water temp gauge sensor placing.

[TurfBurn]

you can tap into the signal at the ecu coming off of the sensor. its what i did with all of my gauges except for the oil pressure on the first gen, BUT MAKE SURE ITS THE ECU side. like as close to the ecu as possible, or its not as accurate

That's NOT a good way to do it... depending on the internals of the gauge he is using it can both give a bad reading on the gauge itself, but also can screw up the ECU and cause it to read water temps inaccurately...

The stock ECU uses voltage measurement based on current etc... if you add or subtract resistance to the circuit by going in series or parallel you alter that voltage and it messes up the readings... I don't recommend doing it as such as the implications are not completely known and it will vary gauge to gauge.

 

[Salmon_Rob]

if tap it in, and just draw off the signal not only do you not disrupt the signal, but you get a far more accurate reading.

 

[TurfBurn]

if tap it in, and just draw off the signal not only do you not disrupt the signal, but you get a far more accurate reading.

I don't know how you could get a "more accurate reading" unless you are assuming that the sensor itself is more accurate... and unless you have data sheets comparing the sensors you have no way to ascertain which sensor is indeed more accurate.

Also based on what do you assume that the signal is not affected? Have you put an oscilliscope or a calibrated voltmeter on it to verify it? Do you know the internal schematics of both the ECU and the gauge being used to ensure that there is no adverse affects? Or you are assuming some temperature differential between that location and a location in that same manifold or in the heater hose... but that differential should not exceed 5 degrees... and the gauges aren't accurate or precise enough to even yield that visually.

I'm an electrical engineer and I do control systems for a living... I also know from the work I've done for NSN that sharing resistor based sensors on the FS motors is a BAD idea typically.

Just because it "works" doesn't mean it isn't disrupting the signal etc. I haven't personally directly checked doing this on that sensor (I checked it on the TPS with the Microtech etc) so it may indeed be ok.. but before someone recommends something to someone that could cause adverse affects to their car and motor, I'd be damn sure I have proof to back it up before I make such a suggestion... and "it works for me" isn't proof enough... as "it works for me" led people to believe they could run 17 psi on stock internals too until motors started dropping like flies.

 

[FL_PR5]

ha true. well i just got back from school and asked my friend the same thing. he also mentioned about tapping into the original wire and then just running the gauges wire to from that instead of messing with installing the sensor. but hey, i might do that T, so where would i find that. i think i saw that on this site before but i cant remember where.

 

[FL_PR5]

ok, just got back from topping off car and a nice lil 2 gallon tank as back up from my gas station...only $2.67 so how could i pass it up exspecially with this town usually being out of gas.

anyways back to story,
i take it that doing the connection to the stock line is a bad idea and i'm better off doing a T or somehow getting my new gauge wire on there. only if i knew where to find that damn T (evil)

 

[Dexter]

if tap it in, and just draw off the signal not only do you not disrupt the signal, but you get a far more accurate reading.

?!

Explain how you get a more accurate reading if the sensor youre using isn't even designed to work with the gauge?

There is a reason why you need to use a sender...

 

[TurfBurn]

ok, just got back from topping off car and a nice lil 2 gallon tank as back up from my gas station...only $2.67 so how could i pass it up exspecially with this town usually being out of gas.

anyways back to story,
i take it that doing the connection to the stock line is a bad idea and i'm better off doing a T or somehow getting my new gauge wire on there. only if i knew where to find that damn T (evil)

Well, it sounds like people do that tap somewhat often... I'm just hesitant to do that as I know how those signals are read typically and how easy it is to screw them up.. keep in mind your water temp is one of the largest factors in determining your injector time in your car right after the MAF reading...

Any hardware store, or Lowe's, or Home Depot will carry the brass fittings you need to do it... I won't be home tonight at all so I can't take pictures of mine to show you... if I could remember the size it would be a lot easier... but if you measure the inside of that hose and then compare that with the oustide of the brass pieces you'll see easily what you need to do.

 

[aMaff]

just remember, if you can't duck it................................ (mj)

 

[TurfBurn]

handrill and bit, teflon tape, 1/4NPT pipe tap for about 5 bucks and about 1 hour of your time and you'd be done with this...

 

[FL_PR5]

haha i just dont want to drill because i dont want to mess it up. i dont want to miss the wrong spot, go in at an angle, or get shavings in my block or even ruin my head. i just dont want to mess up basically and ruin my engine by drilling in the wrong spot and messing up threads.
but with that T, i would assume its under $10 and a snip of the hose and some fittings and then brace it with some tightening screw thingys, forgot what they're called, and i'm done. then run the wire through firewall and to gauge and project is done.

 

[TurfBurn]

Yeah.. I meant to take the manifold off the car when doing it.. definitely don't recommend drilling with it on the head... but yes the T is quicker and simpler in some ways and less risky! Aluminum isn't always pleasant to tap.

 

[FL_PR5]

alright i found one on-line from this site. take a look-see:

but i need to find out one thing before i order: is it the 30, 34, or 36mm?

i need to measure this baby. but only if you lived on the panhandle of FL and i would pay you to tap my block for me since i am afraid of ruinning it. (shady) but do you think that this would give me a good enough reading of it? like is the water going into the engine from this tube or leaving it? and i would assume this would be placed on the black radiator hose that leads right into the block near the stock water temp sensor.

 

[FL_PR5]

found it at this site:

here

that is for the greddy. they also have black in HKS with also a 38mm.

 

[TurfBurn]

those are way too expensive!! they run like 20-30 some bucks..... and I think the sizes are wrong... It's really honestly only like a 3/4" internal diameter hose...

I know I have one there, and some other people do as well... it's good enough for the gauge I'm sure... you only need to know the rough temperatures based on the gauge... 180-210 is ok/normal... get above about 220 and you are getting dangerous.. 250/260 and I'd make sure you have a savings for new pistons/block.

 

[TurfBurn]

if you wait until tomorrow night I can take measurements and post pictures for you...

 

[FL_PR5]

alright thats fine. i can wait for pics. i measured the inside of the sensor so i could get the measurements. those millimeters dont sound right. i got like 8mm out of 1cm. here are some pics. i'm not sure how they got those numbers. i also found there is -27 on the gauge sensor.

i measured the inside of the sensor. and got those readings. so i dont know what size that would be on the greddy temp adapter. and yea, that is higher than i thought. but i found they are having labor day savings for 20 bucks so thats only 3 dollars right there.

 

[TurfBurn]

the sensor itself is 1/8NPT which is close to about 3/8" diameter and is about .405" .. but the therads are technically 1/8-27 NPT. and I thin the hose size would work out to like 18-25mm roughly for the inner diameter of that hose.

 

[FL_PR5]

so then what greddy adapter would i use for that? 30mm? i dont see anything smaller. damn, i better find a one or a bigger one so i could use the bigger adapter that came with the sensor in those pics. all these numbers

edit:* o i just caught it. is 30, 34, and 36 the size of the mian blue part for the radiator hose to connect to? and are the sensor fittings all universal so i dont have to worry about those not fitting?

 

[TurfBurn]

so then what greddy adapter would i use for that? 30mm? i dont see anything smaller. damn, i better find a one or a bigger one so i could use the bigger adapter that came with the sensor in those pics. all these numbers

edit:* o i just caught it. is 30, 34, and 36 the size of the mian blue part for the radiator hose to connect to? and are the sensor fittings all universal so i dont have to worry about those not fitting?

well they intend those adapters to go in the upper radiator hose which also is a workable option... just not as attractive as it can't be "hidden" at all... that's why the large sizes... as far as the sensor being universal... most gauges use 1/8 NPT.. but it's not universal for stock sensors as those vary from 1/8" to weird metric sizes and other stuff that gets a lot bigger typically...

I'll check it all tomorrow evening and I'll get you everything you need to decide what to do.

Later.

 

[FL_PR5]

alright thanks man. you have been more than helpfull. you are awesome haha (mj)

i dont really care about the attractivity of it since it is under my hood and if i want i can possibly turn it upside down so that it is less noticable. i dont mind paying that much for it if it makes it easier and does the same job as the stock one. plus it would help in the Florida sun (drive) i just want something quick and easy and i believe this is it. i'll ttyl then.

thanks,
-bob.