Using Resistors on the Sensors

fofish8601's picture

I thought this seemed like one of the easiest things to do, but I can't seem to get it right.

Do the higher resistor values, 10k, 25k etc., make the PCM/ECU see higher temps.
or is the lower value resistors 10 ohm, 100 ohm etc.?

I have the B2300 and I thought it needed a 5k on the CTS, since it is a Ford(mazda).
But I have cold start issues even at 10k on the CTS.
I was thinking of just keep going up on the values untill it starts better but am I going the wrong way?

ANY HELP?

Considering the lightbulb, Fish from Texas

Comments

Re: Using Resistors on the Sensors

Notsure's picture

Try using a small 15k pot and solder it in where the resistor would go. Adjust it as you see fit. Test it thouroughly to make sure you are free and clear. Then measure the resistance across the pot and that is the size resistor you should use. Or you can just leave the pot in there. Good luck brother.

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Re: Using Resistors on the Sensors

FUELMIZER's picture

HI i am not sure about resisitors outher than resistance sorry/// however some one else here does.. if i may ask a question about my cars say maf censor and if i added a resistor in parell with the ground wire.....is this gonna make it use less fuel.....my whole goal is to try get better fuel millage i have did this already to every censor i can get to that i think might help it lean out installed the o2 entender also....this seems to be the place for all the answers........tho old style cars i know about some little bit but these cars now days are a real problem to work around.... so hope fully we all learn here thanks

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Re: Using Resistors on the Sensors

E=mc2's picture

fofish8601 wrote:

But I have cold start issues even at 10k on the CTS.

I call that a result. Put a switch on it and enable it after you've driven 1/2 mile?

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Re: Using Resistors on the Sensors

FUELMIZER's picture

HI see for me these cars now days......it is totally unexplored territory..... i read even the hi paid auto tecks arent taught anything but how to check and replace any problem item like a bad o2 censor........unless they study it on their own time....sorry dont mean to be critical.............but ok i,ll take my time get all the effiency i can.....oh yes i know the hho system works........like i said i,ll turn it on after i get all the fuel system censors tweaked.......good luck to you thanks for the incouragement.

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Re: Using Resistors on the Sensors

qsiguy's picture

He means put a switch on your resistor and bypass it until the cars warmed up. That will eliminate your cold start issue. Also, I wouldn't wait until you figure out all your sensors before using the HHO. It's possible to get decent results from the HHO with only an EFIE installed. To make sense of your sensors you really need to first establish what the sensor is doing and how it changes based on temperature. I would check the resistance with your ohmmeter when the motor is cold and then start it and let it warm up and watch the reading. Does the resistance increase or decrease? This will tell you which direction you need to go with your resistor.

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Re: Using Resistors on the Sensors

FUELMIZER's picture

HI .... i might say this is new territory for me.. but yes i am beginning to get a grip on what you guys are talking abot... so yes at this present time am getting some inpressive results =D> with some inexpensive resistance....placed at before said locations........am sure happy some of you guys know about this automobile fuel effiency tips..ways to get more m p g ..........i have mentioned some of these tips to my friends here my home town welll they think i dreamming ....oh well huh.. oh another thing i have done replace the stock air filter with with say something less restrictive.....that alone helped immediately more m p g ...........so yes i were all have lots good tips posted here by the moderiator & you all see ya later don.... :D :? HI am back after lots driving mostly interstate 55, 65 m p r... so any way the car slould be getting its best at that constant speed .. my thoughts just a tad over 40 mpg....however it did better earlier on! strange huh.... so some where another fuel controll censor is comming into play...thought i had them all map,maf,iat .coolant temp censor, tps ........ the engine is tunned to peak performance...i am sure no problem there...soooo now back to nit picking......so until i can figure out whats going on the HHO system is disconnected.. so again hopefully it wont take all winter to check things out........any good suggestions thanks ............. fuelmizer HI am back now after long time......i have quit tinkering with this car fuel censors....just read justing the EFIE hope fully it has settel down to a deceint lean setting.. and getting ready to hook up the hho generiator...in theory should see some real millage ???? however also have learned not to get my hopes up #-o well 5-25-09 update with the EFIE alone the car fuel effiency has improved to my expections ..... =D> havent touched the cars fuel censors :)

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Re: Using Resistors on the Sensors

Raysp30's picture

I'm hoping to get a little help with this.

I've been thinking about doing this mod for about a month now (adding resistors to the AIT sensor). I know there's a signla wire to tap into, but I'm not sure which one. Also, I'm great with stuff like house wiring, but I've never done anything with pots and switches.

I want to hook up my AIT sensor to a SPDT switch (on/on) so I can use the AIT sensor when I want to and then switch to a pot when I want to change the resistance. How do I wire this?

If you can help me, I swear I'll have my fiance bake you cookies or something. Thanks.

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Re: Using Resistors on the Sensors

Notsure's picture

Well, as far as the IAT goes, I got rid of that resistor all together. Instead, I took the plastic air box out and blocked the incoming cool air from the fender well so the engine could actually breath warmer air. Then I simply moved the IAT sensor a bit closer to the radiator. NOT TOO CLOSE... :mrgreen:
This works great for me cause not only am I telling the car its getting nice warm air but it is actually getting it.

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Re: Using Resistors on the Sensors

qsiguy's picture

Raysp30 wrote:

I'm hoping to get a little help with this......

We're going to need some info to help. What kind of car? Do you have any diagrams of the electrical system? Typically, lowing the resistance of a temp sensor will effectively tell the receiver (ECU in this case) that the temperature is warmer. Higher resistance colder, lower resistance hotter. If you add resistance in series with the sensors output wire the ECU will assume colder air. To send a warmer air signal to the ECU you will need to wire a resistor in parallel with the AIT sensor. There will typically be a wire in and a wire out of the sensor. The new resistance, or POT, will go from the input to the output leads. If you can get your hands on a service manual for your vehicle it should tell you the specs for the sensors for testing. If you can locate it just get a thermometer and put it in water on the oven with the thermometer and measure the resistance across it while watching the temp. This way you can figure out that at 100*F ambient your sensor is at 1K ohms (example only), then at 120*F it's at 600 ohms, etc. Then you can decide how much resistance to add or subtract.

Here's a cool parallel resistance calculator. Enter the two values and it will show you what your output will be. For example, if the AIT sensor is at 1k and your pot is at 2.5K the ECU will see 714.29 ohms. As you lower the resistance of the pot the output will also lower. If both the AIT and your POT are at 1K the output will be 500 ohms. The formula is (R1xR2) / (R1+R2) = R3...R3 being the output resistance.

http://www.1728.com/resistrs.htm

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Re: Using Resistors on the Sensors

FUELMIZER's picture

HI ...i am full of questions today huh.& have i asked this question before what do you know about the vss...vehicle speed sensor any dealt with that controll .....not sure if has any effect on fuel effiency... :roll:

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Re: Using Resistors on the Sensors

Brian's picture

To Fish from Texas
I'm new to the forum and unable to find the original info regarding your resistor dilemma. The simple answer to your question is the coolant temp sensor is a thermistor with an inverse temp coefficient. ie the higher the resistance the lower the temp and vice versa. My question to you is why are you playing around with the CTS?? The info from this sensor is quite critical to maintaining the proper air fuel ratio. Adding resistance to the circuit will fool the PCM into thinking the engine is colder and it will richen the mixture accordingly (just like a choke only more precise). Reducing the resistance and fooling the PCM into thinking you are hotter will lean the mixture and save some fuel. The problem is if you have an electric fan it is controlled by that same CTS (usually set to come on between 95 to 108 deg C) running the fan all the time wastes all that fuel you just saved(Some older Japanese and European cars have a separate switch in the rad to control the fan but most if not all newer ones rely on the CTS). The leaner mixture will result in a more complete and hotter fuel burn. Hotter combustion temps are harder on engine components and result in higher NOX emissions.
I would like to read the article/post that suggests changing this value, perhaps I could be more helpful.

Brian

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Re: Using Resistors on the Sensors

FUELMIZER's picture

HI i think he meant less reistance, possible including outher fuel trim censors.anyway the whole idea i think is to help lean out the fuel system as we all know* make the p c m think the engine is warmer therefor less fuel added... and switching the HHO device on increases over all fuel economy .......

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Re: Using Resistors on the Sensors

fury fan's picture

Brian wrote:

To Fish from Texas
I'm new to the forum and unable to find the original info regarding your resistor dilemma. The simple answer to your question is the coolant temp sensor is a thermistor with an inverse temp coefficient. ie the higher the resistance the lower the temp and vice versa. My question to you is why are you playing around with the CTS?? The info from this sensor is quite critical to maintaining the proper air fuel ratio. Adding resistance to the circuit will fool the PCM into thinking the engine is colder and it will richen the mixture accordingly (just like a choke only more precise). Reducing the resistance and fooling the PCM into thinking you are hotter will lean the mixture and save some fuel. The problem is if you have an electric fan it is controlled by that same CTS (usually set to come on between 95 to 108 deg C) running the fan all the time wastes all that fuel you just saved(Some older Japanese and European cars have a separate switch in the rad to control the fan but most if not all newer ones rely on the CTS). The leaner mixture will result in a more complete and hotter fuel burn. Hotter combustion temps are harder on engine components and result in higher NOX emissions.
I would like to read the article/post that suggests changing this value, perhaps I could be more helpful.

Brian

He's meaning to add a resistor to the circuit, not to add to the overall resistance level. I suspect this is the thread he's referring to.
http://www.mpgresearch.com/forum/viewtopic.php?f=52&t=2171

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Re: Using Resistors on the Sensors

FUELMIZER's picture

HI TO ALL i think is grear being able to share each outher ideas....i think we all got our friend problem solved* now i have am slightly confussed about the T P S cenor or control not too shure just how to lower its out put to the car p c m . oh this car is 05 buick 3.1 L i thought adding some resistance in parelle to the ground wire was the way.....i appreciate some one helping me with this.....any way thanks don.. since my last post i have figured a way to trick the T P S ....good luck to all

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Re: Using Resistors on the Sensors

yahshua-First's picture

quote="qsiguy"]He means put a switch on your resistor and bypass it until the cars warmed up. That will eliminate your cold start issue. Also, I wouldn't wait until you figure out all your sensors before using the HHO. It's possible to get decent results from the HHO with only an EFIE installed. To make sense of your sensors you really need to first establish what the sensor is doing and how it changes based on temperature. I would check the resistance with your ohmmeter when the motor is cold and then start it and let it warm up and watch the reading. Does the resistance increase or decrease? This will tell you which direction you need to go with your resistor.

I'm posting this & another of my posts from another forum, so that you fellas won't get the idea that you can just buy something or try someones idea & your there. Very few i have seen get the immediate results they hope for without alot of research,work, & experiments w/many failures and a few success's...

june2008
workbench evolution...Bought e-bay abs plastic hho,used about $2.00 worth of the parts & built one using 1/2 gal. olive jar from wal-mart. Glass is fragile but dissapates heat much better/faster than any of the plastics. Electode mountings in conductive metal cap were challenge,o-rings w/thick hard rubber backup washers worked good. used several different catalysts in distilled water, baking soda caused quick red discoloring in electrolyte color[electrode breakdown?],gas production good using 6 setting battery charger on bench & clamp on amp. meter [15-20a]. used 4 different catalyst solutions, and chose potassium hydroxide as permanent electolyte mix,good gas production hardly any solution discoloration. The glass jar fit into an old empty go-jo plastic container,so trimmed down sides put so foam in the bottom & mounted next to wind shield washer res. on wifes vibe. Elect. hookup = +bat----25afuse holder----30a led on/off switch on dash----30a amp guage next to switch----then to the load contact side of 30a relay under hood mounted by fusebox----to gen + elctrode. control side of relay volts from engine running source[always]. After first exciting test drive went from 30mpg to 27mpg ,ouch [wife frowning]. Unit ran hot 18-22a because of heat buildup. Installed 1 1/2" flex hose from vent slots in front grille air dam up into eng. comp. running length of hho unit ,capped end of hose ,cut out a 6"long ,3/4" wide slot parralel w/hho so cooler outside air is blown around unit. went from 20a avg. to 12-13a. will be able to add P.H. to solution and make more gas w/cooler gen. operating temp. Tryed some engine tuning , 4.7k resist. in paralel w/iat sensor to give ecu higher than actual intake air temp. reading, 4.1k resist. in par. w/ ect sensor to give ecu hotter than actual coolant temp. reading. You pro's aren't gonna like this... wrapped elect. tape around maf sensor to give lower than actual airflow reading to ecu, had to trim tape a few times before engine would stay running.{have maf/o2 controller ordered} during test run after tuning car ran good with hho on, mpg now 23 :cry:
Am hoping i can straighten this mess out w/ the maf-02 controller,{Vibe has no MAP] supposed to control any O-2 sensor & solve problems the with introduction of HHO gas which causes higher exhaust oxy. content, which causes O-2 sensor to tell pcm[computer} to richen the fuel mix...
For you newer toyota, pontiac vibe... or whatever newer car you may have that has an AFR sensor, rather than a O-2 sensor.... an efie will not work ! none of the e-bay goodies will work! this is where i am stuck at present and so far have found no way to control the afr sensor where i can lean gas & see gains from HHO gen.

AFR circuit modification... july 26,08
Used 2 ea. 15 turn 10k cermit pots this wknd. One to precisely control voltage input from the high signal wire of the afr to the pcm. one to control the voltage input from the low {shield} wire of the afr. built units on bench then used battery in car to set pots to exact readings i had recorded the previous day from the afr sensor with only the maf adjuster on. hooked up pots & unhooked AFR. started engine right up. ALL seemed well until volt check... which i did intending to make leaning changes, turning pots either way made no change at all in the output voltage, but changing the maf setting made changes in voltage at pots??? Absolutely no hard wired conection between the MAF & POTS ??? Found that check engine light was on again, no scangauge so don't know exact reason. have always read 2vdc +/-range 0n low end and 2.4 +/- range on high end ...nothing i have done has changed those voltages except changing the maf does make very minut changes.
rick

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Re: Using Resistors on the Sensors

FUELMIZER's picture

HI the EFIE gave me immediately results .some said after the first tank ful of gas some say it takes 30 days..i wouldnt discourage anyone clamming fast results...highly possible they really have did their home work more throughly than others...

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Re: Using Resistors on the Sensors

FUELMIZER's picture

HI ..just a tip ..after reading wheather to use paraelle or series resistance in the MAF censor & map censor some say in parelle thats ok i guess however i found on this car using a variable resistance in series on the 5 volt wire instead of the ground wire seems to work better.... :) .realise i mean no conflick with any ones ideas ok..and for this car 05 buick adding resistance in series seems to help the MAP censor see lower vaccume....so as of now i havent touched the M A F ..the fresh air intake... realsing again each car & truck are different ....oh yes my wife car 01 olds same engine its fuel perminters have huge difference.....see what i mean....and its censors located same spot.. #-o good luck to all

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Re: Using Resistors on the Sensors

LarryClapp's picture

qsiguy wrote:

Raysp30 wrote:
I'm hoping to get a little help with this......

We're going to need some info to help. What kind of car? Do you have any diagrams of the electrical system? Typically, lowing the resistance of a temp sensor will effectively tell the receiver (ECU in this case) that the temperature is warmer. Higher resistance colder, lower resistance hotter. If you add resistance in series with the sensors output wire the ECU will assume colder air. To send a warmer air signal to the ECU you will need to wire a resistor in parallel with the AIT sensor. There will typically be a wire in and a wire out of the sensor. The new resistance, or POT, will go from the input to the output leads. If you can get your hands on a service manual for your vehicle it should tell you the specs for the sensors for testing. If you can locate it just get a thermometer and put it in water on the oven with the thermometer and measure the resistance across it while watching the temp. This way you can figure out that at 100*F ambient your sensor is at 1K ohms (example only), then at 120*F it's at 600 ohms, etc. Then you can decide how much resistance to add or subtract.

Here's a cool parallel resistance calculator. Enter the two values and it will show you what your output will be. For example, if the AIT sensor is at 1k and your pot is at 2.5K the ECU will see 714.29 ohms. As you lower the resistance of the pot the output will also lower. If both the AIT and your POT are at 1K the output will be 500 ohms. The formula is (R1xR2) / (R1+R2) = R3...R3 being the output resistance.

http://www.1728.com/resistrs.htm

Someone should post this in the Links page! This would have come in handy months ago.

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Re: Using Resistors on the Sensors

FUELMIZER's picture

Notsure wrote:

Well, as far as the IAT goes, I got rid of that resistor all together. Instead, I took the plastic air box out and blocked the incoming cool air from the fender well so the engine could actually breath warmer air. Then I simply moved the IAT sensor a bit closer to the radiator. NOT TOO CLOSE... :mrgreen:
This works great for me cause not only am I telling the car its getting nice warm air but it is actually getting it.

(12-13 -08) HI to all here i just receintly did what this man did* however i blocked of half of the air entering the main fresh air intale out in front of the air inlet.....so far that simple trick seems to work & i did add some wind defelectors & that with every thing also is helping considerable..to me does sound resionable less wind resistance more fuel millage ecomodder.com

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Re: Using Resistors on the Sensors

MPG101EES's picture

Hey try matching your CTS and IAT resistance to be the same. If it is an AFR car, use anywhere between 12-18 ohm resister on the AFR signal wire (usually blue).

On the downstream o2 sensors, use a 1/2 ohm resisitance in the heater circuit, does not matter which wire for the heater, and put a .1uf capasitor in between the signal and ground. This should help cut back your fuel some.

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