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  1. #1

    Default 85 LTD LX... failed smog...HELP!

    Ok guys.... for you LTD LX owners... This is my first FI car (kinda)and I had it tested and it failed smog due to hi HC... can you all help me figure out whats wrong so I don't have to pay 65 bux to hook it up to a computer?

    thanks!

    Jasen
    1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD.
    Cardomain: http://www.cardomain.com/ride/565542
    Mid Size LTD LX Facebook page! http://www.facebook.com/groups/233213650060739/

  2. #2

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    Hey Marz - my LTD LX just passed this week with 156 K miles, had 62 ppm HC vs 100 ppm limit, and only 0.01% CO.

    Couple of tricks I have used the last several years - first, change to fresh oil they day of, or the day before the test. This tightens up the piston ring seal and whatevers left of the valve guide seals.

    Second, drive the car there in second gear to get the converter(s) really hot.

    How high was your HC? Is this an idle test or on the rollers? When you blip the throttle in neutral to 3 krpm or so and take your foot off, does it backfire very lightly? If none at all something may be wrong with the air diverter valve. either the valve iteself or the TAD/TAB soleniods. On the 85 LTD LX they come in pairs, I think there is only 6 or so left new in the U.S., check out greensalescompany.com.

    Anyhow, post your HC, CO and NOx and we'll figure it out. Retarded timing can cause high HC as well.

    Other thing I did fairly recently was run a full bottle of Redline injector cleaner through mine (Chevron Techron works as well, nothing else does though). The inside of my intake looks brand new.

    zak
    1985 LTD LX original owner

  3. #3
    FEP Power Member LTDScott's Avatar
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    Always had trouble passing smog with that car. Post numbers.

    I got it to barely sneak by once by retarding the timing to like 6*, turning down the fuel pressure, changing the oil, and making sure it was really hot.

    Two years later I had to install a new cat, heh. Throw a new cat on nearly any car and it'll pass.
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  4. #4

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    OK... heres the #'s:

    CO2_O2____________HC________________CO
    ____________Max___Ave__Meas_Max__Ave___Meas
    12.5__3.5____133____41___147_.82_.13___.07
    12.1__3.8____108____29___139_.62_.11___.13

    ______NO
    Max__Ave__Meas
    1125__399__145__<--- Taken @ 15mph @ 1412rpm
    955___332__116__<--- Taken @ 25mph @ 1928rpm



    There ya go

    Eh... ignore all the _ signs... that the only way it'd post correct.


    The fact that it's a B!@ch to pass nearly every time means that theres something wrong with the car... and it needs to be fixed. It shouldn't be this difficult for it to pass.

    I do know that the car feels a little jumpy when driven... according to James Petersons site... I think the TFI modual may be causing that. Could that have anything to do with it not wanting to pass smog?
    1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD.
    Cardomain: http://www.cardomain.com/ride/565542
    Mid Size LTD LX Facebook page! http://www.facebook.com/groups/233213650060739/

  5. #5

    Default TFI could do it

    As they go bad you get more and more misfiring. Any misfire sends HC through the roof. You need a special tool to change it, if it is hesitating or stuttering it needs to be changed. Usually worse when warm.

    Basically Motorola ended up with an air bubble right at the main power transistor in these TFI's, which insulates it instead of conducting heat away.

    zak
    1985 LTD LX original owner

  6. #6

    Default Re: TFI could do it

    Quote Originally Posted by zak
    As they go bad you get more and more misfiring. Any misfire sends HC through the roof. You need a special tool to change it, if it is hesitating or stuttering it needs to be changed. Usually worse when warm.

    Basically Motorola ended up with an air bubble right at the main power transistor in these TFI's, which insulates it instead of conducting heat away.

    zak
    So... if I got you Right, your saying what I've been thinking... right? That the TFI modual is the problem if not part of the problem?

    Also James Peterson had talked about moving the TFI modual away from the distributor by using what I seem to remember being a T-bird harness and heatsink... But not sure. But... I already have the heat sink just not harness!

    Thanks!
    1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD.
    Cardomain: http://www.cardomain.com/ride/565542
    Mid Size LTD LX Facebook page! http://www.facebook.com/groups/233213650060739/

  7. #7

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    I noticed your O2 is way high. My hunch is your cats are dead again. The question is (if my hunch is true) what caused the cats to go?

    Dean T
    Proud owner of the one and only Friggin' Futura

  8. #8

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    Quote Originally Posted by Dean_T
    I noticed your O2 is way high. My hunch is your cats are dead again. The question is (if my hunch is true) what caused the cats to go?

    Dean T
    Yeah... I wanted to get that checked on Saturday... but for some reason my exhaust guy was closed.

    I would indeed like to find out what killed the cat. Once I fix what ever problem this car has I don't believe it'll keep killing cats. You shouldn't have to replace the cat every 2 to 4 years.
    1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD.
    Cardomain: http://www.cardomain.com/ride/565542
    Mid Size LTD LX Facebook page! http://www.facebook.com/groups/233213650060739/

  9. #9
    FEP Super Member anthonydalrymple's Avatar
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    If you indeed replace the cat; have you considered making\buying a no-cat pipe to sub in for daily driving? I have a Magnaflow catted x hanging on the garage wall with only one purpose in life; to install for smog testing purposes....
    '89 5.0 5-speed 'vert, seeing rust for the 1st time in it's life as well as 4,500+ elevation....

  10. #10

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    Quote Originally Posted by anthonydalrymple
    If you indeed replace the cat; have you considered making\buying a no-cat pipe to sub in for daily driving? I have a Magnaflow catted x hanging on the garage wall with only one purpose in life; to install for smog testing purposes....
    Thats a good thought....

    I have been cocidering it... and for this car I mat just do that.
    1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD.
    Cardomain: http://www.cardomain.com/ride/565542
    Mid Size LTD LX Facebook page! http://www.facebook.com/groups/233213650060739/

  11. #11
    FEP Power Member LTDScott's Avatar
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    Quote Originally Posted by anthonydalrymple
    If you indeed replace the cat; have you considered making\buying a no-cat pipe to sub in for daily driving? I have a Magnaflow catted x hanging on the garage wall with only one purpose in life; to install for smog testing purposes....
    He'd have to have a muffler shop weld in flanges to do that. Any shop that doesn't want to get fined up the butt probably won't do that.

    Here is the a/f ratio from this car when it was last dynoed.



    http://dynoperformance.com/jpgraph/g...680&height=450

    It's clear that it's running lean. Check fuel pressure, and maybe replace the O2 sensor.[/img]
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  12. #12

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    That graph was from the car I currently own?

    Also, I do have a shop that'll gut the current cat (if it's shot) and toss an new one on new flanges in it's place for me.

    Then when it comes down to smoging it... All I have to do is swap the gutted one for the good one.

    But I'll check that O2 sensor and the fuel pressure. Also. NGK plus were in this thing... maybe I should toss a set of Autolite 25's in it instead?

    Also, changing the O2 sensor would get rid of it being lean? Checking the fuel pump too?

    These "new" computerized FI cars are forign to me... I wanna learn about these things!
    1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD.
    Cardomain: http://www.cardomain.com/ride/565542
    Mid Size LTD LX Facebook page! http://www.facebook.com/groups/233213650060739/

  13. #13

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    HC = Hydrocarbons are unburned gasoline particles that contribute to the formation of ground level ozone. Gasoline is hydrocarbon compound.

    CO = Carbon monoxide is a colorless, odorless gas formed from partially burned fuel. CO is formed when the combustion process is less than complete, usually due to a rich air/fuel mixture.

    CO2 = Carbon Dioxide. efficiently of exhaust. Ideal condition is 13-17 percent. Higher CO2 percentage the more efficienlty the vehicle is running.

    O2 = Oxygen of exhaust. Not O2 sensors! O2 work together with CO. When CO is low or high the O2 percentage can tell you the richness or leanness of the A/F mixture.

    NOX = Oxides of Nitrogen. NOx form during the combustion process when engine temperatures exceed 2500°F.

    If you're running lean then your NOX level will skyrocket.

    Bottom line...You're running way too rich.
    Look at NOX level and HC level. High HC level diluted the NOX level. Raw fuel cooled the combustion process.

    Find out why you're running rich, not lean. This may causes your cat converter to failed. Exceesive usage of rich A/F misture will destroy cat converter.

  14. #14
    FEP Power Member LTDScott's Avatar
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    Quote Originally Posted by Marz
    That graph was from the car I currently own?
    Yes this is your car. Obviously the graph is at WOT, so maybe at WOT it's lean and at low speed cruise (IE smog test speeds) it's rich. Generally the CO will be high as well as the HC if you're running rich, though.
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  15. #15

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    Quote Originally Posted by LTDScott
    Quote Originally Posted by Marz
    That graph was from the car I currently own?
    Yes this is your car. Obviously the graph is at WOT, so maybe at WOT it's lean and at low speed cruise (IE smog test speeds) it's rich. Generally the CO will be high as well as the HC if you're running rich, though.

    something isn't right here...

    W.O.T on emission testing?


    the graph you posted is for Performance Dyno run not emission testing isn't it?

  16. #16

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    that graph is from when it was dyno'd
    1984 LTD Wagon - S3AHAUS
    1988 Mustang LX 5.0 Hatchback - NOBIMMR
    1997 BMW 318ti - TinyBimmer
    2001 BMW 325i Wagon - ANTICW

  17. #17
    FEP Power Member LTDScott's Avatar
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    Quote Originally Posted by Old_Timer

    the graph you posted is for Performance Dyno run not emission testing isn't it?
    Yes.
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  18. #18

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    Well it passed smog with a new cat.

    I had forgotten that I had a cat laying around that would fit the LX's 3" exhaust. This was originally intended for the Futura... but cause of the accedent... it was never used.

    I can now work on fixing the surging...
    1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD.
    Cardomain: http://www.cardomain.com/ride/565542
    Mid Size LTD LX Facebook page! http://www.facebook.com/groups/233213650060739/

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