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Resistor for Map sensor
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pdai11 Offline
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Resistor for Map sensor
I would like to make a simple map enhancer with a Pot and a resistor for my 96 Toyota Rav4. I have seen many people using different resistor ohms. A diagram from Mike's tuning for mileage stating 50k pot and 100k resistor and water4gas uses a 33k resistor and others has different ohms, very confusing, any members has made one that actually working on a Toyota ?
04-29-2010 04:50 AM
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jbalat Offline
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RE: Resistor for Map sensor
You need to find out if it is frequency based or voltage based. Do you have a service manual so you can figure out which wire to look at ?
If frequency then mike has a product in the store....
04-30-2010 01:37 AM
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pdai11 Offline
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RE: Resistor for Map sensor
Hi, it's voltage based, any idea ?
05-01-2010 03:49 PM
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thomasbala Offline
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RE: Resistor for Map sensor
(05-01-2010 03:49 PM)pdai11 Wrote:  Hi, it's voltage based, any idea ?
If it's voltage based why don't you use a 100k variable resistor (potentiometer) and experiment with various settings. Start with a resistance just below stall and decrease from there. Keep in mind that you can use more resistance at 60 mph than at 20 mph. Thus, I don't think you'll find one setting that fits all driving conditions. Once you find your best setting at say 60 mph measure it with a multimeter; then find your best setting in stop & go city traffic; measure it. Now you can rig a MAF sensor with 2 resistors; one for city driving and one for interstate speeds and switch between them. An EFIE beats a MAF sensor every time. Reason being that the O2 sensors or AFR's have the last word as far as how much fuel is going to be injected. Good luck.
05-01-2010 05:25 PM
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justing Offline
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RE: Resistor for Map sensor
When tuning you have to consider all sensors. AFR and O2 are very important. your mas air flow and map sensors give the ECU information about load the engine is under. Air intake and coolant temp sensors adjust timing and lower your lean limits. They all must work together to keep the ECU happy. From what I have read, tuning OBDII is a task best done with a diagnostic computer.

Justin Green
Chattanooga TN
2004 Kia Optima
from 22MPG to 26.5MPG
VOLO FS-2
05-01-2010 06:45 PM
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thomasbala Offline
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RE: Resistor for Map sensor
(05-01-2010 06:45 PM)justing Wrote:  When tuning you have to consider all sensors. AFR and O2 are very important. your mas air flow and map sensors give the ECU information about load the engine is under. Air intake and coolant temp sensors adjust timing and lower your lean limits. They all must work together to keep the ECU happy. From what I have read, tuning OBDII is a task best done with a diagnostic computer.
If you want bang for the buck you will get much more of an mpg increase from an EFIE than a MAF or MAP sensor modification, and very little increase from an AIT or ECT modification. As far as tuning OBDII, there is nothing to tune in the sense of timing adjustment, dwell angle, idle mixture, etc. like there used to be before computers controlled ICE's. You'd be lucky to find an idle speed adhustment screw nowadays. The only way you're going to "tune" for mileage is to modify the sensors, the O2 or AFR's being the major ones. At the very last instant before the ECU sends a pulse width signal to the injectors it takes a reading from the O2 sensors or AFR's, overrides the MAF, AIT, ECT, MAP sensors and sends the signal. Software that will give you a ton of readings on your ECU signals really isn't very helpful. Those that have tuned for mileage know that you make a change, drive a set course, measure mpg and adjust. Just play with an analog EFIE to see what I mean.
05-02-2010 09:15 AM
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