924Board.org

[bryanc]

My '82 924 na shows a drop in oil pressure when I turn on the headlights. I cleaned the grounding connection behind the fuse holder this weekend and cleaned up the aux. connections at the battery terminal but this did not help, but here is the real problem:
After disconnecting and reconnecting the battery during this procedure I found the car to run like c&*p. Does the computer need to "relearn" the car after being disconnected? It still runs OK but does not have the acceleration it had before.
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'84 944
I'd rather have a bottle in front a' me than a frontal lobotomy
Tom Waits

[Lizard]

the 82 924 only has the lambda computer which adjusts the air fuel mix slightly as per the signal from the O2 sensor, it doesn't need to be reset, if the car is running a slight bit worse, when was the last time the O2 sensor was replaced?

as per the oil pressure and other guages "dipping" abit when the lights are turned on, run individual grounds to each piece, and for the volt meter run a wire right to the battery for a more accurate reading. but also there is a gound point for each headlight it is a bolt that bolts into the chassis frame rails, clean this as well, also make sure no corrosion on female spade connectors for lights. also clean the plug for the headlight switch and if you are brave take the switch apart and clean all the surfaces good luck getting it back together though it is a PITA,

you would also be able to tap into the O2 sensor (or tap in another multi wire one) and run a air fuel ratio guage off of it, to see if you are running really rich or really lean
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3 928s,

[Ordrune]

The o2 sensor is probably cactus as Lizard said. An air leak in the inlet manifold could also send the engine RPM's up, i.e. o2 sender registers a lean mix and ups the fuel ratio - engine is now getting more air/fuel = higher RPM's. The Air/Fuel guage mentioned above is an excellent idea, but it has to be callibrated on a new sender after the car has been tuned (with the new o2 sensor) on an exhuast gas sampler.
Note....On a lot of EFI engines a hunt in the engine whilst idling is usually an air leak on the inlet manifold(9 out of 10 anyway).
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'79 924 supercharged,intercooled

[bryanc]

The O2 sensor was replaced last month, but I will take a look at the connections to it.
A bad ground at the headlights would cause the headlights to be dim but I don't know how that would cause the guages to read low.
I will try running a seprate ground to the center console and see if that corrects the oil pressure guage problem.
I don't have a problem with higher RPMs at idle.
I don't have EFI, it's CIS.
Maybe the battery is on its' last legs?
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'84 944
I'd rather have a bottle in front a' me than a frontal lobotomy
Tom Waits

[Ordrune]

My mistake sorry.

Try the engine earths, clean and wotnot. But it sounds like the lights are drawing its earth through the block which would do what you are saying. As you said run an earth to the guage direct to batt neg and if that fails try running the earth to the lights direct.

On the off chance its your regulator try reving the enginge with the headlights on and see if they get brighter/dimmer with the engine revs. If they dont the regulator is fine if they do the reg is cactus.

I hope it helps
Good Luck
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'79 924 supercharged,intercooled