Engine Idle issue - Possible Vac leak - canister purge valve?

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R82148V

Active Member
May 26, 2020
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UPDATE!!

After double checking every possible Vacuum source / component, I was able to narrow it down to the purge valve being stuck open allowing a constant vac leak during idle. I replaced with a new motorcraft valve and that did the trick stopping the constant vac at idle. I also inspected and opened all the 10 pin pins for better contact. I thought now the idle should calm down and stop the surging but it didn't. Idle was still at about 950 and still surge slooowly up to 1300 when hitting the throttle. If you hit it again, it would calm back down to 950 rpm..
I checked the vacuum level at idle. It's a steady 20 and 22 if I hold the rpms at 1500.

I wanted to perform another base idle reset. This time pulling the spout as you guys suggested. Timing was and is right at 10 btdc.
Well I'm excited to say that pulling the spout did the trick!! :rock:Before doing an idle reset with the spout in, I could never the base idle down to 600 rpm using the throttle plate screw / IAC pulled. the lowest I could get it was 750.. Now with pulling the Spout?!! I actually had to turn UP the screw to keep it running.. haha and I was now able to dial it in to 600 / 625! After doing the entire reset with your suggestion, I now have her idling at 750 range and no surge! :cheers:

I know there's a ton of write ups about how to perform a base idle reset, but I every list I found, there's always something different and a lot of them don't say to pull the spout. I would like the opportunity to present my own BASE IDLE RESET PROCEDURE that I pieced together from you tube, forums, posts and ford bulletins. I'm sure everyone has their own way of doing an idle reset but I found this procedure to work for me, curing my high idle and slight surge hanging idle. Just make sure your timing is correct (Factory spec is 10° btdc) and you do not not not have any vac leaks before performing an idle reset for the best possible outcome.


WRENCH 23's BASE IDLE RESET PROCEDURE
1. Warm Engine to temp then turn off
2. Disconnect Battery for 10 minutes
3. Disconnect IAC connection, TPS connection and pull the SPOUT

This will remove all ECU connections controlling idle.
4. Reconnect the battery and start engine.
5. Manually set idle between 600 - 650 rpms (600-625 preferred) using the throttle plate screw located under the Throttle Body.

If idle is too low and doesn't stay running, turn the idle screw clockwise a quarter turn and try again.
6. Once base rpms are achieved, turn off engine and reconnect IAC, TPS and SPOUT.
7. With KOEO (key on engine off) set the TPS voltage between .90-.95 volts.

You achieve this by probing the green wire as positive and the black wire as negative. for the most accurate reading, use the black wire ONLY as ground!
Loosen the TPS slightly and now test between the green and black wire using a digital multimeter.
Turn the TPS until you're dialed in between .90-.95 volts.
You may need to remove the TPS and elongate the holes slightly to get enough movement to dial in.
8. Start engine and idle for 2 minutes without any accessories on. Time it!
9. Turn off engine for 2 minutes. Time it!
10. Start engine again and idle for another 2 minutes but this round with all accessories on. Time it!

(headlights, hazards, Hvac blower) anything to draw current and create a load.
11. Turn off engine.

You have completed your base idle reset procedure!

You should notice your idle is now dialed in around 750 rpm.

Thanks again everyone. I hope this helps someone!
:coff:
 
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mattys91gt

Active Member
Feb 3, 2022
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Plymouth Massachusetts
you didn't learn nothin from me, I just regurgitate stuff others have posted to help members with problems and maybe a little googlefu thrown in just to make me sound like I know what I'm posting.
could u help me with a vacuum leak also I took out my smog system and this is my first mustang I took the tad and tab vacuum lines off and to the EGR I hooked up one silonoid with the green and red and tried to run them to the back of intake and EGR I've looked at the diagram and I'm confused on where to plug stuff
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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polk county florida
could u help me with a vacuum leak also I took out my smog system and this is my first mustang I took the tad and tab vacuum lines off and to the EGR I hooked up one silonoid with the green and red and tried to run them to the back of intake and EGR I've looked at the diagram and I'm confused on where to plug stuff
Do you have a thread started with this problem?