down well. I used 2 ga. wiring to ground the battery in the trunk, and sanded down the paint before bolting it up.

4. That makes me feel alot less foolish

 

[andy4g63]

I had a similar experience with my Greddy EGT. I just swapped manifolds; from evo3 to a FP, put the new mani and nothing. Only steady red light from the gauge, no readings.
When you think, what did I do?
Nothing,just unscrew the probe, put new mani in, put probe back on . The probe decice to take crap on on me at this very moment. So just check the battery again and hope is just that, not the probe.

 

[j_eclipse96]

Fixed. It was the ground. I didn't have the two factory grounds connected to eachother.

Thread can die now!