whitediamond642

I'm upgrading gauges to some nicer VEI gauges but need a little help. I have room for 3 total and two spots are taken by a boost and AEM wideband A/F. I can get a dual sensor that has oil pressure and oil temp or oil pressure and water temp.

My question is whether the stock water temp is reliable enough in my 94 accord to go with the oil pres/temp combo? I have a turboed h22 swap and drive pretty aggressively on the street and plan on some track days every now and again. Let me know what everyone thinks. Thanks in advance for any advice.

SovXietday

Stock water temp is useless, you really don't need oil temp as much as you're going to want water temp in your car.

Joseph Davis

If everything works right the stock coolant temp gauge doesn't move much 160-205 degrees F, barely moves 205-210, and swings like hell past that point even off of 1-2 degree increases in temp.

The problem with the stock temp gauge is a slave to your ground system. If you have any cooling system or exterior block corrosion or painting, old wiring, etc, your readings are thrown off. Which is really a nonissue since 98% of aftermarket temp gauges I've seen are incorrectly wired/grounded and read incorrectly.

Blah blah blah, just stay stock.

boost4life

wat do you mean by wired incorrectly how can this be prevented

Joseph Davis

Here's the biggest problems I run into:

- The alternator output is the only power in the system. The engine block, as close as possible to the ECU sensor ground, is the only ground point. Clean remotely located power and ground distribution blocks are fine but they have to be mechanically and electrically sound as well as environmentally shielded. The ground and power distribution system is a maintainence item, I clean all the ground paths every 2-3 oil changes. If the car is clean it's as easy as loosening and retightening 2-5 bolts. Tunes do "change" if the electrical points are compromised.

- I see a lot of problems with people using the unibody as a ground point. There's a reason why the factory fuel pump wiring puts out 13.8-14 volts and only passes 10 volts across the pump... at idle, I assure you it's worse as electrical load increases and the poor electrical path of the unibody increases in resistance as it's expected to drop more current. Do not ground sensors, gauges, electronic equipment, ground points for battery relocations, etc to the unibody. I don't care if Honda did it from the factory, Honda sells a disposable line of econoboxes they only warrantied for 3-5 years they don't have to live with it in a performance applications.

- Corrosion, paint, etc, on the engine and trans. Honda sticking the ECU ground on the thermostat housing wasn't the brightest move since that area is prone to corrosion. I've seen widebands grounded on a trans bracket (where one of the factory chassis to drivetrain grounds was) on a painted driveline that skewed up to 2 AFR points when compared to one grounded at the thermostat housing. I see that with anything that has ground problems, BTW, add it to your bag of tricks.

- Rotted or hacked engine harnesses. Hacked is self explanitory if you've ever had to bat clean up on wiring messes; see also: wiring tucks aka wiring *****. ED chassis wiring is officially a total loss, short of the garage stored cars the majority of harnesses are so damaged by age and the elements I refuse to tune them until a new OEM or OBD1+ harness gets grafted onto the vehicle, or the vehicle owner agrees to pay me even if the car doesn't run correctly or last five minutes. Look for blue-green corrosion or dull oxidation on exposed bits of wire - exposed because the vinyl wire sheath is old and brittle. There's some chemical reaction with the glue on the black tape used from the factory that takes 10+ years to manifest, the wiring sheath that isn't exposed will be gooey and of variable brittleness, if you wipe the goo off it becomes brittle within a month or two.

As a tuner I see a number of cars that are "dirty tunes," as I like to call them, where the car doesn't behave the way it should. These cars are not as adjustable as they should be, plug readings show soot where the car should be burning clean despite setting and resetting lambda offset at multiple load points, misc glitches, etc. There's such a craze for the Honduh stuff a lot of cars that should be scrapped are being built instead, and it's more than just cosmetic issues. It gets pretty crazy!

quicksilver1689

alot of guages operate like that, guage barely moves like joseph said between 160-205, basically its for the customer, they like guages, being able to look at things, they might freak out if they saw it fluctuating back in forth in real time, makes them happy, keeps the techs happy so they dont have to explain to customers that nothing is wrong with the car, kinda like an idiot light guage, nothing really happens unless your temps really skyrocket to the point of overheating.

yeha joseph is right, computer goes off resistance which changes voltage, with large voltage drops, high resistance which comes with "dirty" connections values the computer see's/calculates are not what they are.

Dunc

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boost4life &raquo;</TD></TR><TR><TD CLASS="quote">wat do you mean by wired incorrectly how can this be prevented</TD></TR></TABLE>

As said the stock one is a POS to put it bluntly. This is prevented by not using the electrical water temp gauges. Use a mechanical water temp gauge.

Joseph Davis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dunc &raquo;</TD></TR><TR><TD CLASS="quote">As said the stock one is a POS to put it bluntly. This is prevented by not using the electrical water temp gauges. Use a mechanical water temp gauge.</TD></TR></TABLE>

Being a digital kid that is something I have zero experience with. All my $0.02 is based off of electrical sensors I can log.

SovXietday

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dunc &raquo;</TD></TR><TR><TD CLASS="quote">

As said the stock one is a POS to put it bluntly. This is prevented by not using the electrical water temp gauges. Use a mechanical water temp gauge.</TD></TR></TABLE>

This may just be me but I'm not all about routing 200* coolant into my cabin thank you very much! I'll stick with electrical and just do my best to ground them well.

Damnit JD you make me want to go and rewire all my gauges/wideband.

Joseph Davis

If you're building the car from scratch it's something you should do anyway, given the high tone **** $bling$ builds I see posted here.

If your plugs look clean, the car runs great and makes great power, just shift important sensor grounds close to the thermostat housing area and don't worry about it.

Crx Jimmy

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SovXietday &raquo;</TD></TR><TR><TD CLASS="quote">

This may just be me but I'm not all about routing 200* coolant into my cabin thank you very much! I'll stick with electrical and just do my best to ground them well.

Damnit JD you make me want to go and rewire all my gauges/wideband. </TD></TR></TABLE>

You already have 200 degree coolant routed inside your car! its called a heater core
Also a mechanical water temp gauge does NOT have coolant going through any line! The probe goes in the coolant flow and the wire is filled with some kind of gas/liquid that moves the gauge.

blinx9900

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SovXietday &raquo;</TD></TR><TR><TD CLASS="quote">

Damnit JD you make me want to go and rewire all my gauges/wideband. </TD></TR></TABLE>

x2

Dunc

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Crx Jimmy &raquo;</TD></TR><TR><TD CLASS="quote">You already have 200 degree coolant routed inside your car! its called a heater core
Also a mechanical water temp gauge does NOT have coolant going through any line! The probe goes in the coolant flow and the wire is filled with some kind of gas/liquid that moves the gauge. </TD></TR></TABLE>

^^^Less typing I have to do, thanks

supergenius

Big guage power lines arnt going to do **** if there is not sufficent ground... Let alone the noise that can be created by ground potential issues ... (loops, etc. which can cause FUN FUN times)

Re wired both my fuel pumps using relays and power/ground from the bat. Same with the WBO2. Guages have there own discrete circuit as well...

HamiltonRex

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Joseph Davis &raquo;</TD></TR><TR><TD CLASS="quote"> I assure you it's worse as electrical load increases and the poor electrical path of the unibody increases in resistance as it's expected to drop more current. </TD></TR></TABLE>

Im not saying your wrong with your other statements, you are a smart guy and i enjoy reading your posts.

But the comment above bothers me, clearly you have no knowledge (or very limited) Of Georges Law, and have never had any education on basic theory of electricity.

Resistance is typically a fixed number, unless of course something happens and the connection becomes corroded etc, but resistance DOES NOT change as current increases.

Remember, current is the speed in which the electrons are flowing, Voltage is the force that pushes them, or a difference in potential EMF, voltage DOES NOT flow, current does, and current does NOT DROP, Voltage Drops across a load that is, which is why battery voltage is say ~12V (lets go according to theory here, 6 cells, 2 volts per cell), and you have ~10V across the pump, you have a voltage drop of 2volts across the unibody, you could measure from the positive battery terminal, to the positive connection on the fuel pump to actually measure this.

I understand what your trying to explain though, the unibody is a poor conductor and as current increases there is a greater voltage drop, beings why you said at idle there is ~10V across the pump, and probably less as more load is added, since you have a greater voltage drop with more current flowing with a fixed resistance.

See what you can learn about what George had to say, and by George i mean Mr. Ohm

Think of it like this for an example on the fuel pump. I will use generic values to make it clear to everyone else what high resistance values can do.

Ok.. You have a 12V power source, and 3 devices wired in parallel, to eachother and the source, all devices are very near eachother, so we will say between them the wire has a very low resistance and not worth worrying about.

But all 3 devices are 50ft from the source, so we have to consider the voltage drop of the conductors suppling the power.

Each device has a FIXED resistance of say 4 ohms, so @ 12V they will drap 3 amps a piece, correct?

Now, say the wire has a resistance of... 0.3ohms (typical value), on the negative and positive.

Now, if device 1 is drawing 3 amps, you will have 3 amps flowing though each piece of the wire supply the current, on each piece there will be a voltage drop of 0.9Volts, now at that first device you now only have 10.2Volts, as you increase the load, and turn on devices 2 and 3, you add 6 amps flowing though the wire for a total of 9amps, the resistance of the wire stays the same but now you have a drop across each piece of that wire of 2.7volts, and at each device you only have 6.6volts.

As your connections get corroded and increase in resistance you have a greater voltage drop which causes the effects listed by who im quoting.

(**Remember, these electrical items have a fixed resistance, and depending on how much voltage they are getting will effect the current that they draw based on Ohms Law, so my example is off slightly i just did it to kind of give people an idea on how it can effect things, because when piece 1 is only getting 10.2 volts and it has a fixed resistance of 4 ohms, it wont be drawing 3 amps anymore, i just dont want to make it too complicated for everyone to understand).


So its important to have good wiring people! Dont hack up things, when you do a battery relocate DONT use the unibody in the back and just use a bolt and nut and bolt your ground strap there, its not sufficent IMO.

Anyways.




Modified by HamiltonRex at 1:55 PM 2/6/2008

Joseph Davis

No, I have both knowledge and education. You might have some of those, too, but I can tell you what you don't have that I do: experience.

If you want to nitpick at me for translating technical theory into the vernacular for laymen in a manner that you disagree with, then let me turn the tables on you:

No, completely wrong, current is the amount of charge, in the terms which I was describing you need to familiarise yourself with current density across a fixed diameter of wire and it's relationship to resistance. Further, I can drop a current just like I can drop a mass, although it's not the common jargon used to describe differing voltage levels in a circuit. Get over it. The average gearhead found in this and other forums doesn't know the jargon isn't correct in EE circles and finds th example useful, and the average me who sleeps less than the average meth head shouldn't be taken to task being erratic and jumbling terms.

The speed of an electrical charge is that of light, modified by the propigation coefficient of the medium it transfers through. I know this like the back of my hand; half the people in my Digital Communications class last semester failed. I took the week before Finals off to go to PRI in Orlando, and made President's List for the semester.


Yes, we are talking about varying resistance as electrical load goes up in a corroded, etc, unibody. If you haven't noticed, electrical gremlins vary - like resistance - with temperature, and a bad ground (or other electrical) connection will become warm and gain in resistance. Any shadetree mechanic has noticed this... wiring problem? Blowing fuses? Why is this wire warm to the touch?

I currently have a Volvo in the driveway that develops 1-4 volts across the eyelet of it's ECU sensor ground on the IM, and becomes hot to the touch if the vehicle is run under load for any length of time. The problem isn't eyelet to IM contact but corrosion between wire strands and eyelet, and I would have fixed it by now but the cheap butane soldering iron I own can't melt solder on cold days. So, since it's still here as a learning tool for you in APPLIED theory, I recommend you make the 1200 mile trip so I can teach you a thing or two. I'll show you the TSB on the problem, and we can discuss what Volvo dealer mechanics have known for over 25 years.

I'm fairly well aware of how a voltage divider works, especially when one leg of it is a dynamic resistance - there was circa '02 a kid running around this forum and on pgmfi who used a potentiometer (as a fixed resistance, set once and forget) to perform an AFC hack on a MAP sensor (dynamic resistance) circuit. I delineated the problem of the signal skewing across the MAP sensor's operating range well enough five years ago to rest on it, it's searchable on this forum and pgmfi if you care to check my grasp of basics six years ago.

HamiltonRex

Your right, i can guarantee you have more experience then i do, i have limited training and knowledge in electronics specifically, since that isn't the field i specialize in.


No, Current is not the amount of charge, current is the speed at which the electrons are flowing, and they certainly dont flow at the speed of light!

If the conductor gets warm, because of a bad connection, there is resistance at the connection itself, causing the heat... This is again fixed, until it is cleaned, or gets worse, the heat in the conductor itself does not cause yet another increase in resistance... Well it does, but its very minimal and will not yield any significant effect in the circuit (good or bad).

Lets take a look at the resistances of copper wire at different temperatures. We will use 24 ga, since its a common size on automobiles for the types of wiring were discussing.

@ 20 deg C, (68F) a piece of 1000ft long conductor of 24AWG has a resistance of 25.7 Ohms, and at 75 deg C (167F) its resistance is 31.2 Ohms. Again, i highly doubt that any single piece of copper conductor used in our auto's is 1000ft long, so lets not worry about the temperature of a conductor increasing causing added resistance, the effects are minimal, lets worry more about the added resistance of the actual corroded terminal/connection itself.

The reason it becomes hot as the vehicle runs for a period of time isn't because of the increased load, its just because it takes time to heat up, it takes time for the molecules to move faster, if you put a pot of water on a stove, the stove burner heat is the same, but the water takes time to heat up, much like the conductor, the water dose not take time to heat up because the heat has to be turned up. Other then that i dont understand the point of the comment? Sure you found the problem but you cant fix it, i guess thats it?


I never doubted the fact that you were knowledgeable with simple electronic circuits. I just dont like your terminology that you used to describe things.. sure you know exactly what YOU mean, but when others read it that kinda know abit about something, but do however use proper terminology, it confused the hell out of them, but who cares really?

Joseph Davis

Electromagnetic waves don't travel at the speed of light on this planet, there is a propagation coefficient of less than 1 attached to all communications shy of passage through a vacuum. As far as the rate at which one electron travels... pfft, I meant the propagation rate and you know it so stop bending words (that's my job!), electricity passes through a conductor at the speed of light modified (reduced) by propagation coefficient. For copper wire a little over 2/3rds lightspeed.

This is also totally off subject.


The resistive or conductive properties of the wire are not the matter at hand, so there's no point in even looking at it.

The matter at hand is the corroded connections which do become hot, and do change resistance dramatically. Again, I refer you to the manner in which electric/ground problems change across operating temperatures whether from being attached to the engine or from generating their own heat (main relay, bad connection at baterry or fusebox, perfect examples). This is not a lab or a clearly defined mathematical equation on a chalk board, it is the real world and is a scenario that is to be avoided as you cannot correctly engineer variable levels of naturally occurring corrosion.

The engineering solution is to replace the wiring, not quantify the nature of the loss across it. All the things you are taught are derived from ivory tower lab work performed with the intent of ignoring or minimising the influence of the real world outside as it is chaos and can not be controlled. As such ideal modelling of electrical circuits have very little to do with what's going on in the real world, and any ground path through corrosion changes resistance like the bizzaro world version of a varistor.

I operate in the real world, and there are applications as a voodou technician where this knowledge is freaking handy when diagnosing problems.


Increased load generates increased heat, increased rate of heat generation.

Well, you and I care, apparently.

HamiltonRex

ok, im tired. game over.