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  1. #1

    Default N/A 3.8 CFI woes

    For the last two weeks i've had a significant issue with the car. It'd run lean and deeply limit my speed.

    pulled codes twice: big ones were things to do with the EGR and cylinder 1 being low during the balance test.

    First thing was to clean the EGR... did that and may have forgotten to hook up the vacuum line going to the EGR. it seemed good for about an hour of driving to get to school. Car stalled out twice at two red lights due to a SUPER low idle. But that was the only issue for the most part that day. Only drove it to school and home that day, let it sit over the weekend.

    Sunday night, dad noticed I didn't hook up that vacuum line, hooked it up for my while we were adjusting my idle.

    Monday morning, I was driving to my vocational classes to take care of another small thing with the car and about three miles into the trip I went from 45 mph down to 30 almost immediately with no change in throttle input, at that point the car was warmed up. Turned around to get to my own school, couldn't get past 30 mph.

    My dad and I are stumped on this one. We haven't been able to figure this one out.


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  2. #2

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    Quote Originally Posted by 86frankenstang View Post

    My dad and I are stumped on this one. We haven't been able to figure this one out.
    by this I mean that we aren't looking to spending $80 to buy a new EGR just to drive the car for another week.

  3. #3

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    So I understand it's way down on power but are you saying you think it would run fine to California as long as you stayed under 30MPH? How did you arrive at the theory that it "runs lean"? Does it idle at all? Does it start and run fine with your foot on the gas but then lose power when put in gear? Can you rev it up freely in neutral at all?

    You can use a piece of tin to block off the EGR for free. An EGR is not capable of making your car not be able to go over 30. A bad EGR will cause surging, poor idle, possibly off idle stumble etc. but you would be able to go as fast as you wanted.
    Last edited by homer302; 10-16-2018 at 07:58 PM.

  4. #4

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    Quote Originally Posted by homer302 View Post
    So I understand it's way down on power but are you saying you think it would run fine to California as long as you stayed under 30MPH? How did you arrive at the theory that it "runs lean"? Does it idle at all? Does it start and run fine with your foot on the gas but then lose power when put in gear? Can you rev it up freely in neutral at all?

    You can use a piece of tin to block off the EGR for free. An EGR is not capable of making your car not be able to go over 30. A bad EGR will cause surging, poor idle, possibly off idle stumble etc. but you would be able to go as fast as you wanted.
    Pulled spark plugs last week. With what I know, those engines run on loops, it'll start and run fine until it gets up to temp when the ECM actually starts reading and adapting to what the sensors are telling it. I wouldn't trust it to drive all the way to California.

    Last week the idle would stumble in park, haven't noticed it at all this week.

    and here's your checklist: Starts fine cold without foot on gas, power loss in gear (will be checking trans fluid again in the morning), can rev freely in neutral. does tend to surge when i get to the speed it seems limited to.


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  5. #5

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    Your issues are the EXACT reason I am getting rid of the damn fuel injection system on my 86 convertible. That damn thing is the root of all my problems. good riddance to it!!!!

  6. #6

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    little update: took it down the road and back after having it sit in my driveway for about a week, doesn't rev freely in neutral, seems to build a misfire at around 1500 rpm, can't get past 25 mph. Luckily i'm trying to get her in my school's auto shop for the winter so i can do my 5-speed swap in comfort, I've got a spare 3.8 coming my way soon and will probably start swapping parts if needed.


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  7. #7
    FEP Member
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    Default

    Plugged exhaust?
    '89 XR-7 5 Speed
    '95 SC 5 Speed
    '91 Crown Vic P72 351W
    '95 Saturn SW2
    '85 Ford LTD Squire

  8. #8

    Default

    Coil I bet.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    Hooker Super Comp Shorty Equal Length Headers
    GT40 heads, Edelbrock 3721, K&N filter in stock dual snorkel,
    Comp cams XE254H, hypereutectic pistons, catted BBK H-pipe, full custom duals.
    3.73 rear. CS5 225/60/15 on 10 holes (street) Federal 595 rs-rr 225/45/15 on 10 holes (race)
    Everything else stock and fully functional.

  9. #9

    Default

    I say that because anything that would make the cfi cause that problem would throw codes.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    Hooker Super Comp Shorty Equal Length Headers
    GT40 heads, Edelbrock 3721, K&N filter in stock dual snorkel,
    Comp cams XE254H, hypereutectic pistons, catted BBK H-pipe, full custom duals.
    3.73 rear. CS5 225/60/15 on 10 holes (street) Federal 595 rs-rr 225/45/15 on 10 holes (race)
    Everything else stock and fully functional.

  10. #10

    Default

    Quote Originally Posted by emerygt350 View Post
    I say that because anything that would make the cfi cause that problem would throw codes.


    there are the codes from my last check.



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  11. #11

    Default

    yeah, but those codes don't make me think of the symptoms you are describing. If those were causing your issue, disconnecting the egr would actually fix them.

    although that last one might be important.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    Hooker Super Comp Shorty Equal Length Headers
    GT40 heads, Edelbrock 3721, K&N filter in stock dual snorkel,
    Comp cams XE254H, hypereutectic pistons, catted BBK H-pipe, full custom duals.
    3.73 rear. CS5 225/60/15 on 10 holes (street) Federal 595 rs-rr 225/45/15 on 10 holes (race)
    Everything else stock and fully functional.

  12. #12

    Default

    And the odd cylinder count I don't understand but could imagine a coil or cap and rotor might influence.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    Hooker Super Comp Shorty Equal Length Headers
    GT40 heads, Edelbrock 3721, K&N filter in stock dual snorkel,
    Comp cams XE254H, hypereutectic pistons, catted BBK H-pipe, full custom duals.
    3.73 rear. CS5 225/60/15 on 10 holes (street) Federal 595 rs-rr 225/45/15 on 10 holes (race)
    Everything else stock and fully functional.

  13. #13

    Default

    Quote Originally Posted by emerygt350 View Post
    although that last one might be important.
    I ran the test twice, same codes. did disconnect the vacuum line going to the EGR and plugged it with something, didn't solve the problem.

    If i can get it in one of the vocational auto shops in my area that would be ideal, but so far it's looking like i won't have much luck doing that,


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  14. #14

    Default

    Coils are so cheap, give it a shot. Check that cap too, look to see if there is bad wear patterns on the contacts.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    Hooker Super Comp Shorty Equal Length Headers
    GT40 heads, Edelbrock 3721, K&N filter in stock dual snorkel,
    Comp cams XE254H, hypereutectic pistons, catted BBK H-pipe, full custom duals.
    3.73 rear. CS5 225/60/15 on 10 holes (street) Federal 595 rs-rr 225/45/15 on 10 holes (race)
    Everything else stock and fully functional.

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