Oil Pressure all over

[DFickel]

Installed oil press gauge other day, put it through real test today, worked great drivin from defiance oh to columbus, bout 1/2 hr before i got to cbus, oil press gauge started jumpin all over. It normally was at 40 psi, but would jump to 60+ down to fifty, stop then start jumpin again, never goes below 50, then it will fix itself at stay at 40 again. Now this is only at high speeds, once I slow down to 40 mph or less, the gauge works fine. Checked connections and wirin harnesses, everythin tip top, so any ideas?

[Schmieder]

Installed oil press gauge other day, put it through real test today, worked great drivin from defiance oh to columbus, bout 1/2 hr before i got to cbus, oil press gauge started jumpin all over. It normally was at 40 psi, but would jump to 60+ down to fifty, stop then start jumpin again, never goes below 50, then it will fix itself at stay at 40 again. Now this is only at high speeds, once I slow down to 40 mph or less, the gauge works fine. Checked connections and wirin harnesses, everythin tip top, so any ideas?

40-60PSI is really high for a warm engine. My car is about 40PSI cold then drops to 10-15PSI @750RPM when at ECT212*F. I would try disconnecting the ground wire to the sensor and see what changes if any. It seems like you have a broken wire somewhere as it is connected mostly but disconnects at the slightest bump. But that is only a guess at best. For the most part it seems like the issue is electrical and I would consider the effects of heat since you said it started acting up far into the trip.

If your set up is anything like mine I bet your Oil Press Sensor is about a inch left of the Starter. Make sure your OilPress Signal wires aren't resting on the Positive Batt Cable running to the Starter. Not sure if any EM would effect signal.

Another thing you might try, its a long shot but I had this problem once. Check the negative battery cable. What I did was use a jumper cable, secured it safe and connected to the Battery Terminal and then to a good ground. (DO NOT DO ANYTHING TO THE POSITIVE TERMINAL). If the negative wire is bad everything will be corrected. In such cases the intermittent disruption of the negative wire made my system act goofy then stopped when the cable warmed up (heat expands metal).

Question: Does your car stumble for 1-3 seconds during cold start?

[DFickel]

Ya, i recently did the classic head gasket change before she blew, so its only 6 months old, my pressure never really gets below 20-30, cold starts are fine, just give the computer a sec to check everythin and she fires right up. I thought it was a broken wire too, but it will be runnin fine, ill hit bumps on the road, and try wigglin the wirin harness and it works fine, then randomly 5 mins later it acts up. As for the long shot, this problem seems to occur when its hot, not cold. So you hooked a wire from the neg batt terminal to the oil sendor or to a better ground?

[pocket-rocket]

How is the oil level? If it only does it at high speeds (which would be high RPM), I wonder if the pan is being run dry when it starts bouncing around.

[DFickel]

thats the first thing i checked. oil level is perfect all the time. I disconnected a ground wire I had running from the oil sender unit to a ground and this problem has not happened again. I wonder if it grounded through the block and the extra wire was causin some interference perhaps.

[pocket-rocket]

I didn't figure it was oil level, but it never hurts to be sure. Glad you got it sorted out though. I know when the previous owner of the 92 changed the starter, he didn't tighten the positive cable down tight enough. The car would start fine and everything, but with the alternator being on the bottom of the LQ1, the + wire from the alternator goes under the engine to the starter + post. At high rpm my charging system light would come on and the engine would stumble a bit from lack of voltage. I changed the alternator thinking it couldn't keep up at high rpms but it didn't fix the problem. Then I moved on to redoing my positive and ground cables off of the battery and found the loose cable on the starter... I wasn't too much of a happy camper, so I know how you feel with the high rpm problem, but at least yours wasn't hurting performance.

[DFickel]

ha that woulda drove me crazy, ya at least the gauge wasnt droppin ill take high over low any day. But ya i've put prob another hundred miles on drivin around home and the pressure is reading fine so ill take it. I got my water temp hooked up to my trans so now I can monitor that, I'll have pictures up after bit here so stay tuned