Author Topic: Adjusting TPS  (Read 4361 times)

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Offline thatguyisjames

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Adjusting TPS
« on: December 27, 2010, 12:19:35 pm »
after a couple hundred thousand miles a lot of things wear out on your old honda.

one of the things i've noticed that kills MPG and can cause idling issues is the Throttle Position Sensor after some research i figured it out, and ending up fixed mine.

to start with is testing the TPS sensor to see if its even bad or wrongly adjusted.
personall y i had a old DX wiring harness sitting around, i de pinned the tps plug from the firewall plug. so i then had a little pigtail to plug into the TPS


using this i just extended the TPS so i could have bare wires to test with the voltmeter, if you don't have this option another easy thing is to de pin your plug and plug the wires back in. you just need to get to the exposed wire ends to test it.

the colors are as follows

yellow/white (5v+)
red/blue (signal)
green/white (ground)



turn the car to run (do not start)
use a voltmeter from red/blue (pos) to green/white (neg)
should test out somewhere near 0.45
open the throttle all the way open.
should test near 4.0

if this is what your reading then your within range, carry on with your day, if it reads anything different, or if when turning the throttle it doesn't "sweep" voltage, if its erratic ... example (.4, .9, .5, 2.3, 1.5) then you need to replace or adjust the sensor.



mine read too high, which made it back fire and get 25 mpg :( boooo

most people go "oh its riveted on, you cant adjust it"
bs, its a snap off bolt, they drill it on, once the head snaps off, its flat.


you have two options.
A) cut a strait line into it with a dermal, and make it a flathead bolt.
B) use a pair of vice grips CAREFULLY and get it to spin.

both are easier with the TB off the car.

since im a surgeon with vice grips i had mine off in nearly 5 mins. i grabbed the washer with the grips and went nice and slow to not tear the washer or strip it.

at this point the bolts are out and the tps can move freely
go buy some allen head bolts to make the TPS adjustabl e.

since everythin g is off the car and im in the house in the heat, i figured to adjusted the TPS inside.
the only thing i could think of off my head that was 5volts is USB.

i am warning you there is a chance you can burn out your USB charger or computer, so do this next step at your own risk, or just put it back on the car

i used this setup to test/ adjust it.


once i had it at 0.45 i tighten the allen heads down and slapped it back on the car.

the whole process took me less then 2 hours. and my car is currently getting its normal 40-45 mpg again
of course at the time of doing this i replaced fuel filter, spark plugs, and cleaned the air filter. which is a cheep tune up

all in all, id say very good mod/maintenance step for all old hondas.
the voltage readings i got from HT if anyone has diff info (civic repair manual showing diff please correct me)

Offline rbwdriven

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Re: Adjusting TPS
« Reply #1 on: December 27, 2010, 12:43:58 pm »
Nice.

added to faq's
« Last Edit: December 27, 2010, 12:45:34 pm by rbwdriven »

Offline Thundercat

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Re: Adjusting TPS
« Reply #2 on: December 27, 2010, 08:23:46 pm »
good info here....g olf clap
~CREW LEGIT~JJ AUTOWERKS
~IMPORTALLIANCE.ORG~All IN FAB~BISIMOTO~

Offline EFSleeper

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Re: Adjusting TPS
« Reply #3 on: December 27, 2010, 09:29:11 pm »
wow that just saved me a lot of looking cause i have been wondering for 3 days now how the stock dpfi tps wires went since i'm building a vtec harness now i know so i can swap them around right  ;D

Offline thatguyisjames

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Re: Adjusting TPS
« Reply #4 on: December 28, 2010, 02:09:55 am »
yep most people cut and flip the outer wires for DPFI > MPFI, silly rabbits, de pinning is WAY easier... unless you have to extend wires... yet i still like to de pin, keeps the wires correct.

thanks for the support guys, i only post when i know something .

funny story, i replaced my tps with a second one i had sitting around... . it wont fall back to .45 every time,
every other let off it catches at .5 then sometimes it drops to .3 before it should. trying to drive though a parking lot is interesti ng when it starts doing that. it will randomly fall on its face cuz it will cut fuel off before it should.

since i already have the allen heads on, its as simple as take off IACV and replace the TPS.

funny thing alot of people don't know, when the throttle is closed and the TPS reads below its .45 (i think thats the correct voltage) it will actually cut power to the fuel injectors, until the RPMs / Vacuum (i'm not sure which it watches) falls into idling zone, then it feeds fuel based on a idling fuel map, and sends signals to the IACV to let just enough air into the plenum.

the wobbling idling is normally a issue somewhere in between the TPS, IACV, and vacuum leak. at least thats how i've learned it.

i really wish someone would contradic t my informati on, i dont feel like im 100% on all that.