My oil pressure gauge goes all the way up and stays there? wires backwards? not hooked up? bad guage? Oil level is too high even though it is so damn hard to tell with the dipstick they give us...

They are **** to begin with. Go aftermarket..

Sounds good are they easy to hook up come with instructions?

Cant complain about too much oil pressure...=) Unless its at idle..=)

It's all the time as soon as i start it up.

There's a spring on the back of the gauge that needs to be fixed. You'll have to remove the instrument cluster to fix it. Just be sure to remember the original position of the needle when the car is off.

take a pic of the cluster before you take it apart.



as for a aftermaket gauge, you will need a adaptor block

to go under the oil cooler to hook it up, unless you get

one that has the right threads to fit in where the OEM mazda

sender is.

A friend of mine said that the Greddy sender goes right into the stock hole, but I'm not too sure about that. Either the Racing Beat or the FC3S.org oil filter pedestal would be the best route to take.

if your not good with a wrench then get someone to help you, a stubby

10mm wrench makes the install of the pedestal easier.

First before you take things apart, when was the last time you changed your oil? how much oil did you put in? If you put too much it will cause you to read high oil pressure. Also what viscosity did you put in?



Once i added too much 20W50 and whenever i hit high revs the oil pres gauge will peg and iw ould get a warning light... too me 300 kms of driving for the oil to be used up some.



Btw the stock oil pressure gauge is not garabage. Why does everyone think everything on the car is garbage?

because they are dicks

the stock oil pressure gauge and sender are both garbage. fact.



http://pengaru.com/~swivel/cars/rx-7/ops/w_IMG_3221.JPG



do you want a schematic too? Or would you rather have the method of operation explained, it took us a long ass time to figure it out.

A real man could do it with a full-seized wrench. https://www.nopistons.com/forums/pub...>/rolleyes.gif

Pengs pulling out the big guns https://www.nopistons.com/forums/pub...IR#>/bigok.gif

I was just being a wise ass

I see no variation in readings from my stock gauge and

my mechanical aftermarket actually, but then again

mine still works and isnt pinned.

more like the big pics lol



seriously though, that sender is a complete disaster, there are others that have been used just like it in the past and even on some current cars and they are known for being shitty and unreliable.

Out of 6 FC's I've had, I had one go bad with the "pinned" problem, but I was able to fix it. I think that if you don't modify anything the car is happy. Mazda actually has a warning about installing CB radios in the car. They say that if you mess up you could also mess up the fuel injection system. I would assume that the same goes for an aftermarket stereo.

alright i stand corrected, i'm just speaking from experience, and out of all the rx7 owners in toronto, no one has said anything about their oil pressure senders failing.



I only speak from my own experience.

I really doubt that the sender is crap. I have the exact same sender (well, might be different resistance range) on my 4Runner, I have worked on and helped work on dozens of Toyota trucks, and have known hundreds of Toyota truck owners, and I have never heard of a bad sender unless it gets damaged. What *is* a weak spot is the unprotected and relatively weak wiring connector. On the trucks, it came with a plastic sheath that covered the connector and sender, and held them firmly together. I think that the weak connection could be a major cause of issues. I also wonder if the actual oil region on the block where the sender goes has issues...I had a case where there was some crud caught in there, my gauge would randomly go between zero pressure, pinned pressure, and correct pressure. I think there was something in that oil passage that was intermittantly blocking/unblocking the sender.



I don't doubt that the factory guage might very well be a weak link too.

The picture above is the internals of the sender on our fc's, it's a crude design, believe it or not, it's electro-thermo-mechanical. Thats right, the current flows through a heater element in the sender to bend a bimetallic strip which doubles as a switch. When the circuit is closed (bimetallic strip resting on a terminal slightly visible in the picture) the current flows through the heater wire, causing the strip to bend from the heat generated. When it bends enough to lift off the terminal, the circuit opens and it cools, straightening out eventually closing the circuit again. this process repeats itself the entire time the sender is functioning.



Now, the way oil pressure affects this thing, is the terminal on the bottom that the bimetallic strip rests on, moves when pressure changes. There is a plate which deflects with pressure at the base of the sender, this plate pushes the terminal up and down, this in turn changes the frequency at which the circuit will cycle.



So there you have it, the sender outputs a switching current crudely generated by something directly effected by temperature. The gauge side has a bimetallic strip/heater wire setup also, higher frequency == higher average voltage == more deflection of the bimetallic strip @ the gauge == higher pressure displayed. Ever wonder why the thing seems to respond slower when it's cold out?



You can imagine the confused look on my face when we discovered the wire wrapping that plate was a heater element inside the oil pressure sender, now I want to frame the part photographed above and hang it on the wall for the EE types to stare at for hours trying to figure out wtf it is / does, then laugh hysterically when reveal what it is.



BTW, thanks go to ikrazygluebrokenapexseals for contributing to the reverse engineering of this ridiculous thing.

When i shut the car off all the guages go to there bottom but the oil pressure gauge goes way down....

just replace the sender and gauge with a sane aftermarket one.



sometimes you can fix the stock one, but it really isnt worth the trouble.



I had a stock one get all fucked up kindof like you are describing, it would rest below 0 when the car was off but it would read really low too (not like yours), what happened on that one was the needle had shifted on the axle due to the wire going to the sender falling off and shorting to the chassis. When it shorted temporarily the needle pegged but the axle tried turning it further than it's limits, making it slide inside the needle so when it returned to 0 the needle was showing below 0. It also bent the pin that is on the bimetallic strip in the gauge due to trying to bend beyond the limits it was deisgned for, I ghetto fixed it but it still didnt work quite right and it now sits in the basement in a box somewhere after I learned just how junky the stock stuff was.



with your problem, it sounds like the wire going to the sender is shorted to ground, pegging the gauge when theres current, and it's shifted it just like mine. So you can probably find the short and fix that, but I fear your gauge is probably damaged due to the shorting causing the bimetallic strip to deflect too far bending the pin and turning the axle inside the needle. Check the wire @ the sender, if it's connected properly, pull it off and check for continuity through the sender (multimeter, continuity buzzer / resistance check, one wire on ground, other on the terminal of the sender) if you find there is continuity then your sender is shorting internally. Make sure you're doing this with the car off (0 psi), it should have no continuity with 0 psi (infinite resistance).



I hope you decide to just get something aftermarket though https://www.nopistons.com/forums/pub...IR#>/smile.png troubleshooting and solving the problem can be satisfying regardless if you're into that, just be aware the system you're trying to fix is a shoddy one when working perfectly.

Is there a guage/cluster kit you know of thats good for our cars?

guys i am browsing the 2nd gen site to learn some. i have a fd and where the stock oil sending unit goes, upper left side rear, the greddy elec unit does screw right in. dont know if it is the same but for what it's worth.

Thanks for the confirmation. https://www.nopistons.com/forums/pub...IR#>/bigok.gif

hey Peng- any idea how a aftermarket electronic oil gauge works?

the gauge or sender?



the sender is usually a simple electromechanical setup like your fuel level sender, variable resistor, lever driven by a plate that deflects from the pressure. Resistance changes with pressure, gauge displays basically the resulting voltage (sometimes translation is necessary when it's not a linear relationship). They wear out eventually (remember the hand controllers for slot cars? mine used to wear out eventually over the area the wiper covers most often, like a TPS) but they are more reliable and consistent throughout their lifespan.





the gauges can still use a bimetallic strip, others use (electro)magnetism, some are quite advanced and use microprocessors so you can calibrate em to senders that have a non-linear resistance:whatever relationship, whatever being pressure, fuel level, temperature, etc. You can also get a LED gauge which IMO is a better choice than any analog gauge that uses a bimetallic strip as a motor for the needle. Or the ultimate, an LCD connected to a microprocessor + analog to digital converter.



One of the nicest things from my point of view about a simple variable resistance sender is you can actually test it with a ohmmeter if you doubt your gauge, and alot of these senders have published resistance:psi (or whatever) tables online so you can confirm the real value with just the resistance reading, no gauge needed. You don't have this stupid heated element taking relatively large amounts of current to function as a sender either.

I see you have done the reasearch, it would be interesting to know

what methods each brand used. You are going to run some kind of

set up thru a computer with a LCD screen correct?

Yep, I am working on such a project, most of the data will be coming from the haltech e6k in already digital form, but there are still things like oil pressure and fuel level which the e6k knows nothing about. For those inputs I'm using a general purpose analog to digital converter just like the e6k itself uses for it's inputs, it connects up to the parallel port on the computer responsible for rendering the gauges on screen (and communicating with the e6k via the serial port).



The reason I had to look so far into the oil pressure sender is I tried using the stock one for the LCD gauge project, and that was a complete disaster given the design of the stock sender. Every other off-the-shelf sender I've bought and tested has been the more sane variable resistance type, I have yet to test the FD oil pressure sender which might be simlar to the FC one (ick) or might be 'normal', which would be nice since it's the correct japanese pipe thread type needed for our engines, eliminating the need for an adapter which is usually necessary with the off-the-shelf units (NPT).



I've actually got most the e6k stuff all hammered out, I intend to sell this as a product eventually but there have been some setbacks with other aspects, mostly hammering out hardware support for peoples laptops, particularly the graphics hardware. Laptops are a bit of a pain in the ass in the hardware support area. Feel free to PM me if you're interested in the e6k lcd gauges, I'm afraid it doesnt really help anyone with a mostly stock car who just wants some decent gauges though. The e6k is really needed to make it worthwhile at this time.

Im sure you also know the adaptor block gives you 2

places for a gauge, so one could be oil temp if you desired it.

yeah, theres also the bung in the oil pan for the stock sub-zero oil temp switch which you most likely don't use with the sub-zero cold start assist disabled, could install a sensor there, free port https://www.nopistons.com/forums/pub...IR#>/smile.png

damm your good