Oil Pressure, Fuel Pressure, and Temp Gauges.

Coop

Member
:
2002 Mazda Protege5
I want to go boosted but first I'd like to have some engine gauges so I can keep a closer eye on what's going on under the hood. Suggestions, additional info and whatever else you'd like to throw my way would be appreciated. Links to a write up I overlooked would be even better. Boost gauge will be added later as well.

Thanks,

-Coop
 
Boost and wideband are most imortant, followed by oil preassure oil temp water temp. Any others arent hugely important. Wide band is most expensive i would get that first
 
A good installation how to for oil temp and pressure can be found here:

http://www.mazdas247.com/forum/show...Installed-(Oil-Pressure-amp-Temp)-on-Protege5

I just did an oil temp and pressure gauge, with an analog clock, from speedhut.com last week. Installation was way easier than i expected. I ordered the oil filter sandwich adapter from crossover auto, also. I've narrowed down a problem with the clock, but its being replaced for free (it loses accuracy considerable when illuminated) by speedhut.

here is a pic of the test fitment before they were hooked up. I know they're not straight, I was only trying to see how well the single DIN pod fit in my dash. The pod is from ESE tuning iirc; its made for Mark IV Jetta's/golf/GTi's...and was only $17 shipped. Its not a hugely perfect fit, but snaps in well and is stable with my nearly solid engine mounts.

https://docs.google.com/file/d/0B9wG_iZEqPQNZGJKOFo2RFdZeGc/edit?usp=sharing

https://docs.google.com/file/d/0B9wG_iZEqPQNYlNoN1FyRFhMbW8/edit?usp=sharing

My only advice would be...whatever gauges you decide, try to keep all of them the same brand. Not sure how other gauges compare, but speed hut sends all your gauges as a kit...the kit includes all necessary sensors, and a fabricated loom that connects to ALL the gauges you bought. So, for the dash wiring, you only need to tap one switched 12v power line, and anchor one ground line. You also then tap one illumination line off the dimmer switch, and a ground line for the lighting...all your gauges then snap into that loom...you don't have to wire each gauge individually...which was really nice imo. You can also remove them in seconds because of this.

In my case, the sensor wiring was just as easy...but i didn't do a boost gauge or AFR...and i've always had a preference for oil temp over water temp...oil is the one that is more critical...water temp is important, but any failure that results in water leaving the system...will give false cool readings from a real time water temp.
 
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Let me ask a question I've always wondered about oil pressure...do you see any significant data from that gauge? Hypothetically, if you saw your pressure drop, it's going to be quickly and before you can even get off to the side of the road, you've spin a rod bearing or worse. The stock idiot light conveys the same information...pressure too low. My understanding is that low oil pressure is more of a catastrophic failure. Your gauge either reads good pressure or no pressure, and in the latter case, who cares whether the light tells you or the gauge...it's too late anyway.

I could be way off base on this, and if you want or have an oil pressure gauge, that's great, but I have always wondered if it is really helpful at all.
 
I assume that a proper oil pressure gauge comes with a replacement sensor with it. I just got a new OEM oil pressure "sensor" in the mail yesterday and it is just a switch and even that switch is rated for 3-9 PSI, so it may not turn my idiot light on until the oil pressure is as low as 3 psi. A proper gauge should come with an actual sensor that reads the real time oil pressure data to send to the gauge.

Perhaps I shoulda looked into a different replacement oil pressure "switch" that has a higher psi range to air on the side of caution but I didn't think of that till just now. The idiot light might flash at idle with thin oil but I would know why,.... Oh well too late now.
 
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If you dont know what a wideband is you need to do alot of research for tuning

And an oil preassure gauge is for monitoring any preassure drops which would indicate a leak or dying oil pump. Iirc theres some that will even data log preassure levels and set up an alarm of somesort if its out of its normal range, but i guess that would be in the standalone and ive only read a little bit about it
 
I am running Blitz DC electronic Steppper gauges for Oil temp and oil Pressure.
They have their own sending units (to go into a sandwitch plate) and allow for some recording, playback, Peak alarm sets, and a Peak hold (shows you the peak over the trip).
super accurate, and once installed it becomes very apparent as to why you should have oil pressure gauge. doesn't just apple for under pressure btw... also applies for overpressure (if the valve fails).
 
If you dont know what a wideband is you need to do alot of research for tuning

And an oil pressure gauge is for monitoring any pressure drops which would indicate a leak or dying oil pump. Iirc theres some that will even data log preassure levels and set up an alarm of somesort if its out of its normal range, but i guess that would be in the standalone and ive only read a little bit about it
yea i didnt know what it was and didnt think i needed it being all im doing is adding a stock msp setup to my p5. i didnt think i needed to tune it either cuz according to wiki the msp and p5 fs engines are identical internally and externally with the exception of a bolted on turbo system.Which is what i thought i was gonna do just bolt n go.
 
Let me ask a question I've always wondered about oil pressure...do you see any significant data from that gauge? Hypothetically, if you saw your pressure drop, it's going to be quickly and before you can even get off to the side of the road, you've spin a rod bearing or worse. The stock idiot light conveys the same information...pressure too low. My understanding is that low oil pressure is more of a catastrophic failure. Your gauge either reads good pressure or no pressure, and in the latter case, who cares whether the light tells you or the gauge...it's too late anyway.

I could be way off base on this, and if you want or have an oil pressure gauge, that's great, but I have always wondered if it is really helpful at all.

You're mostly correct about a significant drop in pressure; that usually means its over...but, especially in these cars, you'd be very surprised how all over the place the oil pressure is under different conditions...

After some pretty hard sustained driving, many report pressure being only around 12psi idle...that is STILL higher than what will tick the oil light in the dash, yet is dangerously low...and probably a time to know when to back off to help prevent major damage...

and with an oil temp gauge, you can start to get an idea of how much punishment you can give the engine...or more particularly, the engine...low oil pressure and high oil temp are usually a married couple...

but yeah, you make a good point...there isn't really any gauge thats going to give you future proofing as far as engine damage goes...any of them, water, oil, afr, etc...are just relaying real time stuff...and if the 'real time' is showing something bad, you probably broke something...even AFR...its needed for tuning for sure...but if you're full load wot in 3rd gear boosting some huge psi with a big turbo...and you see AFR start to dance around >13:1...grenade...
 
After some pretty hard sustained driving, many report pressure being only around 12psi idle...that is STILL higher than what will tick the oil light in the dash, yet is dangerously low...and probably a time to know when to back off to help prevent major damage...

and with an oil temp gauge, you can start to get an idea of how much punishment you can give the engine...or more particularly, the engine...low oil pressure and high oil temp are usually a married couple...

So can anyone direct me to an OEM style oil pressure "switch" that will screw in where my pressure "sensor" is, that has a safer kick out PSI, while I consider the oil temp/pressure gauges.

That installation of yours looks damn fine installshield. I even have an aftermarket head unit to consider installing to make room for the gauges, so it's just the cost of your type of gauges and related sensors to think about.

I haven't installed my new oil pressure switch yet so finding a different one that is safer will buy me some time while I do more study on your install (awesome how-to link by the way).
 
So can anyone direct me to an OEM style oil pressure "switch" that will screw in where my pressure "sensor" is, that has a safer kick out PSI, while I consider the oil temp/pressure gauges.

That installation of yours looks damn fine installshield. I even have an aftermarket head unit to consider installing to make room for the gauges, so it's just the cost of your type of gauges and related sensors to think about.

I haven't installed my new oil pressure switch yet so finding a different one that is safer will buy me some time while I do more study on your install (awesome how-to link by the way).

Most sensors will have the same size hole, but removing the stock one will result in a Red Light on the dash.

You can install a Y or Tee Fitting to run both, or install what is called a "Sand witch Plate" which will also let you run an oil cooler in the future.






No It does not cover anything usefull....

Reading 3 pages of that is not going to teack or help anything..

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You're mostly correct about a significant drop in pressure; that usually means its over...but, especially in these cars, you'd be very surprised how all over the place the oil pressure is under different conditions...

After some pretty hard sustained driving, many report pressure being only around 12psi idle...that is STILL higher than what will tick the oil light in the dash, yet is dangerously low...and probably a time to know when to back off to help prevent major damage...

and with an oil temp gauge, you can start to get an idea of how much punishment you can give the engine...or more particularly, the engine...low oil pressure and high oil temp are usually a married couple...

but yeah, you make a good point...there isn't really any gauge thats going to give you future proofing as far as engine damage goes...any of them, water, oil, afr, etc...are just relaying real time stuff...and if the 'real time' is showing something bad, you probably broke something...even AFR...its needed for tuning for sure...but if you're full load wot in 3rd gear boosting some huge psi with a big turbo...and you see AFR start to dance around >13:1...grenade...

This answers my question..."are there circumstances where an oil pressure gauge would give you helpful information in time to take action?" Thanks man...I suppose my next question is, what is the safe range of oil pressure? And what pressure trips the idiot light?
 
^What he said, maybe someone can give us a safer pressure number to use for a non-OEM pressure switch. I don't mind some false readings,... may be set to 15 PSI minimum.

Does anyone know of anything that will screw into our engine where our pressure sensor is. Do you think a message to Rockauto would help ?? It's mostly thread diameter and pitch.

I know this won't help with overpressure but it should help alot with under pressure to give us more warning if the oil pump takes a poop.

(Hmmm maybe there is a sensor that is double switched for high and low limits,... but I'm probably just overthinking it again)


" And what pressure trips the idiot light? " My new OEM pressure switch is set to "3-9 PSI". That's friggen useless,... may as well not even have it connected.
 
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I haven't seen it in a while, but i vaguely remember the OE light coming on at anything below 9 psi...regardless of engine speed, load, etc...below 9psi, major problems will happen very quickly...so i've always felt that light is no better than the 'dummy' water temp our cars came with...it really only has 3 positions...cold, 'normal', and overheated...while it will slowly rise from cold to normal...most have reported it just shoots up to high very quickly, and the engine is already way too hot...I can't fully confirm that, luckily i've never overheated my engine yet.

the reading your oil pressure gauge gives, though, is a bit of a moving target depending on how you install it...If you T off the stock pressure sensor, you're not getting a completely accurate reading for pressure...a pressure sensor correlates 'loaded' pressure through electrical resistance...the more pressure that builds up in it, the more the resistance is changed, and the gauge moves according to that...T'ing off of a stock sensor, with another sensor, doesn't load the aftermarket sensor fully...so you'll get a consistently lower reading...

from what i've seen...this is what causes the ~12psi hot idle some guys see...I installed my aftermarket sensor in a sandwich plate (so its effectively reading oil pressure at the filter), which loads up the sensor after oil leaves the filter and moves back into the engine...oil pressure can't 'miss' the sensor when its installed in this location...and i've yet to drop below 19psi hot idle after some pretty hard running....So i'm going on 19psi as my 'normal' idle reading after a tough drive...with oil temps around 235 as well...under high revs, i regularly get over 70psi even fully heated...and keep pressure around 58 during sustained cruising at ~3100 rpm highway...

I'm in the middle of an on-going NA build...and i'll use these above figures to determine additional oiling needs in the future...personally, i'm not thrilled with even 19 psi at hot idle...i'd rather it be closer to 30psi...probably not necessary, as i'm lucky with very little city driving for the most part...but a 16v DOHC engine has a fair bit of moving parts that i'd like to keep washed with fresh oil very regularly...the less pressure, the less that happens...

So, if my pressure changes dramatically under any of those situations...i can make the upgrades accordingly...pressure dropping and temp rising through the summer as the build gets a little more aggressive, i'll have to look into an oil cooler...pressure begins to drop with temp not changing a whole lot, tolerances are truly giving in and/or my oil pump is wearing out...and i'll look into a coated Doc B pump or one of Ryan's new offerings...I'm interested in the changes to the numbers i've already recorded...and slight changes for the worse are still well above what the factory light calls 'bad'...so i feel like i have a better chance of replacing or upgrading before its too late because of it.

I went with the basic gauges offered, which i linked to on the first page...they do offer upgrades that included settable warning lights and tones...but its an engine with about 160k miles...i'll keep an eye on everything, but didn't see the need for going an extra $100 worth of dinging sounds and lights that are still just saying 'your engine died' haha...
 
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So i'm going on 19psi as my 'normal' idle reading after a tough drive...with oil temps around 235 as well...under high revs, i regularly get over 70psi even fully heated...and keep pressure around 58 during sustained cruising at ~3100 rpm highway...

That's the number I'm looking for,... I want to replace not t-off the pressure switch with one set to trigger at maybe between 20 and 25 psi then.

This is a picture of what I just received in the mail,... It has 3-9 PSI stamped on it.
That means it may not trigger until the PSI drops to as low as 3 PSI before it "switches" and turns on my idiot light.
I want to get something,... perhaps built for another vehicle,... that has something like 20-25 stamped on it.
I don't even know where the hell it goes yet,... I still have all my homework to do.
oilsensor_zps8e0768c4.jpg


I remember my 1983 GLC used to burn oil and if I forgot to top it up I had an interesting side effect of the sensor in that it would flicker when it was time to top up the oil again. I doubt that this car would do that for me but I'm hoping for a more useful reading from my idiot light.
I don't mind some "false" triggers cause by a low idle on a hot day.
 
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That's the number I'm looking for,... I want to replace not t-off the pressure switch with one set to trigger at maybe between 20 and 25 psi then.

This is a picture of what I just received in the mail,... It has 3-9 PSI stamped on it.
That means it may not trigger until the PSI drops to as low as 3 PSI before it "switches" and turns on my idiot light.
I want to get something,... perhaps built for another vehicle,... that has something like 20-25 stamped on it.
I don't even know where the hell it goes yet,... I still have all my homework to do.
oilsensor_zps8e0768c4.jpg

Well with a handful of stuff totalling around $5 at somewhere like radio shack, you could probably build a little pack of resistors to change that sensor entirely...but, you'll be mucking around with the factory wiring...so i'd build a little thing off of the stock line, between that new sensor...and see what happens...

as i mentioned earlier, its a resistive sensor...as pressure builds inside of it, the resistance changes...the ecu sees that, but doesn't care about additional pressure...its just triggered if resistance gets below/above a certain threshold...of which represents about 9psi of oil pressure, if what i read years ago is accurate...So i be that sensor is actually throwing all kinds of different readings out all the time, its just the computer doesn't give a s*** until its at a very specific measurement...

in either case, that isn't important...you could simply install the sensor and take resistance readings off of it...check it key on/engine off...see what its resistance is for zero pressure...then see it for idle...then see it for sustained higher revs...that'll give you a loose scale to go off of...as i'm not sure if higher pressure builds resistance, or reduces it...

depending on the scaling...you could then splice in a connector that adjusts and scales it differently, right?...See what the idle resistance is, and build a little connection that changes the resistance sent to the stock computer...so that at say whatever resistance is ~17psi (would be slightly different than hot idle)...the connector changes it to make the computer think its >9 psi...and the light comes on in your dash...

i'm no electrical engineer...but that shouldn't be that hard...
 
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The stock "sender", "sensor" is just a switch. There is no varying resistance inside,... It's just "on" or "off".
That's why your new install is so much better than what the rest of us are dealing with.

I am considering doing what you've done (awesome install by the way) but for the time being I just want a different switch.

That 3-9 PSI just says that the switch will short to ground at somewhere between 3 and 9 PSI,.... It's got such a bad tolerance that they can't even say exactly when it will switch on and short the circuit to ground and set off the idiot light.
 
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