badass951

I am beginning to think that my temp gauge problems may have to do with bad grounds. I have also noticed that my volt gauge is only reading around 12, when I swear it used to read something like 14. My oil pressure gauge is moving/flickering as if it were an electrical problem between 2-3, but at higher pressures it reads fine. Next, my a/f gauge appears to flicker a lot, especially under boost.

My temp gauge appears to increase in temperature when I open or close a window, and when I check the temp on the gauge when the engine is off, it appears to be getting hotter until a certain point.

What grounds should I check first?

led

I would put a voltmeter on the battery first, while the car is running, to check if the alternator is working properly.

On my car the temp rises when I turn it off but I think it's normal because water is no longer flowing through the block.

badass951

I just thought about this and figured it may or may not be related. The light under my hood can be seen flickering under full throttle at night (I am sure it always happens, just visible at night), so I was thinking this may be a ground issue as well. Although this has been going on since I bought the car, when all the gauges read fine - also since I have a GT Racing vented nose panel it could just be causing the hood to lift a little, since it is only under boost.


On a side note - I have only had the car since the middle of March, and I swear I have not had a problem free day yet. I have easily spent $3,000 (basically every dollar I make) on maintence since the time of purchase. Luckily I love the car too much to think negatively, however it has only been one day after it came from back the mechanics, and more problems already...rediculous.

Randy_J

Sounds like bad grounds - the common panel ground is under the dash on the drivers side, way up above the hatch release. Check that first. It's easy. Just lie on your back on the drivers side floor, use a flashlight to shine up there and look for a bunch of brown wires all ganged together with a 10mm bolt. Tighten it up should suffice, as not too much can corrode that terminal.

The tougher one, and probably the real cause is the main block ground on the bellhousing. That's just below the heater control valve at the rear of the engine just in front of the firewall.

The real hazard in checking that is you have to be REALLY CAREFUL not to drop any tools (like a 10mm socket that fits that ground strap nut!) or the nut itself into the Clutch Inspection Hole that is immediately below all that stuff! USE DUCT TAPE to seal that hole, or face a LONG process to get whatever you drop down there (Murphy's Law was written just for this) out of the clutch bellhousing. Read other threads about that.

The bellhousing ground strap is prone to corrosion, etc. so it's a good time to clean it up and use some good dielectric grease to keep everything nice and happy down there....

Hans

There are possibly 2 or 3 under the dash, all M6 (10 mm hex head).
There is one more: Main body ground, in the tray / fire wall, behine the battery, M8 x 20 (13 mm hex).
The ground for the front lights is in the frame rail on the outside. One on both sides, the left one under the pop-up motor assy.
There is one in the trunck on the left side under the lamp fitting behind the carpet for the rear lights.
There must be at least one more under the foot rest in the passenger side well for the motor management system.
Advised is to replace the bolts with stainless M6 x 12 mm ones.
Clean lugs with 3M Scotts bright and apply electric grease.
You might want to consider an additional ground wire to the engine.
TakeCare

97xray

Early cars also have a ground on the front of the cross member under the engine - while it's only a little guy, mine was corroded awefully and worth a cleaning.
I don't know if the late models have this or not.

badass951

Just cleaned off the ground connecting to the battery, and I already seem to have a lower temperature on my temp gauge, and it did not rise or fall as drastically. Also, it brought the battery volt gauge up slightly above 12, which is better, but I don't think quite as high as it was.

There is still some fluctuation when I go over bumps, so I know my problems are not solved yet, but I already feel a little more confident. I am guessing the ground by the bellhousing is my main issue, because the mechanic did install a new heater valve, and probably touched that ground in some way.

Any other grounds I should check?

pete944

If you mess with the bellhousing ground point, don't forget to cover the clutch inspection hole under the heater valve.
I know Randy_J already mentioned this, but it's worth repeating.

Roy LaZelle

You can do a quick test of your ground condition by:
(1) running one jumper cable from the battery ground post to the engine
(2) running a second jumper cable from the battery post through the window, with a small alligator clamp to attach to the ground point above the hood release.
--Roy--

Big E

FYI, that's normal, called "heat soaking." No coolant or air moving around, thus things get hotter. It's amazing how much faster the engine will cool once off just by opening the hood (that whole heat rises thing).

Mike S

You might want to try adding another ground. It's cheap and easy. If that solves your problem you can then go about cleaning up the remaining ground wires if needed. I added one from the bell housing to the passenger side rear caster bushing bolt. That made a world of difference and solved my woes.