Help me create the "Surging Idle Checklist"

Discussion in 'Fox 5.0 Mustang Tech' started by jrichker, Apr 10, 2005.


  1. leathernotch

    leathernotch New Member

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    Unhooked IAC and the car revs and comes down in the Rs just fine but now idles at 1100.

    So bad Iac????????????/
  2. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    There is an O ring that seals the injector to manifold gap. If those O rings drop down into the manifold because the pintile cap that holds them in place is missing, you will get a vacuum leak.

    Diagram courtesy of Tmoss & Stang&2birds
    Notice the brown cap on the end of the 19# injector. That is the pintle cap that retains the O ring that is the injector body to manifold seal.
    [​IMG]
    See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/


    Go through the checklist on the first post, there are a number of checks to go through. There is a proceedure to test & set the base mechanical idle. If you cannot set the base mechanical idle on a warm engine, you definitely have a vacuum leak.
  3. leathernotch

    leathernotch New Member

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    I am thinking multi problem could the iac be what is keeping the idle at 2k or higher when reved before comeing down, cause it isn't sticking when the iac is unpluged. So I am think O rings and the IAC I just bought and did the rebuild kit for the injectors on a friends car so I know where to get them just trying to figure out if it is causeing everything or maybe just the raised idle and not the sticking up high
    '
  4. TENGRAM

    TENGRAM New Member

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    the hanging rpm you are experiencing is called "dashpot". its supposed to do that a little bit. once your idle is lowered to the appropriate rpm it will not be an issue. focus on the vacuum leak possibility and getting your idle right. my2cents
  5. Skoobie

    Skoobie Damn...Tyler65's hot!

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    This isn't in responce to a particular post but I thought I would throw it in for users of the IAC adjustment plate. I've had a vac leak for a LONG time that i could not track down. When I got the car the previous owner had installed the adjuster plate. When I had a vac line fail (before I knew what was going on) I tried to compensate for the loss of idle control with the plate by opening the screw more. Well eventually I discovered the bad vac line and replaced it but I forgot about the plate I had adjusted. Well for months I delt with a crappy idle and MAJOR hesitation in the lower rpms. I was about to burn the whole car when my buddy made a comment about how loud my intake was. I had gotten so use to the noise I hadent thought about it until he started his car (same CAI) and he had next to no noise...so I worked my way up the intake path until I got to the plate. I started to tighten the adjustment screw and low and behold the noise went away and my idle started to stabilize....I was extatic and ****ed all at once :nonono: The plate had been opened so far it was creating a huge vacuum leak. Kind of like White Pony's problem with his throttle blade. So if you own one of those plates make sure you have it set right or they will do far more harm then good.
  6. leathernotch

    leathernotch New Member

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    Check the TPS over and it was at 1.11 so I dialed it down to .90 then reset the battery. Now I have started her a few times and she is idleing at 1k and the vac is reading 13
    Is that really low??
    I have the B cam w/ 1.7s
  7. leathernotch

    leathernotch New Member

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    I have the adj for the tps but what does the one for the iac look like?????
  8. leathernotch

    leathernotch New Member

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    :) Replaced the IAC and she warmed up and Idled at 700, :( but the vac is reading 10. So........ vac leak wasn't idle issue?????
  9. Skoobie

    Skoobie Damn...Tyler65's hot!

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    Thats about a normal hg for that cam. I run an E cam and have 12-13hg
  10. webslinger67

    webslinger67 New Member

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    i think i might have been incorrect, but, i want to clear the codes from my EECM , how do i do that? I have already read them, now i just wanna clear them..
  11. JimBowy

    JimBowy Member

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    disconnect the battery, tap the brake a few times, then let the car sit for 10 minutes
  12. webslinger67

    webslinger67 New Member

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    i just found out the procedure to do it with the meter.... all codes are cleared..
  13. back2fox

    back2fox New Member

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    Surging idle after H/C/I

    I checked everything and nothing helped. I unhooked my mass air meter and finally a good idle. I rotated the position of my mass air meter about 45 degrees and plugged it back in. It finally will run on it's own. Hopefully this will help someone else.
  14. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    See item #8 on the checklist...

  15. back2fox

    back2fox New Member

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    I guess this is tue even if the air filter is mounted inside the fender.
  16. oldwantabe

    oldwantabe New Member

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    I did want to let everyone know.I checked and looked at a lot of things trying to correct the surging idle problem on my 93 coupe.It was chocking down and surginging from300 to 1600 RPM.I carried it to Bernie Prince in Bolingbroke,Ga.I watched him work on the car,he was all over the engine checking and correcting problems.In about an hour or less he had my mustang running like new.This car has a Ford E cam ,long tube headers ,trickflow intake ,GT40 heads roller rockers,and H pipe.It is very drivable now,Bernie Prince knows his stuff.They showed me also they also work on other cars and problems.I was amazed and thankful for the job well done.His shops name is Performance Center Inc.Bolingbroke,Ga.Thanks for a job well done.
  17. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    It is good that you got your problem solved and that you are happy with the results.

    However, the intent of this thread is to help the die hard Do It Yourself guys find and fix their idle problems without doing a lot of damage to their wallets. Bernie may not be accessible or affordable for them.

    I would be interested in knowing how much of the first post in the checklist you actually did. Did you thoroughly follow each and every step? Did you get to the end of the checklist without finding the problem? If so, I would like to know more about your car and what you observed as it idled. Unusual cases help to improve this tech note and help others.
  18. oldwantabe

    oldwantabe New Member

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    I replaced bad O2 sensors and checked 12 volts to O2 sensors,cleanened both 10 pin connectors twice,replaced Idle air control,checked alt.voltage output.replaced damaged vacuum lines,sprayed either looking for engine rpm changes,cleaned mass air sensor,tried a mass air sensor thanks to another person being very helpful,checked continuity from block to groung wire from ground wire to chassis from ground wire to neg post.I did all I new to do and felt comfortable doing.I new nothing about fuel inj. when I started but have learned a lot. A carb. system is very simple most times to work on and is all I have every fooled with. Reading your post and trying things was a great help to me,it was very eye opening.
    I was begining to think I needed to pull the Ford E cam out and go with another one,I do want everyone to know it seams to be a very streetable cam and can run and idle good.
    Unplugging the mass air sensor would give me a good idle but top end was bad.This does not mean it is bad though.I cleaned mine and tried another one,This could be a couple of hundred dollar mistake replacing this unit when not needed.
  19. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    What is your current idle speed?
    What was your ignition timing?
    Did you dump the codes?
    Do you have a Cold Air Intake?
    Was the MAF sensor you swapped from another Mustang that had no problems?
  20. aete2

    aete2 Founding Member

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    Great work every one this helps alot thank you !!:hail2:

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