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  1. #1

    Default 1984 3.8 CFI Idling Issues Solved!!!

    My mechanic has been stumped for several months on the continued idling issues, surging, stumbling and quitting on my 1984 Mustang Convertible with the 3.8 V6. He diagnosed and replaced parts until he finally just had to quit for awhile. He is not a mechanic that just changes parts and he is great at diagnosing issues that are hard to figure out. I have been researching the net relentlessly and ran up on an old Ford repair bulletin from days gone by. It described my problem (occuring only after the engine was hot) to a tee. It stated the culprit was likely the spacer under the throttle body. When the original spacer gets hot it shrinks causing a vacuum leak that causes all the idling issues. It specifically said to remove the stock spacer, part # E4AE-9C477-BA and replace it with a new fix, part # E6SZ-9C477-A. I ordered the new part off Ebay for less than $15 and installed it as soon as I got it...all the idling issues are solved. The old part was definitely causing the problems. I'm back on the road again! Hope this helps someone!

  2. #2
    FEP Super Member xctasy's Avatar
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    Default

    "old Ford repair bulletin"...the OFRB!. Asside from poeple like JA Cook on this forum, and The FrenchTown Flyer on another, Fords Technical Service Bulletins are the bomb. Finding an older guy who has been there, and done that, and doesn't think Fo Mo Co engineers are idiots also helps. Let me rephrase...some Fo Mo Co engineers are idiots, but they are forced to act in the best interests of the product, and FTSB's are penatant proof of engineering penance, piety, or, perhaps, patriachy.


    They are very specific, someones entirely wrong (eg flushing ATF in the Bordeux Automatics for Explorers probably killed more A4LD's a 55R's than anything else), but they are your best bet.

    Thanks for sharing.

  3. #3

    Default Good info......

    Quote Originally Posted by Oldman45 View Post
    My mechanic has been stumped for several months on the continued idling issues, surging, stumbling and quitting on my 1984 Mustang Convertible with the 3.8 V6. He diagnosed and replaced parts until he finally just had to quit for awhile. He is not a mechanic that just changes parts and he is great at diagnosing issues that are hard to figure out. I have been researching the net relentlessly and ran up on an old Ford repair bulletin from days gone by. It described my problem (occuring only after the engine was hot) to a tee. It stated the culprit was likely the spacer under the throttle body. When the original spacer gets hot it shrinks causing a vacuum leak that causes all the idling issues. It specifically said to remove the stock spacer, part # E4AE-9C477-BA and replace it with a new fix, part # E6SZ-9C477-A. I ordered the new part off Ebay for less than $15 and installed it as soon as I got it...all the idling issues are solved. The old part was definitely causing the problems. I'm back on the road again! Hope this helps someone!
    I'm filing this away in case I develop these problems in the future......thanks!

  4. #4

    Default

    For reference, I didn't take note of the part number when I was looking at that (restrictive, with steps impeding airflow around the throttle bores ) spacer under my '86 3.8's throttle body, but it was the gasket between them in my case that was cooked to a crisp, fell apart upon removal, and was what was leaking vacuum. IMHO, a spacer is a spacer is a spacer, as long as it's not butchered/broken or incredibly warped. It's the gaskets that do the vacuum sealing, and are a helluva lot cheaper. Ebay right now lists a couple spacers up for grabs, at $30+. That buys several two-barrel gaskets.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  5. #5

    Default

    A spacer that does not expand uniformly as it heats up, will make it tough for the gaskets to do their job.
    Or, if the spacer does not expand as much as it's surroundings do when it heats up, (not many things actually
    shrink as they heat up) simply replacing gaskets won't do any good.

    An '86 3.8 likely already came with an updated spacer, unlike the OP's '84.
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    2012 F150 S-Crew 4x4 5.0 "Blue Coyote"... 65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ...
    '68 Vert, Mexican block 307 4-speed... '71 Datsun 510 ...
    And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  6. #6

    Default

    Thank you all for the tip. I was experiencing the exact problem described and found the answer right here. I ordered a new spacer and installed (after cleaning up a horrid mess of carbon). Runs like a top! thanks again

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