PMS..Need help with idle

Discussion in 'Fox 5.0 Mustang Tech' started by blackcloud50, Jun 5, 2006.


  1. blackcloud50

    blackcloud50 New Member

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    I have an '04 PMS on my 93 GT and having trouble with the idle returning too slow after "blipping" the throttle. I have idle control set to "off" and it idles around 900 rpms. Hit the throttle and the rpms take too long to get back to idle (900).
     
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  2. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    See the sticky "Help me create the Surging Idle Checklist" at the top of the forum for help with your idle problems. The first post has all the updated answers. I add to the first post as new fixes and suggestions are posted.
     
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  3. blackcloud50

    blackcloud50 New Member

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    Never had this issue until PMS was installed. I am not getting any codes. All sensors are new. O2s sensor harness is, and has always been, disconneted per the tuner. I looked over checklist but I didn't see anything for "slow return" to idle. Did I miss something?
     
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  4. Daggar

    Daggar New Member

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    Try repostng in the new tuning portion of this forum. It's only recently been created but I know that there are some PMS guys in this forum that should be bale to help you out.
     
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  5. vristang

    vristang Advanced Member

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    I know absolutely nothing about the PMS, but the tweecer has a setting for how quickly the rpms return to idle (a scalar I think).
    You should have access to a similar setting, but I wouldn't know what to call it.

    jason
     
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  6. mustangsally29

    mustangsally29 New Member

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    Hey i had the same problem when i bought my car, i had a surging idle and would idle high befor going back to 850 rmps. I replaced the Idle air control valve, that stoped the surging, then after playing with the timing i got it to respond better. Believe it or not after disconecting the battery and letting the car sit for a half hour. It ran perfict! hope this helps...
     
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  7. blackcloud50

    blackcloud50 New Member

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    My idle does not surge andthe IAC is fairly new. I disconnected the battery for a full day with no change.
     
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  8. criticman

    criticman Member

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    Yep. Replace or clean out your IAC, tweak the idle screw on the throttle body. Should fix it. But as you said, didn't happen before the PMS...so may be a setting in there. Did you get it new or used? Mine was new and did not result in those issues on my '93 LX. Good luck.
     
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  9. vristang

    vristang Advanced Member

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    The name "Surging Idle Checklist" is a bit misleading.

    It will help you find solutions to all kinds of idle issues.

    It is worth a try.
     
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  10. blackcloud50

    blackcloud50 New Member

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    IAC is only 3 years old and has never gotten any oil in it. It only has about 10,000 miles on it. I got the PMS new. I've been through resetting idle and all and nothing changes.
     
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  11. blackcloud50

    blackcloud50 New Member

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    As soon as I even touch the gas (as if inching up at a light) the rpms take off too high to around 1250-1300 and then take like 5 seconds to get back down. This is not supposed to happen. It's as if the IAC is getting a signal from the ECM to stay open.
     
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  12. Grn92LX

    Grn92LX Fidanza Man! Founding Member

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    Try cleaning the IAC. If not, I would just live with it b/c its better than dealing with surging and stalling. Maybe your TB is a little dirty too and sticking?
     
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  13. blackcloud50

    blackcloud50 New Member

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    Maybe the issue is in the Accel menu. This is has to do with fuel and timing as soon as throttle position changes. No one mentioned this. I will fool around with it and see what happens
     
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  14. 88_GT_5_oh

    88_GT_5_oh Sportin' a turbo 5.0 in Canadistan

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    i had the same problem on my turbo stang.

    do this and it will be solved

    1. The car must be at operating temps. If you can't keep it idling, drive it until it reaches full water temp.
    2. Turn ON the headlights.
    3. Turn OFF any accessories, like a/c, heater, defrost.
    4. Unplug the IAC connector. The IAC is the small cylinder attached to the throttle body.

    Note: If you unplug the IAC and the engine stalls, then you know the TB was not open enough causing an over rich condition. Leave everything as is, just open-up the throttle screw a bunch so that the engine can breathe while you set the idle rpm. Restart the car, and continue with #5 below:

    5. Adjust the throttle stop screw until you have the idle rpm you desire. then shut the car off and reset your TPS
    6. Plug the IAC connector back in.

    Make sure the TPS is right

    The TPS is another issue. Generally, you want to try and get it as close to 0.97-0.98 at idle as possible. Make sure that when you open the throttle all the way it hits 4.60 volts. Now, with the advent of the 04 PMS, you can "fudge" with those numbers. If you cannot get the TPS to read under 1.00, for example, you can set the PMS to tell the EEC it is seeing idle at 1.01. You should always try to get the idle reading below 0.99, but if you cannot, then this feature is really useful. The same is true for WOT, you can use the TPS option in the PMS to set the WOT tps voltage. Say you cannot get it to read 4.6, or you want earlier WOT tuning to take effect. Then you can set the WOT to say, 4.0 volts at 30% error. There are more detailed threads on this.
     
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  15. blackcloud50

    blackcloud50 New Member

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    Did that and my issue is still there. In step #5, after setting desired rpm, I plugged the IAC back in before shutting the car off. I don't think it makes a difference.
     
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  16. 88_GT_5_oh

    88_GT_5_oh Sportin' a turbo 5.0 in Canadistan

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    did you try and turn the idle control on in the PMS? whats your combo? did you reset your TPS after you re-adjusted the throttle blade? does the screen on your PMS say "idle". when you step on the gas with the car off does the screen say WOT? put a voltmeter on the TPS and slowly open the trottle by hand and make sure the TPS signal slowly rises with the throttle till it hits ~4.60 volts
     
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  17. blackcloud50

    blackcloud50 New Member

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    Yes to all. My combo is a 306 with Vortech, H,C,I.
    To fix my initial issue I have turned idle control on but from a cold start up it idles at like 1400 for about a minute, then drops and fluctuates between 1100 and 1250 for the rest of the time until my ECT temp reaches exactly 180..then it finally drops to 900 rpms.
     
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