Please don't throw stones at me

Rodoggx · 10-24-2002, 06:21 PM

Hey guys,
I know this is probably a stupid question...but, does anyone know how to check and change the voltage on a 5.0's Throttle position sensor? My idle is still a bit rough and this is next on my list of things to do. Thanks

NotchJohnson · 10-24-2002, 07:24 PM

You have to find the hot and ground wires coming out of the sensor and check the voltage. A digital one works best in my opinion. There are two screws holding the sensor in place, there is one that you can loosen a little bit, and the sensor will rotate. Only loosen this screw a little bit and move it slightly. Check your voltage as you adjust it, and set it to .98 volts. Sometimes its a pain to keep it there, mine liked to jump a little as I was tightening it. Good luck - John

Rodoggx · 10-24-2002, 08:25 PM

If I adjust it correctly, my idle might improve right?

NotchJohnson · 10-24-2002, 08:29 PM

It depends, there are lots of things that can screw up an idle. It might be your prob, and it might not. Before you mess with the sensor, check the voltage, you dont want to mess with it if its not the problem.

jimberg · 10-24-2002, 10:22 PM

The only way the TPS could really affect your idle is if it is reading above 1v. This would fool the computer into thinking you are at part throttle. You only need to make sure that voltage is at around .85v to .95v. The idea of getting it as close to 1v as you can to improve throttle response is just a myth that we really have to kill.

Use a digital meter as suggested. Neg probe goes to black wire and positive probe goes to green wire. Turn the ignition to the on position to check it. There is no need to start the car. Move the throttle lever slowly and make sure there are no skips in the voltage. If there are, replace the TPS. It should go from just below 1v to about 4.5 v. Release it slowly and make sure voltage is still below 1v. If it is above 1v, loosen the screw and wiggle it around until you get it solidly under 1v and then tighten the screws.

That's about it.

Rodoggx · 10-24-2002, 11:42 PM

You guys have been very helpful, thank you.

RED92LX50 · 10-25-2002, 07:39 AM

You may want to try and "Reset" your computer. There is a detailed article on the corral-dot-net (replace -dot- with a .) website on the procedure. It seems to clear up idle problems for many people.

jim_howard_pdx · 10-25-2002, 11:16 AM

I like to reset the computer after every change I make to the engine. I think this is VERY good advice. The EPROM chip set remembers the previous settings until it is cleared of memory. I used to do this with my friends cars without explaining what I did and they were just amazed at the difference and how well the car ran.

Remember too that spark plugs and plug wire quality have alot to do with idle quality. If the electrodes are worn, or the wire is cooked then you will run poorly no matter what.

Also, If you are running an MSD or Crane Hi6 like I am, YOU MUST RUN SPIRAL CORE WIRES. The graphite type resistance wire will not take the multiple sparks for long before TOASTING.

moc · 10-26-2002, 12:05 AM

You may have a very dirty IAC (Idle Air Control) it's the cylindrical looking thing ,attached to your throttle body ,with the electrical lead coming off the bottom of it . You need to remove it (2 bolts ,and disconnect the lead ) do youself a favour and disconnect the battery ( for at least 30 mins ,while you are cleaning the IAC ) soke it some carb cleaner ,(after you have removed ,the solenoid part of it (by removing the 2 phillips head screws) soke it , assemble it ( be careful with the removal of the gasket ) most times you can reuse it over ,over again . then after you connect the lead , connect the battery . this should calm your idle woes

10-24-2002, 06:21 PM	#1
Rodoggx Registered Member Join Date: Oct 2002 Location: VA. Posts: 71	Please don't throw stones at me Hey guys, I know this is probably a stupid question...but, does anyone know how to check and change the voltage on a 5.0's Throttle position sensor? My idle is still a bit rough and this is next on my list of things to do. Thanks __________________ 1990 Mustang LX 5.0 - All STOCK!!!! Wha?!!! Stock???.... no money for mods..

10-24-2002, 07:24 PM	#2
NotchJohnson Registered Member Join Date: Oct 2001 Location: Florida Keys Posts: 593	You have to find the hot and ground wires coming out of the sensor and check the voltage. A digital one works best in my opinion. There are two screws holding the sensor in place, there is one that you can loosen a little bit, and the sensor will rotate. Only loosen this screw a little bit and move it slightly. Check your voltage as you adjust it, and set it to .98 volts. Sometimes its a pain to keep it there, mine liked to jump a little as I was tightening it. Good luck - John __________________ 89 notch-finally not stock!! ported gt40's, ported cobra intake, 65mm tb, 75mm maf, mac cai, lt's,prochamber, fms 1.6 rr, 125 shot.

10-24-2002, 08:25 PM	#3
Rodoggx Registered Member Join Date: Oct 2002 Location: VA. Posts: 71	If I adjust it correctly, my idle might improve right? __________________ 1990 Mustang LX 5.0 - All STOCK!!!! Wha?!!! Stock???.... no money for mods..

10-24-2002, 08:29 PM	#4
NotchJohnson Registered Member Join Date: Oct 2001 Location: Florida Keys Posts: 593	It depends, there are lots of things that can screw up an idle. It might be your prob, and it might not. Before you mess with the sensor, check the voltage, you dont want to mess with it if its not the problem. __________________ 89 notch-finally not stock!! ported gt40's, ported cobra intake, 65mm tb, 75mm maf, mac cai, lt's,prochamber, fms 1.6 rr, 125 shot.

10-24-2002, 10:22 PM	#5
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	The only way the TPS could really affect your idle is if it is reading above 1v. This would fool the computer into thinking you are at part throttle. You only need to make sure that voltage is at around .85v to .95v. The idea of getting it as close to 1v as you can to improve throttle response is just a myth that we really have to kill. Use a digital meter as suggested. Neg probe goes to black wire and positive probe goes to green wire. Turn the ignition to the on position to check it. There is no need to start the car. Move the throttle lever slowly and make sure there are no skips in the voltage. If there are, replace the TPS. It should go from just below 1v to about 4.5 v. Release it slowly and make sure voltage is still below 1v. If it is above 1v, loosen the screw and wiggle it around until you get it solidly under 1v and then tighten the screws. That's about it. __________________ 351W 89 Mustang GT Convertible

10-24-2002, 11:42 PM	#6
Rodoggx Registered Member Join Date: Oct 2002 Location: VA. Posts: 71	You guys have been very helpful, thank you. __________________ 1990 Mustang LX 5.0 - All STOCK!!!! Wha?!!! Stock???.... no money for mods..

10-25-2002, 07:39 AM	#7
RED92LX50 Registered Member Join Date: Aug 1999 Location: Fairfax, VA Posts: 220	You may want to try and "Reset" your computer. There is a detailed article on the corral-dot-net (replace -dot- with a .) website on the procedure. It seems to clear up idle problems for many people. __________________ 1992 LX 5.0 Convertible Red/Blk Gears, Exhaust, bolt-ons... R.H.C. #51

10-25-2002, 11:16 AM	#8
jim_howard_pdx Registered Member Join Date: Apr 2002 Location: Portland Oregon Posts: 247	I like to reset the computer after every change I make to the engine. I think this is VERY good advice. The EPROM chip set remembers the previous settings until it is cleared of memory. I used to do this with my friends cars without explaining what I did and they were just amazed at the difference and how well the car ran. Remember too that spark plugs and plug wire quality have alot to do with idle quality. If the electrodes are worn, or the wire is cooked then you will run poorly no matter what. Also, If you are running an MSD or Crane Hi6 like I am, YOU MUST RUN SPIRAL CORE WIRES. The graphite type resistance wire will not take the multiple sparks for long before TOASTING. __________________ 1966 Customized for daily street and highway domination. 358 Windsor running 425 HP C-4 Auto and 3.25 Posi

10-26-2002, 12:05 AM	#9
moc Registered Member Join Date: Mar 1999 Location: Ocean City , Maryland Posts: 344	Sounds like You may have a very dirty IAC (Idle Air Control) it's the cylindrical looking thing ,attached to your throttle body ,with the electrical lead coming off the bottom of it . You need to remove it (2 bolts ,and disconnect the lead ) do youself a favour and disconnect the battery ( for at least 30 mins ,while you are cleaning the IAC ) soke it some carb cleaner ,(after you have removed ,the solenoid part of it (by removing the 2 phillips head screws) soke it , assemble it ( be careful with the removal of the gasket ) most times you can reuse it over ,over again . then after you connect the lead , connect the battery . this should calm your idle woes __________________ 1991 5.0 NotchBack,Black as of 05/04/09 34,300mi. 2001 LIGHTNING Black 29,872 mi. 05/04/09 (Hangar Queen) SMOKEM UP

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