mattdel

sounds like a bad idle air ctrl

2 kwik

the surge is your car hunting for idle as well..do you have a chip or something?..you need to get that tps set first...check to see if the blade on t/b is closing right..also enlongated the holes on the ole tps and try it

Twisted

There are two ways to lower the tps voltage to within range. One, turn the idle set screw outward until it falls into range. This shouldn't permanently effect the idle speed, since it is computer controlled. And two, enlarge/slot the tps mounting holes so that the tps unit can be rotated, and the correct setting obtained.

5.0stanger

I was having the same problem with a surging idle until I did this.

Base Idle Reset Procedure (By Joel5.0)

1. Clean TB with carb cleaner and nylon brush (toothbrush size). Engine off, fully open TB blade and spray/brush TB until all gunk and oil residue is cleaned.

2. Allow to dry, or close TB blade and start engine until it clears all carb cleaner fumes/liquid.

3. Let engine idle...if it doesn't, increase idle speed via TB stop screw until engine stays idling on its own.

4. Disconnect IAC valve, if engine dies repeat 3 with IAC disconnected.

5. Set idle speed to the lowest setting possible between 650-850 rpms with IAC disconnected. It is key to use the lowest possible to prevent idle surge, rolling, etc once the IAC is connected as follows.

6. Turn engine off, and reconnect IAC

7. With Ign On Eng Off, check TPS voltage output....if it's between .8vdc - 1.0vdc, it's OK. This voltage check should be done between the Green and Black wires at the TPS side connector as shown in the pic below (FYI: Green = TPS Signal, Black = SIGRTN, and Orange = VREF)....(-) terminal of the DVOM on the Black wire and (+) terminal on the Green wire.



8. Disconnect battery (-) for 3-4 minutes.

9. Reconnect battery, start engine, allow it to idle for 2-4 minutes to confirm setup,

10. If idle speed falls too low or stalls, increase idle speed via the TB set screw a little at a time.

11. Turn engine off for 20 seconds, re-start engine and repeat 9 - 11 if required.

12. Reconfirm TPS output is within the .8vdc - 1.0vdc range optimum range.

NOTES:

1. No need to reset ECM KAM (reset computer), the TPS minimum value used for idle control, is reset automatically by the EEC-IV every time the ign is cycled on-off for 20 seconds-on.

2. If the TPS output is within 6vdc - 1.1vdc, it's still acceptable, since no TPS failure codes will be generated, and it falls within the EEC-IV .5vdc - 1.19vdc working range.

13. Allow a 10-20 minute "relearning" period under normal driving conditions (drive cycle).....you're done!

5.0stanger

https://mustangforums.com/m_969165/tm.htm <-look there for some more tips on setting TPS

Jared_blown5.0

thanks but i already did that stuff a few times, also no vacum leaks.

5.0stanger

Well, you didn't do it right if you can't get your TPS voltage down below 1.0. What I like to do is get it so my car just barley stalls when I unplug my IAC by adjusting the TB idle screw, then I set my TPS to .98. I had to oblong my TPS to get it right. It used to hang about 1500 to 1800 RPMs when my base was set too high, and it will surg if your TPS is out of adjustment. Mine is perfect now doing it this way. You check your TPS voltage while you car is off and ignition is on BTW. Good Luck

9tyfiveo

THANK YOU. took FOREVER to make sure the idle had to be just before it stalls.

dudeboy

DANGER!
bad tech....

take a gander at this...
https://mustangforums.com/m_4613249/tm.htm


jason