Help with gauges

[jschweig]

I have a 86 944t and need some help with some gauge problems.
I recently rebuilt the motor and all sensors and senders are new. I also examined the wire harness and did not see any problems. First the oil pressure gauge moves to show oil pressure at the 4 or 5 mark at speed or at idle. However, sometimes after the engine is warmed up the gauge will drop down to 2 or 3 at idle and then bounce rapidly there. I am getting the same type of response from my temp gauge. It shows what the temp should be, a little above the first mark, but then sometimes bounces rapidly. Any sugestions?

Thanks,
Jonathan

[1.2gees]

The bouncing is usually related to bad (corroded) grounds. There are several of them under the dash as well as around the bellhousing inspection hole (speed and reference sensors) that are worth looking at. Also near the HVAC system (under the black plastic cover at the base of the windshield). In addition the bouncing oil pressure gauge can be caused by the oil pressure sender wire shorting out on the block near the waterpump and/or an oil pressure sender that's on it's way out.
Ahmet

[jschweig]

I know where the grounds are under the hood, one on the bell housing and one next to the battery under the lip of the black plastic below the windshield. Correct? And the oil pres. sender is new. Any help at where the grounds are under the dash?

Thanks,
Jonathan

[1.2gees]

There's another ground under that black cover (you need to pull it off to access these) near the blower fan, however that should have nearly no effect on the gauges. The grounds under the dash are near the steering column. Look under there and you'll see them (above the clutch pedal, near the cruize control brain). A search in the archives would explain some stuff for you, this has been covered in length.
Ahmet