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  1. #1
    18 PSI Boost Mustang Matt's Avatar
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    Idle Air Control Issues

    I have an 84 that I have done the PE and 86 conversion to. Prior to the conversion I had no issues with idle. Afterwards I have had an issue related to the EGR.

    When the EGR is plugged in it idles at 2000rpm or more. There is no way to lower the screw for the throttle shaft any more than I have. I have also gone through the entire setup procedure several times. The PE was used but in known good condition, EGR has been replaced with new and then a known good one to no result. I have redone the entire wiring harness on the car but that was prior to the idle issues that I contracted after the swap. I have also replaced most of the sensors on tha car.

    I have searched and tried everything I can find on the site to no avail, any suggestions? Should I swap back to the 84 computer that was in it before and see if it fixes the issue or is this a non-ECU controlled function? In the meantime I live with the IAC unplugged.

  2. #2
    Administrator SVOeric's Avatar
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    what is your idle with the IAC unplugged ?

    you are running a stock throttlebody -- right, not a bigger one?

    There are no pin-out differences on the IAC , TPS, EGR between a TJ computer and a PE computer.

    Did you swap in a la3, or PE (cause there are EGR differences, and VAM difference which could cause your problem)

  3. #3
    18 PSI Boost Mustang Matt's Avatar
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    If you pull the IAC plug the car just dies. I can keep it running without it but to get the idle under 2000 with the IAC the throttle screw is backed all the way out.

    TB is stock, but cleaned about 500 miles ago.

    PE computer, not a T-Bird, I upped the extra cash to keep from having to play pinout games. However I cannot actually read the PE on the tag, it has been scratched up some. It is mean fast and idles very smoothly other than the RPM issues.

  4. #4
    Administrator SVOeric's Avatar
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    SVO's: 86-1C & 86-1E
    Have you run the base idle/TPS adjustment procedure ? -- they have to be set together, and you didn't mention the TPS, so I want to be sure you are going through the right procedure.

    http://www.svoca.com/forum/showthrea...s=&threadid=11

    the computer may be doing something funky to try to compensate for the base idle being set so low, and actually making it idle fast.

    There is also the posibility that the IAB is just stuck... have you swapped it, or anything?

    Have you cleaned the carbon out of the EGR?

    Also -- have you checked the computer for codes?

  5. #5
    14 PSI Boost virago34's Avatar
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    Please inform the idiots of the bunch such as myself what a PE comp is and how to obtain, cause I was gonna find a TC comp and play the pin swap game. If it is easier with the PE then Id prob like to go that rout. Thanks

    Buck

  6. #6
    OVER-BOOST!!
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    SVO's: 86 1D
    Originally posted by virago34
    Please inform the idiots of the bunch such as myself what a PE comp is and how to obtain, cause I was gonna find a TC comp and play the pin swap game. If it is easier with the PE then Id prob like to go that rout. Thanks

    Buck
    The PE computer is found only in 85.5-86 SVOs. They have the most agressive tune of any of the SVO/TC ECUs and are relatively rare given the total production of the 85.5-86 cars (less than 4000 I think). They tend to command quite a price premium as a result. TC computers in contrast are relatively inexpensive. I've seen them go for as little as $40-50.
    1986 1D - An oil return and rear end away from FINALLY being fully streetable again!
    2007 Mazda3 2.3L 5 Speed hatch

  7. #7
    18 PSI Boost Mustang Matt's Avatar
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    Sorry Mike I meant IAC not EGR on the first post. All base idle and tuning procedures have been complete to the book. TPS is set at .97 and sweeps to just under 5.0. Timing is set correctly. All interior parts of manifold and EGR, and IAC are clean. The stuff that went on was either brand new or reconditioned and cleaned to within an inch of its life. I have had this problem for several months and lived with it, check the board often to see if anything else makes sense but finally gave up and posted the problem now that I have nothing else to work on.

  8. #8
    18 PSI Boost Mustang Matt's Avatar
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    My wiring harness is not in such good shape that it will give me a code, everything else seems to be on but I cannot get it to pull a code or run the tests. I checked the codescanner on my Cobra and it works fine. EGR has been cleaned, IAB (I assume bypass instead of control?) has been swapped with known good and new to no avail. Should I just swap the processor and then chase after the woring harness? I do have a good one that I picked up since I rewired the original one so I can replace it but I would rather save it for another car if I can.

  9. #9
    18 PSI Boost Mustang Matt's Avatar
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    I guess that was the 5.0 experience of setting it at .99 religiously talking. I am in the middle of replacing the O2 sensor right now, the PO had it pretty well rounded off so I am having to remove the turbo to get it out. I will get back to you on the results after it is back up.

  10. #10
    Administrator SVOeric's Avatar
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    if you can't pull codes -- that known good PE (with the scatched out label) is worrying me...
    Eric C
    SVOCA Webmaster

  11. #11
    14 PSI Boost virago34's Avatar
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    Guys I have read that the 86 EEC is tuned back a little and actually the 85.5 is hotter than all other svo. Please some one set me straight, sorry cant remember where I saw it. I found the 86 EEC at autozone $91.00 and core. No listing for 85.5 at all. I still remember reading 86 is not as hot as 85.5, but Im going with it anyway cause it is hotter than 85 and it allows me to install the 35psi injectors. Other than a stock style K&N in my breather box and a roller follower cam I have no upgrades will this be a prob?

    Buck
    Last edited by virago34; 02-18-2005 at 04:08 PM.

  12. #12
    18 PSI Boost Mustang Matt's Avatar
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    Car is back together with no change after the idle and TPS set up. TPS is at 9.0 Just for kicks I swapped in a ZBA ECU from an 84. The idle was perfect with the IAC plugged in. Obviously the processor. Any idea what could be wrong with the ECU to make the idle so high. It was used in an open track car prior to this and the case has been opened up. The computers mapping is obviously not doing well with the 35# injectors, it seems to bog at full boost as if it is too rich, the A/F ratio shows it. Was it Autozone that has the replacement PE?

  13. #13
    Administrator SVOeric's Avatar
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    yes, I believe it was autozone

    Just for kicks, see if you can pull codes from the 84 computer you put in.
    Eric C
    SVOCA Webmaster

  14. #14
    18 PSI Boost Mustang Matt's Avatar
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    Everything works fine WITH the 84 computer.

    The PE was the problem.

    The car is actually running better with the ZBA except for in heavy throttle conditions in which it is apparent it is getting too much fuel.

    I am going after a new PE soon but will try to pull codes from this computer before I swap it out.

    The car is smelly, to the point of nausea if you get on the boost at all.

  15. #15
    18 PSI Boost Mustang Matt's Avatar
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    The PE was causing the idle issues, any ideas on that? Any way to fix it?

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