Got my SUNPRO oil & volt gauges

[1991toyrolla]

Hello Folks, I finally got my SUNPRO volt & oil pressure gauges for my 1991 AE92. Thanks to the advice of toyotaspeed90 & eage8 I bought an electric oil pressure gauge. I decided to mount them in the space located under the a/c controls. I want to make a black plastic cover to go over the space with only the 2 gauges showing. They will be installed to the actual plastic cover.
I have 2 questions:

1) Where is the oil pressure sending sensor located?

2) Can it be wired so that the oil pressure gauge & the OEM "idiot" light both work or do I have to eliminate the original connection?
THANKS

[kcwa]

1991toyrolla...here is a post I made to your original thread:

The oil pressure gauge line should screw into where the current oil pressure sending sensor is on the engine. You can find it I think just forward of the oil filter. You would unscrew that, take it out, and replace it with the line to your new gauge.

Did the new oil pressure gauge come with a new sensor? ... or is the new gauge instructed to connect to the original sensor? If connecting to the original sensor it may be possible to wire them together, and if there is a new sensor it is probably unlikely.

[eage8]

Originally Posted by kcwa

1991toyrolla...here is a post I made to your original thread:

The oil pressure gauge line should screw into where the current oil pressure sending sensor is on the engine. You can find it I think just forward of the oil filter. You would unscrew that, take it out, and replace it with the line to your new gauge.

Did the new oil pressure gauge come with a new sensor? ... or is the new gauge instructed to connect to the original sensor? If connecting to the original sensor it may be possible to wire them together, and if there is a new sensor it is probably unlikely.

I'm pretty sure the stock sensor is digital (aka, it's either low pressure or not). The new sensor most likely isn't the same thread pattern. A lot of times you can find sandwich plates that go between the oil filter and the block that you can screw oil pressure senders into, I'm not sure if that would work that great on a corolla though due to the exhaust manifold.

take the stock sensor out and see if their the same thread pattern and go from there. That would be the easiest, but your light wouldn't work anymore.

[jmaz87]

i opted for mechanical gauges as they tend to be more accurate and show pressure loss immediately.

the block threads fit the fitting with no problems (eliminating oem sensor) i used copper tubing instead of the crappy plastic crap...

didn't you get a water temp sensor??? that's pretty important on the list of stuff you should be measuring lol

[toyotaspeed90]

Originally Posted by jmaz87

i opted for mechanical gauges as they tend to be more accurate and show pressure loss immediately.

that's actually not accurate......

how accurate a gauge is actually depends on it's margin of error -- be it for that specific gauge, that line of gauges, or the company as a whole. I have a friend (ex mr2 owner) who's job previously was gauge calibration, so I'm pretty aware of this stuff....

the fact that an electronic gauge is just that -- electronic, has nothing to do with it's accuracy. The only way it may be "inaccurate" would be if for some reason really resistant cable was used to where there's a voltage drop that far exceeds the margin of error that the gauge itself has (ie if the gauge has a 10% margin of error -- which most automotive gauges have somewhere around there -- then the cable would have to have 15-20% loss of voltage via resistance in order for it to be inaccurate).

that would be the same thing as saying that your map sensor isn't accurate because it doesn't have a vacuum line that plugs into your ecu that pushes a diaphram thus giving the ecu it's required information.....

[jmaz87]

i guess i should have worded things differently. i've "heard" that there is a minute delay in the reading to the actual gauge

i.e. your water pump stops and temps sky rocket... the mechanical sensor is driven directly via copper tube and would probably show a minute spike before the electric unit.

it's not a calibration issue it's a response thing and again i could be mis-informed...

your oil pan gasket starts spewing oil... the mechanical unit would immediately drop im pretty sure quicker if even only a second than the electrical unit takes to send a signal...

[toyotaspeed90]

Originally Posted by jmaz87

i guess i should have worded things differently. i've "heard" that there is a minute delay in the reading to the actual gauge

i.e. your water pump stops and temps sky rocket... the mechanical sensor is driven directly via copper tube and would probably show a minute spike before the electric unit.

it's not a calibration issue it's a response thing and again i could be mis-informed...

your oil pan gasket starts spewing oil... the mechanical unit would immediately drop im pretty sure quicker if even only a second than the electrical unit takes to send a signal...

I can see where you're going.... but you have to understand the accuracy of gauges to understand what sorts of variances you would see.

and the only way you'll see an instant loss of pressure is if just that -- you actually lose pressure.... an oil leak will only drop pressure once the oil level is too low for the pickup tube to supply enough oil to the pump to not create pressure.....

[1991toyrolla]

Hello All,

The electric oil pressure gauge & volt gauge have been installed. I used the sending unit that came with the oil gauge. What I would like to know is where to install the power wire to. Ground is obviously ground & ofcourse the wire for the sending unit goes to the sending unit on the engine.

I ask because the power source being used now (I don't know the source, the car is not with me at this time until about a week from now) may not be good. The needle fluctuates & sits at about 10 psi at normal operating temp when in drive at a stop light for example. It does go up under acceleration. Is it normal for this to fluctuate. I assume with a car that has only 34+ thousand miles it is not an engine problem.

BTW what is normal oil pressure at start up when it is cold?

Thanks

[eage8]

Originally Posted by 1991toyrolla

Hello All,

The electric oil pressure gauge & volt gauge have been installed. I used the sending unit that came with the oil gauge. What I would like to know is where to install the power wire to. Ground is obviously ground & ofcourse the wire for the sending unit goes to the sending unit on the engine.

I ask because the power source being used now (I don't know the source, the car is not with me at this time until about a week from now) may not be good. The needle fluctuates & sits at about 10 psi at normal operating temp when in drive at a stop light for example. It does go up under acceleration. Is it normal for this to fluctuate. I assume with a car that has only 34+ thousand miles it is not an engine problem.

BTW what is normal oil pressure at start up when it is cold?

Thanks

it's normal for it to be low at idle then raise when the rpms go up. the oil pump starts spinning faster which raises oil pressure. you also need more oil pressure because there is more stress on the engine.

10 psi seems a bit low to me though, I'll try to look in my factory service manual when I get home today for what it's supposed to be.

oil pressure when it's cold should be a good bit more than when it's hot.

a good power source is the cigarette lighter, just splice a wire off there and you're good to go.

[jmaz87]

yes you might have a PWR and ILL (dash light) wire so make sure u use the right power or u will only have pressure when the car lights are on lol...

When cold i usually see 40-50psi then 20-30 (no lower than 20psi ever!!!) once warm

when u rev under load ( in gear) you should see a considerable rise as the oil-pump speeds up with the motor it should stop at about 70psi (oem bypass valve spring is set around there)

what about water temp???
thats more likely to be important for you than anything else in case you over-heat or something...