Mustang idle surge and base idle reset

1slo5.0 · May 12th, 2009, 08:59 PM

Idle issues are common on these cars, especially 5-speed cars. EGR Valves, Idle Air Bypass solenoids and Throttle Position Sensors are common causes. A bad connection with the 10 pin (salt and pepper shakers) black and white engine electrical connectors can also cause poor idle quality. To ensure a good connection on the 10 pin connectors a little modification can be done which is fairly easy and will cure some surging and hanging idle issues on 86-93 Mustangs and should be the first thing done when tackling any idle issues.

10 Pin Connector modification:

1. Take the 10 pin connectors apart (salt and pepper shakers).

2. use a pick like tool to spread the male terminals open more so they make better contact. In the center of each male terminal there is a small seam and seams down the sides of the terminal which allows you to spread them open.

3. Apply some dielectric grease to the terminals

4. Plug the connectors back in.

Throttle Position Sensor (TPS) adjustment:

Without the proper adjustment, the throttle position sensor (TPS) will give the computer false reading as to the exact throttle opening. A false reading will limit wide open throttle performance. A voltage reading must be taken using a digital volt/ohmmeter (DVOM) with the Key On/Engine Off and with the Key On/Engine Running.

The TPS is located directly on top of the throttle body and is adjusted by loosening the two phillips mounting screws and swiveling the sensor until the highest reading is found. It may be necessary to elongate the holes with a small drill bit or small file to achieve the desired reading. The spec range for Key On is from .88 to 1.0 volt; shoot for the .90 to .98 volt. Make sure voltage reaches/exceeds 2.71v at WOT.

Incorrect Throttle Position Sensor (TPS) voltage will result in reduced performance including a possible hanging/surging idle. The best way to take a TPS voltage reading is by using two safety pins through the wires coming from the sensor. The positive lead is attached to the green wire, while the negative goes to the black wire. Always ground the meter through the sensor's black wire. This gives a direct, and more
accurate ground into the computer.

Resetting the base idle:

Clear the computer's idle memory by disconnecting the battery for 20+ minutes.

-Disconnect the Idle Air Bypass solenoid
-Reconnect battery
-Start engine and set idle speed to desired RPM with idle screw on throttle body
-Turn off engine and reconnect the air bypass solenoid
-Set TPS voltage between 0.90 - 0.95 volts with a digital volt meter
-Start engine and let it idle for 2 minutes with no accessories on.
-Turn off engine for two minutes
-Start engine again and run for 2 minutes with every accessory turned on.
-Turn engine off again.

crazy old cuban · May 14th, 2009, 04:27 AM

thank you for this info.

treblruh · May 27th, 2009, 01:02 AM

I Should have looked at the 5.0 forum first lol, thanks helpful information fixed my v6 problem in a hurry

ddarkslayer · June 6th, 2009, 06:34 PM

where is the skrew on the throttle body

1slo5.0 · June 7th, 2009, 07:28 PM

Originally Posted by ddarkslayer

where is the skrew on the throttle body

On the bottom.

88-gt-t-top · June 25th, 2009, 11:15 PM

Nice write up, I don't remember the older/longer one having a tip on making the TPS mounts any longer(room to swivel sensor).

Sabremike21 · July 4th, 2009, 02:57 AM

Well that answered one of my questions so far... Thanks

v8muscle · August 1st, 2009, 08:44 PM

theres no issue with doing this with a modded car it wont delete the tune etc...

1slo5.0 · August 1st, 2009, 10:12 PM

Originally Posted by v8muscle

theres no issue with doing this with a modded car it wont delete the tune etc...

No.

Needinfo321 · October 6th, 2009, 11:44 AM

I had the same problem in my car it is due to the year of the stang. it ended up being the solenoid. I bought all the parts needed online ofr $300

Hydration · November 9th, 2009, 12:42 PM

I did this to my car, whoever had it before me had the timing at 22 degrees advanced, tps completely out, dirty IAC, and cleaned those salt and pepper shakers.. he sold it cheap because he thought there was massive issues.. it runs like a charm now.

90fastang · November 21st, 2009, 07:36 PM

wats the salt and pepper shakers??

WDfrmTN · November 23rd, 2009, 04:23 PM

The big black & white connectors from the EEC harness to the INJ/sensor harness.
Ford Fuel Injection » 10-pin Connector Fix

90fastang · December 27th, 2009, 01:20 AM

my car was good and then all of a suden it idled at 3000 and it wouldnt drop, wat would it be??

PacificMustang01 · January 8th, 2010, 01:20 PM

OH JEEZZ! I too should have looked at the 5.0 section too for my problem. These are all good tips for dealing with idle issues. I think it applies to ALL Mustangs with these components. Very nice how-to! Thanks!!

fastback lover · January 27th, 2010, 01:22 PM

I never thought about the salt and pepper shakers for my friends 88. I will let him know. I know its old but thank you very much for the info.

stickstome2 · January 28th, 2010, 02:29 PM

Thats great info.

Chrome_Rust · February 13th, 2010, 07:30 PM

I have a 2.3 in a 90 that is hunting for it's idle.... will this work for that too?

Rush23 · February 21st, 2010, 11:07 AM

Will this work on a 94? I tried to pass emissions yesterday and it would not hold low rpm long enough to pass. It kept surging into high rpms, although nothing I can see on the tach.

ddarkslayer · February 24th, 2010, 11:51 AM

I can't even start up my car with the IAC unplugged

May 12th, 2009, 08:59 PM	#1
1slo5.0 Zippee is my step sister. 1990 Mustang LX 9.36@143 mph Join Date: Jan 2006 Location: Fond du Lac, Wisconsin Posts: 10,356	Mustang idle surge and base idle reset Idle issues are common on these cars, especially 5-speed cars. EGR Valves, Idle Air Bypass solenoids and Throttle Position Sensors are common causes. A bad connection with the 10 pin (salt and pepper shakers) black and white engine electrical connectors can also cause poor idle quality. To ensure a good connection on the 10 pin connectors a little modification can be done which is fairly easy and will cure some surging and hanging idle issues on 86-93 Mustangs and should be the first thing done when tackling any idle issues. 10 Pin Connector modification: 1. Take the 10 pin connectors apart (salt and pepper shakers). 2. use a pick like tool to spread the male terminals open more so they make better contact. In the center of each male terminal there is a small seam and seams down the sides of the terminal which allows you to spread them open. 3. Apply some dielectric grease to the terminals 4. Plug the connectors back in. Throttle Position Sensor (TPS) adjustment: Without the proper adjustment, the throttle position sensor (TPS) will give the computer false reading as to the exact throttle opening. A false reading will limit wide open throttle performance. A voltage reading must be taken using a digital volt/ohmmeter (DVOM) with the Key On/Engine Off and with the Key On/Engine Running. The TPS is located directly on top of the throttle body and is adjusted by loosening the two phillips mounting screws and swiveling the sensor until the highest reading is found. It may be necessary to elongate the holes with a small drill bit or small file to achieve the desired reading. The spec range for Key On is from .88 to 1.0 volt; shoot for the .90 to .98 volt. Make sure voltage reaches/exceeds 2.71v at WOT. Incorrect Throttle Position Sensor (TPS) voltage will result in reduced performance including a possible hanging/surging idle. The best way to take a TPS voltage reading is by using two safety pins through the wires coming from the sensor. The positive lead is attached to the green wire, while the negative goes to the black wire. Always ground the meter through the sensor's black wire. This gives a direct, and more accurate ground into the computer. Resetting the base idle: Clear the computer's idle memory by disconnecting the battery for 20+ minutes. -Disconnect the Idle Air Bypass solenoid -Reconnect battery -Start engine and set idle speed to desired RPM with idle screw on throttle body -Turn off engine and reconnect the air bypass solenoid -Set TPS voltage between 0.90 - 0.95 volts with a digital volt meter -Start engine and let it idle for 2 minutes with no accessories on. -Turn off engine for two minutes -Start engine again and run for 2 minutes with every accessory turned on. -Turn engine off again. __________________ Thanks to: Trick Flow, Team Z Motorsports, Total Engine Airflow and Furo Racecraft My daily driver has 16 cylinders and 4400hp @ 1000 rpm....

May 14th, 2009, 04:27 AM	#2
crazy old cuban Newbie 1990 mustang gt Join Date: Apr 2009 Location: west palm beach,fl Posts: 40	idle resets thank you for this info.

October 6th, 2009, 11:44 AM	#10
Needinfo321 Look Ma! My First Post! Join Date: Oct 2009 Posts: 1	Solenoid Problem I had the same problem in my car it is due to the year of the stang. it ended up being the solenoid. I bought all the parts needed online ofr $300

November 23rd, 2009, 04:23 PM	#13
WDfrmTN Regular 1991 Mustang 5.0 Join Date: Nov 2009 Location: West Tennessee Posts: 127	The big black & white connectors from the EEC harness to the INJ/sensor harness. Ford Fuel Injection » 10-pin Connector Fix __________________ "Seek to understand before you seek to be understood." Unknown "Life's tough...it's even tougher when you're stupid" John Wayne

February 13th, 2010, 07:30 PM	#18
Chrome_Rust Newbie 1993 Mustang LX Notch as fast as i can push Join Date: Sep 2009 Location: Findlay, OH Posts: 43	I have a 2.3 in a 90 that is hunting for it's idle.... will this work for that too? __________________ 1993 Notch, 306, UDP's, E-cam, 1.7's, TrickFlow track heat, BBK LCA's, FMS 1 5/8" Shorty's 3.73's 1996 Cobra Wheels, 2001 GT Brakes, SN95 Dash swap (working A/C), B&M Pro Ripper, 2.5" Flow's Dumped.

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May 27th, 2009, 01:02 AM	#3
treblruh Regular New 99 SVT Cobra Vert! Dunno Join Date: Apr 2009 Location: Tulsa,Oklahoma Posts: 215	I Should have looked at the 5.0 forum first lol, thanks helpful information fixed my v6 problem in a hurry

June 6th, 2009, 06:34 PM	#4
ddarkslayer Enthusiast 1988 Mustang 5.0 LX 12.48@118.27 Join Date: May 2009 Location: Folsom, CA Posts: 752	where is the skrew on the throttle body

July 4th, 2009, 02:57 AM	#7
Sabremike21 Newbie 1988 Mustang GT Conv N/A Join Date: Jul 2009 Location: Alaska Posts: 15	Well that answered one of my questions so far... Thanks

August 1st, 2009, 08:44 PM	#8
v8muscle Regular 1990 gt Join Date: Jul 2009 Location: va Posts: 128	theres no issue with doing this with a modded car it wont delete the tune etc...

November 9th, 2009, 12:42 PM	#11
Hydration Newbie 1987 5.0 Mustang Join Date: Jul 2009 Location: Vancouver Island Posts: 31	I did this to my car, whoever had it before me had the timing at 22 degrees advanced, tps completely out, dirty IAC, and cleaned those salt and pepper shakers.. he sold it cheap because he thought there was massive issues.. it runs like a charm now.

November 21st, 2009, 07:36 PM	#12
90fastang Newbie 1990 mustang lx 13.04@105 Join Date: Nov 2009 Location: california Posts: 14	wats the salt and pepper shakers??

December 27th, 2009, 01:20 AM	#14
90fastang Newbie 1990 mustang lx 13.04@105 Join Date: Nov 2009 Location: california Posts: 14	my car was good and then all of a suden it idled at 3000 and it wouldnt drop, wat would it be??

January 8th, 2010, 01:20 PM	#15
PacificMustang01 Regular 2001 Mustang 3.8L Join Date: Dec 2008 Location: San Diego Posts: 151	OH JEEZZ! I too should have looked at the 5.0 section too for my problem. These are all good tips for dealing with idle issues. I think it applies to ALL Mustangs with these components. Very nice how-to! Thanks!!

January 27th, 2010, 01:22 PM	#16
fastback lover Regular 1988 Mustang LX N/A Join Date: Sep 2007 Location: Arizona Posts: 90	I never thought about the salt and pepper shakers for my friends 88. I will let him know. I know its old but thank you very much for the info.

January 28th, 2010, 02:29 PM	#17
stickstome2 Newbie Join Date: Jan 2010 Posts: 5	Thats great info.

February 21st, 2010, 11:07 AM	#19
Rush23 Newbie 1994 Mustang Cobra Join Date: Feb 2010 Location: Albuquerque Posts: 8	Will this work on a 94? I tried to pass emissions yesterday and it would not hold low rpm long enough to pass. It kept surging into high rpms, although nothing I can see on the tach.

February 24th, 2010, 11:51 AM	#20
ddarkslayer Enthusiast 1988 Mustang 5.0 LX 12.48@118.27 Join Date: May 2009 Location: Folsom, CA Posts: 752	I can't even start up my car with the IAC unplugged

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Mustang idle surge and base idle reset

Mustang idle surge and base idle reset

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