Using a resistor to cure high TPS resistance?

Max777 · 03-26-2010, 03:46 PM

EDIT: Did the math wrong... a resistor ADDS 800 to the 7,000 ohm value, not subtracts it... doh.

-Max.

I've been mucking around with my car a little, and found out that my TPS maxes out at 7K ohms. I checked the curve with a manual volt meter, and its nice and smooth, the only problem being that it has high resistance during full throttle....

I was wondering about wiring in a 800ohm resistor to the curcuit and resetting the RPM to cure this problem? A new TPS is $220, so I would love it as a temp fix for this problem. This would put my tps at 6200 ohms at full throttle, which is alright. All I would need to do is adjust the tps if this works correctly.

-Is the resistance curve on a TPS sensor linear? Will wiring in the resistor somehow skew the curve?

moremazda · 03-26-2010, 09:50 PM

How where you thinking about wiring that resistor in? By my math you would need a 63kohm resistance in parallel with the tps to get 6.3kohm

Max777 · 03-29-2010, 02:06 AM

Hmm, I don't know what I was thinking when I posted this...I need LESS resistance up top, the resistor thing would only make it higher.

Is there any way to "magically" drop TPS resistance? Or has that technology not been invented yet?

djmtsu · 03-29-2010, 07:06 AM

Is it possible to wire in a 'clamp' similar to to what an FCD does?

Max777 · 03-29-2010, 12:54 PM

probably, but an FCD is already in the price range of a good used TPS. I think I will try a used TPS and see.

RotaryProphet · 03-30-2010, 08:02 AM

First, check your -voltage-. The ECU pumps +5vdc through the TPS, and reads the result. If the voltage is very high, check your TPS ground. If it's very low, check your TPS +5v wire.

Lastly, if you need to lower the resistance, take the two wires you're trying to lower resistance between and add a resistor between them. With two electrical paths to follow, resistance will drop. If you have 7k resistance and add a 7k resister bypassing the TPS, you'll get 3.5k. Google will reveal the math to calculate the exact resister to change the peak to where you want it.

03-26-2010, 03:46 PM	#1
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	Using a resistor to cure high TPS resistance? EDIT: Did the math wrong... a resistor ADDS 800 to the 7,000 ohm value, not subtracts it... doh. -Max. I've been mucking around with my car a little, and found out that my TPS maxes out at 7K ohms. I checked the curve with a manual volt meter, and its nice and smooth, the only problem being that it has high resistance during full throttle.... I was wondering about wiring in a 800ohm resistor to the curcuit and resetting the RPM to cure this problem? A new TPS is $220, so I would love it as a temp fix for this problem. This would put my tps at 6200 ohms at full throttle, which is alright. All I would need to do is adjust the tps if this works correctly. -Is the resistance curve on a TPS sensor linear? Will wiring in the resistor somehow skew the curve? __________________ Rotaries:They are NOT that complicated! Last edited by Max777; 03-29-2010 at 02:07 AM..

03-29-2010, 02:06 AM	#3
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	Hmm, I don't know what I was thinking when I posted this...I need LESS resistance up top, the resistor thing would only make it higher. Is there any way to "magically" drop TPS resistance? Or has that technology not been invented yet? __________________ Rotaries:They are NOT that complicated!

03-29-2010, 07:06 AM	#4
djmtsu My minds tellin' me no... Join Date: Feb 2008 Location: Murfreesboro, TN iTrader: (10) Posts: 4,043 Rep Power: 21	Is it possible to wire in a 'clamp' similar to to what an FCD does? __________________ 1976 Mazda Cosmo RX-5 1976 Mazda Cosmo RX-5 2003 Toyota Tundra TRD 2015 Toyota 4Runner SR5

03-29-2010, 12:54 PM	#5
Max777 Pirate Join Date: Mar 2008 Location: Central IL iTrader: (5) Posts: 1,323 Rep Power: 18	probably, but an FCD is already in the price range of a good used TPS. I think I will try a used TPS and see. __________________ Rotaries:They are NOT that complicated!

03-26-2010, 09:50 PM	#2
moremazda shookmotorsports.com Join Date: Apr 2008 Location: Rockford, IL iTrader: (1) Posts: 108 Rep Power: 17	How where you thinking about wiring that resistor in? By my math you would need a 63kohm resistance in parallel with the tps to get 6.3kohm

03-30-2010, 08:02 AM	#6
RotaryProphet Rotary Fanatic Join Date: Sep 2008 iTrader: (0) Posts: 147 Rep Power: 17	First, check your -voltage-. The ECU pumps +5vdc through the TPS, and reads the result. If the voltage is very high, check your TPS ground. If it's very low, check your TPS +5v wire. Lastly, if you need to lower the resistance, take the two wires you're trying to lower resistance between and add a resistor between them. With two electrical paths to follow, resistance will drop. If you have 7k resistance and add a 7k resister bypassing the TPS, you'll get 3.5k. Google will reveal the math to calculate the exact resister to change the peak to where you want it.