alright i have a 88 iroc z with a tpi 355 in it that has maybe 8k miles on it. the whole time this motor has been in there, the oil pressure gauge has always fluctuated(sp?). what i mean by that is that itll just sit there and start moving up sporadically and then go back down to its original spot that it was previously at, or itll go kind of high and stay there til i let off the gas and give it gas again and then go back down to the original spot. this has worried the hell out of me and today when the needle was on the white mark that is 15psi im guessing, which ive heard is about where it needs to be at idle when its warmed up, it started getting a little under that mark and scared the **** out of me. ive always had engine problems and i really hope its the gauge or the switch or something. please help me!!!!!!all help is appreciated. thanks guys

 

The only way to be certain is to connect a reliable mechanical guage (temporarily, if you like) and compare oil pressure with the indication of the original "thing" on the dash. (I hesitate to use the term "guage".) You can often use the oil pressure port above the timing cover as a temporary test port, or simply install a 'T' fitting at the stock oil pressure transducer location.

RB83L69 had what is probably the most accurate description of the factory "instumentation". To paraphrase, they aren't guages or instruments by any accepted definition, but simply a trim package offered as a factory option. Don't bet your paycheck on them.

RB has a way of seeing through the smoke and mirrors and finding the truth in many areas, then relating them in easily comprehended terms. That is just another example of that skill.

 

Most likely it is the sender. I know in the earlier years the sender had a diaphram in it that the oil pressure pushed against which moved a potentiometer..the diaphram can/will get holes/tears in it that will cause the reading to fluctuate..a lot. If you replace the sender I would suggest an AC Delco unit, I tried 4 or 5 aftermarket senders (wells, GP and the like) and the "best" one lasted 6 months tops, the worst lasted less than a week. I finally broke down and spent the $30 for a Delco and it is still going strong 12 years later.

 

alright, i preciate the help guys. i was freaking out about this **** today lol. i work at a parts store so its all just a matter of actually getting it and putting it on in the parking lot. i also have a set of mechanical gauges that is a 3 unit set:coolant temp, oil, volts. the only one i have hooked up so far is the temp but i guess i need to get off my lazy *** and hook the other too up. now that i think about it, my damn factory voltmeter is always jumping around too, and so is the damn gas gauge......thanks for the info guys i really appreciate it.

 

All of your gauges are acting fruity? You may need to clean the electrical connections for the instrument cluster, they get tarnished as they get older.