Throttle Position Sensor? - Subaru Impreza GC8 & RS Forum & Community: RS25.com

RichAwesome · 06-30-2009, 06:54 PM

I'm driving a '99 RS 2.5 Just replaced my MAF and IACV. Now it seems my TPS is on the fritz. Trying to adjust it only results in far too high idle rpm (6500) or too low in which my intake sucks in air like a vacuum. Does it sound like its shot? Should I just throw a new one on there? Is there a proper way to adjust it that I don't know about? Should I try setting it then resetting my ECU?

**tnice17** · 06-30-2009, 07:34 PM

well mine has even space on both sides of adjustment, but every car is different.

depending on how deep into diagnosing it you can do these tests.

the TPS gets 5v, yes 5, not 12.

hard - you can get a multimeter and the wirediagram and back prob the wires on the TPS ( be careful of the weather seal on the wires. poke the correct wire and then open/close the throttle and watch the voltage move.

easy - ( but may not be so accurate) start the car, loosen the screws and move the TPS back and worth, then set it to get the desired idle. keep in mind that it may not work because of the ECU relearning and all that stuff.

yes try resetting the ECU first.

n2x4 · 06-30-2009, 08:35 PM

Are you sure there isn't a vacuum leak somewhere?

Typically the TPS shoudn't be adjusted, and I'm pretty confident that no amount of adjusting could cause the sensor to have you idle at redline.
Were you getting check engine lights for these issues? What started all of this?

RichAwesome · 07-01-2009, 05:55 PM

Well I was getting a Check engine coded for higher then expected idle. I figured it was my IACV because when I checked it it was all carboned up and getting stuck wide open. I replaced that but it didn't fix my problem, that being the idle jumping up and down when the IACV was plugged in. I decided to check all of my sensors just to see if they were gunked up or anything and once I hooked the TPS back up, thats when the rev issue came in.

R-raid · 07-01-2009, 07:54 PM

Quote:

Originally Posted by RichAwesome

I'm driving a '99 RS 2.5 Just replaced my MAF and IACV. Now it seems my TPS is on the fritz. Trying to adjust it only results in far too high idle rpm (6500) or too low in which my intake sucks in air like a vacuum. Does it sound like its shot? Should I just throw a new one on there? Is there a proper way to adjust it that I don't know about? Should I try setting it then resetting my ECU?

When I messed around with my tps and reset the ecu it did nothing. cel came on right away and the car was running the same. Get a professional to do it because I made mine sooooooo much worse trying to fix it.

RichAwesome · 07-03-2009, 04:04 PM

Hahaha I was trying to avoid the financial burden of a professional.

OGspartan · 02-27-2010, 01:32 PM

Didn't want to start a new thread so I just figured I'd ask my question right here...I'm in the middle of adjusting my TPS. I'm doing what the manual says and probing the right terminals with the ignition on but all i keep getting even when I move the throttle is .02 volts...Does that mean my TPS is fucked? Any input is appreciated.

zze86 · 02-28-2010, 06:50 AM

^ If the throttle is stationary and that's all you're getting then you should be OK, if it's within specs.

If you're moving the throttle or tps around and that's all you're getting then you'll need a new one.

OGspartan · 03-02-2010, 02:33 PM

So...turns out that some connectors that were supposed to be connected...weren't connected, which is why I kept getting .02. In the manual it says the range at closed throttle is .45 V - .55 V. But all i get while moving the TPS around ranges from 4.30 V - 4.98 V. I recall someone said something about the sensor getting 5 V. So am I just supposed to subtract what it should be .5 V from 5 V to get 4.5 V. Just hoping someone can chime in to make sure its supposed to be that way. TPS is good cause the voltage lowers as i open the butterfly.

**tnice17** · 03-02-2010, 02:46 PM

Quote:

Originally Posted by tnice17

well mine has even space on both sides of adjustment, but every car is different.

depending on how deep into diagnosing it you can do these tests.

the TPS gets 5v, yes 5, not 12.

hard - you can get a multimeter and the wirediagram and back prob the wires on the TPS ( be careful of the weather seal on the wires. poke the correct wire and then open/close the throttle and watch the voltage move.

easy - ( but may not be so accurate) start the car, loosen the screws and move the TPS back and worth, then set it to get the desired idle. keep in mind that it may not work because of the ECU relearning and all that stuff.

yes try resetting the ECU first.

Quote:

Originally Posted by OGspartan

So...turns out that some connectors that were supposed to be connected...weren't connected, which is why I kept getting .02. In the manual it says the range at closed throttle is .45 V - .55 V. But all i get while moving the TPS around ranges from 4.30 V - 4.98 V. I recall someone said something about the sensor getting 5 V. So am I just supposed to subtract what it should be .5 V from 5 V to get 4.5 V. Just hoping someone can chime in to make sure its supposed to be that way. TPS is good cause the voltage lowers as i open the butterfly.

yes your info seems to be correct.

the ECU will never see 100% of the 5v. if it does, there is a problem. it shouldnt see 0v either. if it does, there is a fault in the circuit

the TPS is a potentiometer FIY

06-30-2009, 06:54 PM	#1 (permalink)
RichAwesome 1.8L My: Subaru Parts for sale Join Date: Apr 2009 Trader Rating: (0) Posts: 21	Throttle Position Sensor? I'm driving a '99 RS 2.5 Just replaced my MAF and IACV. Now it seems my TPS is on the fritz. Trying to adjust it only results in far too high idle rpm (6500) or too low in which my intake sucks in air like a vacuum. Does it sound like its shot? Should I just throw a new one on there? Is there a proper way to adjust it that I don't know about? Should I try setting it then resetting my ECU?

06-30-2009, 07:34 PM	#2 (permalink)
tnice17 Premium Member Car: RS>RSL (in progress) Fav Mod: resurrection abilities My: Subaru Parts for sale Join Date: Aug 2007 Location: danbury, CT Trader Rating: (21) Posts: 3,999	well mine has even space on both sides of adjustment, but every car is different. depending on how deep into diagnosing it you can do these tests. the TPS gets 5v, yes 5, not 12. hard - you can get a multimeter and the wirediagram and back prob the wires on the TPS ( be careful of the weather seal on the wires. poke the correct wire and then open/close the throttle and watch the voltage move. easy - ( but may not be so accurate) start the car, loosen the screws and move the TPS back and worth, then set it to get the desired idle. keep in mind that it may not work because of the ECU relearning and all that stuff. yes try resetting the ECU first. __________________ Single Cylinder Mafia

02-27-2010, 01:32 PM	#7 (permalink)
OGspartan 2.7L Car: 93 Eggshell Blue Impreza Fav Mod: EJ25 My: Subaru Parts for sale Join Date: Sep 2005 Location: Los Angeles Trader Rating: (3) Posts: 347	Didn't want to start a new thread so I just figured I'd ask my question right here...I'm in the middle of adjusting my TPS. I'm doing what the manual says and probing the right terminals with the ignition on but all i keep getting even when I move the throttle is .02 volts...Does that mean my TPS is fucked? Any input is appreciated. __________________ Something witty

02-28-2010, 06:50 AM	#8 (permalink)
zze86 2.5L Car: 1996 Impreza L Wagon Fav Mod: 3/8 Ratchet & Socket Set My: Subaru Parts for sale Join Date: Nov 2008 Location: Madison, WI Trader Rating: (6) Posts: 226	^ If the throttle is stationary and that's all you're getting then you should be OK, if it's within specs. If you're moving the throttle or tps around and that's all you're getting then you'll need a new one. __________________ My GF8 build Journal

03-02-2010, 02:33 PM	#9 (permalink)
OGspartan 2.7L Car: 93 Eggshell Blue Impreza Fav Mod: EJ25 My: Subaru Parts for sale Join Date: Sep 2005 Location: Los Angeles Trader Rating: (3) Posts: 347	So...turns out that some connectors that were supposed to be connected...weren't connected, which is why I kept getting .02. In the manual it says the range at closed throttle is .45 V - .55 V. But all i get while moving the TPS around ranges from 4.30 V - 4.98 V. I recall someone said something about the sensor getting 5 V. So am I just supposed to subtract what it should be .5 V from 5 V to get 4.5 V. Just hoping someone can chime in to make sure its supposed to be that way. TPS is good cause the voltage lowers as i open the butterfly. __________________ Something witty

06-30-2009, 08:35 PM	#3 (permalink)
n2x4 2.0L Turbo Car: 95GF4 , 99SF5 Fav Mod: More Boost! My: Subaru Parts for sale Join Date: Jul 2007 Location: Carrollton, Ohio Trader Rating: (5) Posts: 1,191	Are you sure there isn't a vacuum leak somewhere? Typically the TPS shoudn't be adjusted, and I'm pretty confident that no amount of adjusting could cause the sensor to have you idle at redline. Were you getting check engine lights for these issues? What started all of this?

07-01-2009, 05:55 PM	#4 (permalink)
RichAwesome 1.8L My: Subaru Parts for sale Join Date: Apr 2009 Trader Rating: (0) Posts: 21	Well I was getting a Check engine coded for higher then expected idle. I figured it was my IACV because when I checked it it was all carboned up and getting stuck wide open. I replaced that but it didn't fix my problem, that being the idle jumping up and down when the IACV was plugged in. I decided to check all of my sensors just to see if they were gunked up or anything and once I hooked the TPS back up, thats when the rev issue came in.

07-03-2009, 04:04 PM	#6 (permalink)
RichAwesome 1.8L My: Subaru Parts for sale Join Date: Apr 2009 Trader Rating: (0) Posts: 21	Hahaha I was trying to avoid the financial burden of a professional.

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