Oil pressure really low and high after changing sending unit

So I bought a used Tundra about a month ago, and the oil pressure would go very low when I was idling at a stop light. Looked it up and found out that the set oil pressure at idle is 4-5 psi. I still thought it the gauge was reading pretty low, so I replaced the oil pressure sending unit. After I did that, my oil pressure gauge shot all the way up and wouldn’t go back down. So I went back to oreilys and returned that sending unit for another one. This time after the install, my gauge was reading negative pressure and won’t rise when giving it throttle. I also replaced the oil filter so I know that’s not clogged. Anyone have any ideas of what the F*** is going on here?

 

sounds like its faulty sending units honestly. if you still have the original i'd reinstall it and see if it works again

 

Try a aftermarket mechanical pressure gauge that doesn't have a sending unit. My old truck would run 100psi then drop to zero then spike to 100psi it whose the sending unit kind of nerve-racking going down the interstate with zero psi LOL.

like

$70 AUTO METER 2325 Autogage White Console Oil/Volt/Water Gauge with Chrome Steel , 2.3125 in.

https://www.amazon.com/Auto-Meter-2...d=1&keywords=AUTO+METER&qid=1592132030&sr=8-1

 

This is exactly what I would do.

For anyone reading this and is new to our trucks, then realize low oil pressure reading in NORMAL at idle. This freaks people out. Its NORMAL.

A couple of observations:

1) Never heard of our 4.7 engines dying from oil pressure issues.

2) Our 32 OHV engines are built to run with the low idle oil pressure.

3) Oil pressure sending units (aftermarket) seem to not work on our trucks.

4) Never heard of anyones Oil Sending Unit ever failing. Not saying it can’t happen.

 

okay, but my stock gauge worked fine until I put the replacement sending unit. I’m gonna put the original sender back in and see if that changes anything.

 

1. Have you ever heard of replacement oil sending units causing a dash gauge to do that?

2. I don’t know if my original was failing. I only replaced because it would read like zero or 1 psi (I’m guessing those numbers) when I was stopped. Like the needle would lay flat with the low line on the gauge, but then go back to normal levels once oh gave it gas

 

Post up a pic of your idle pressure reading on the guage.

 

Take a picture of it with the original sending unit or the new one? And quick question.. do the 03’s come with a low oil pressure light? Mine doesn’t come on when I turn the key

 

here a couple pics. 1st one shows my gauges before I start it up. Notice there’s no low oil pressure light. And the second is it running after I started it. Both the aftermarket and original sender displayed the same readings on the gauge. I’m lost now. This was done on a cold start because I don’t want it running too long.

 

I’m not in a place to check my truck at cold start up at 1100 rpm.

I believe my gauge reads where yours is reading at warmed idle in DRIVE in a stopped position with the RPM at 525-50 range.

Why is your check engine light on?

 

Usually with a cold start on this truck, the oil pressure will read at the halfway point and once it’s warmed up it’ll idle at about quarter way and lower.

the check engine light is because both my cats are bad. It’s was on before I changed the sending unit

 

And do you have a low oil pressure light on your truck? I don’t know if mines burnt out or it just doesn’t have one

 

Sounds like normal oil pressure readings to me.

How many miles on the truck? Your o2 Sensors (4 total) might be bad and maybe not your Cats. Our o2 Sensors tend to fail early (especially the forward 2) in front of the Cats. Densos cost about $45 each. The rears are easy swaps. The fronts require Gorilla Arm Technique.

 

I have never seen mine come on or even know if there is one. Sounds like you have normal pressure based on my experience of driving my truck for 18 years. I believe your gauge is the only monitor.

 

yeah I don’t think the SR5’s have one. When I went to buy the new sending unit, they asked if I had the dummy light or an actual gauge. But I was just wondering

 

No my oil pressure gauge used to rise to the halfway point and above when I accelerated. Now it’s stuck at the quarter mark when I cold start it. And drops when it warms up. Just gonna bring it in. I don’t like driving around with funky oil pressure readings. Too risky.

My truck has about 185,000 miles on it. But I check the CEL with a code reader and it only said my cats were bad. I already replaced the bad o2 sensor a couple weeks ago.

 

Snapped a pic yesterday and posted it on another members thread about oil pressure. My truck is in ‘D’ with foot on brake and the E-Brake engaged in a parked position.

 

LOVE the blue tint on the illumination ! Thanks for posting ~ my oil pressure gauge hovers just above the L as well . . .

 

Thanks. Wanted something different. Gives good contrast during daylight hours. I prefer just the white bulbs for straight night driving. I pulled the OEM green rubbers off and drove that way with the whites for a little while before the Blue Switch Over. The whites show off alot of the Red/Orange on the panel. The Blue cancels those out.

 

when i bought my second toyota truck ,a '90, first was an '85, I noticed this on the drive home from the dealer. the oil pressure was falling to what i thought was dangerously low. I turned around and drove back to the dealership. I was told that this was normal operating range for idle. something new i guess since i never noticed this on my '85. Just got my '04 tundra and it does the same. RELAX, this is nothing to panic about.