I have replaced my oil pressure sender twice now and the needle continues to freak out when idling in gear. The needle slams back and forth until I either start driving again, or if I put it in Neutral. I thought that was odd.

There's no leaks, and the oil level is correct. I'm running a 0w40 synthetic, if that matters.

Any suggestions on where to look?

 

Maybe you have a short or an intermittent break in the loom wire. Take a look from the sender onwards.

 

 

Maybe the engine shifts a bit when you do that?

 

Putting it in neutral will be the same as accelerating it a little, as the RPMs rise, right? Could be wiring but the behavior sounds like its the gauge, perhaps the resistance is right on the cusp of not moving the gauge so the little variance you get in pressure is causing it to constantly go back and forth over this threshold until higher RPMs consistently get it past the threshold?

 

If you're having issues with your fuel gauge and oil pressure gauge I would be highly suspect of the gauge cluster. Maybe pull it out, clean the contacts, and add that auxiliary ground? That would at least rule it out..

 

See what happens to the guage with sender unplugged and also with that connection grounded?

 

Could always take a reading off that pin with the gauges unplugged. If you are getting reading all over the map, check the wiring to the gauge or gauge itself. If you have consistent reading, now you know for sure the cluster is the problem.

 

Yeah, you're right. Unfortunately, it doesn't always happen. It seems to occur once the car has really been driven for awhile in the city.

I'll keep my multimeter in the car with some alligator clips...

I'll report back eventually.