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Thread: CFI random stall on decel/quick stop when hot

  1. #1

    Default CFI random stall on decel/quick stop when hot

    Hey, need the help of you CFI gurus.
    This seems to be a common issue, but found no solution in the archieves.

    My 84 Town Car stalls randomly on deceleration or hard stops. Did not do so when I bought it and before I had worked on it (new vac lines, pulldown diaphragm, fixed vac leaks, EGR valve cleaned, coolant flush....)

    Runs smooth and quiet from cold start to long drives.


    Car throws these codes:
    KOEO code: 85 on demand; 14,41 in continuity memory.
    85 is CANP
    41 is HEGO always lean
    14 is erratic ignition PIP

    Interestingly enough I donīt have a CANP solenoid. The vacuum purge valve is controlled by the green 3port vacuum valve in the intake manifold (rear to the firewall). One side controls the CANP, the other side the heat riser valve.
    Last edited by Hillbillycat; 07-12-2021 at 05:55 AM.

  2. #2
    Lost and driftin' Arquemann's Avatar
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    Check the TFI connector, make sure the contacts are clean, well seated and the wires are in good condition. Caused an erratic pip code on mine and a random stall once when it wasnt plugged in all the way.
    1985 Mercury Grand Marquis LS, "Maisa"
    2008 BMW 530d Touring, "Femma"

  3. #3

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    That connector is secured with a zip tie from PO already. - Almost all connectors are secured that way due to broken tabs.
    Iīll clip it and check for corrosion.

    Wires:
    unplug both ends (TFI module and ECM connector) and measure resistance, right? Or is there another way to tell if the wires are good?

  4. #4
    Lost and driftin' Arquemann's Avatar
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    Not sure if it'll help but check this post:

    http://www.grandmarq.net/vb/showthre...l=1#post831919
    1985 Mercury Grand Marquis LS, "Maisa"
    2008 BMW 530d Touring, "Femma"

  5. #5
    I'm an air-conditioned gypsy gadget73's Avatar
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    The canp solenoid on these I think is in the group on the driver's side valve cover. If I'm not mistaken it runs to that thermal valve, and that switches from being connected to the canister purge valve or the heat riser flap thing. If yours is missing and just plumbed to straight vacuum all the time that could be the issue. Its not supposed to have the purge valve open constantly. that will make for quite a big vacuum leak.

    What do you get for engine running codes ?

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  6. #6

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    Yourīre right. I forgot about these three solenoid things. Theyīre there and hooked up - but wait a minute. I had that EGR valve unlugged and capped off prior to cleaning. That mustīve thrown that 85 code.

    Didnīt do any KOER tests yet for Iīm not sure how to proceed. I have the scanner but not the manual.
    Do I just hook it up, turn it on and start the engine?

  7. #7
    Lost and driftin' Arquemann's Avatar
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    Click image for larger version. 

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    Pic courtesy of matth825.
    1985 Mercury Grand Marquis LS, "Maisa"
    2008 BMW 530d Touring, "Femma"

  8. #8

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    Pulled the TFI connector. The spades inside the (new from PO) TFI module were clean but the connector end was totally green from oxidation. Hosed it down with contact cleaner spray and tired to remove as much as green stuff as possible. My dental picks came in very handy for this job.
    Will see if that cures the random stall on decel/quick stops and the code 14.
    If not Iīll have to get a new connector and get my soldering iron out......

  9. #9
    2 decades of DDing Box Panthers, now in a Whale VicCrownVic's Avatar
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    Quote Originally Posted by Hillbillycat View Post
    If not Iīll have to get a new connector and get my soldering iron out......
    The cleaning might just what you needed, but if you do go as far as replacing the TFI connector it would be a perfect time to look into doing a remote TFI setup. Although it may be a little harder to get the heatsink where you are. Typically people will cut a few fins to remotely connect the PIP pins of the TFI, but another option is to use a '92+ F150 distributor and TFI module which was a factory remote TFI setup, although requires some wiring work which is not really any more complex than replacing the stock TFI connector. http://www.grandmarq.net/vb/showthre...tor-Conversion I did end up moving the mounting location to the radiator core support when I did the '90+ air box/washer bottle install.
    Vic

    ~ 1998 Mercury Grand Marquis LS - new DD
    ~ 1991 Mercury Grand Marquis LS "The Scab" - plenty of rot, backup/summer cruiser
    ~ 1997 GMC Yukon SLT - wannabe winter DD - many issues, returning sometime in the 2020s
    ~ 1991 Mercury Grand Marquis GS "The Ice Car" - Rotting Retired Winter DD
    ~ 1989 Mercury Grand Marquis GS - Rotting Retired DD
    Gone but not forgotten:
    ~ 1988 Country Squire ~ 1987 Ford Crown Vic

  10. #10

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    Looked into the remote thing. Sounds plausible and rather easy to do, but Iīve both read and came to the conclusion that the TFI module on our Panthers is pretty much in the diret airstream of the fan. That should do some serious cooling, doesnīt it?
    Iīll wait and see if the cleaning of the contacts did the trick. Then an airduct might be a simple and quick way to check if heatīs really the problem. Someone mentioned that the remote TFI actually exposes the distributor to more air and cooling and that this is the real benefit of the mod. Cougar, Ranger and otherīs had more heat stress on the TFI/dizzy.

  11. #11
    2 decades of DDing Box Panthers, now in a Whale VicCrownVic's Avatar
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    Quote Originally Posted by Hillbillycat View Post
    Someone mentioned that the remote TFI actually exposes the distributor to more air and cooling and that this is the real benefit of the mod. Cougar, Ranger and otherīs had more heat stress on the TFI/dizzy.
    That would make sense, that it's more of a benefit to the dizzy/pickup than actually being a benefit to the TFI module itself on the panthers. Essentially getting the TFI out of the way so the remaining components can be better cooled. As I had mentioned in the thread I had linked, my suspected TFI issue was likely not the TFI at all and more likely the pickup.
    Other Ford vehicles certainly had worse conditions for keeping the TFI/dizzy cool.
    Vic

    ~ 1998 Mercury Grand Marquis LS - new DD
    ~ 1991 Mercury Grand Marquis LS "The Scab" - plenty of rot, backup/summer cruiser
    ~ 1997 GMC Yukon SLT - wannabe winter DD - many issues, returning sometime in the 2020s
    ~ 1991 Mercury Grand Marquis GS "The Ice Car" - Rotting Retired Winter DD
    ~ 1989 Mercury Grand Marquis GS - Rotting Retired DD
    Gone but not forgotten:
    ~ 1988 Country Squire ~ 1987 Ford Crown Vic

  12. #12
    I'm an air-conditioned gypsy gadget73's Avatar
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    I've run some really old TFI modules. The original on my black Mark VII went well over 200k before I replaced it. It wasn't even bad, it was actually a pickup failure, but I had already bolted the new one on by the time I realized it. I still have it around here somewhere. If the engine isn't overheating they generally last fine. The only time I actually had one die on me personally was the day after the water pump gasket blew, puked all the coolant out, and overheated the engine.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  13. #13

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    So far no stall on decel/quick stop since cleaning the TFI connector.
    Although now I have a stall after every startup now that the AC is fixed. I claim this to the throttle kicker not doing itīs job the way it should. No time to verify my guess though. Will check if it doensīt stall when starting with the ATC lever on "off" or "vent" (no AC clutch engaged).

  14. #14
    GMN Regular DerekTheGreat's Avatar
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    Cool.

    Yah I think it's good practice to turn all accessories off when you kill the engine or just before, especially the A/C.
    1985 LTD Crown Victoria - SOLD
    1988 Town Car Signature - Current Party Barge

  15. #15

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    Still stalling, so the cleaning of the connecter didnīt help:-(
    Turning off the AC for hot starting helps, as well as pressing the accelerator pedal slightly down (like in the manual suggested).

    Re the stalling:
    I can generate a stumble on smooth idling engine if I wiggle the harness at the connector - so I assume (hope) itīs only the brittle old connector that needs replacement to fix this. I have ordered a new connector.

    BUT I had the car stall last night when coasting into town (with torque converter in lockup) and shifting into neutral. It immediately stalled. I had done this to see if the higher curb idle in neutral vs. drive would prevent the stalling. It did not. So I thought it might be the lockup not disengaging.
    On the other hand it also stalls during driving around town and the trannyīs not in overdrive here.

    Had taken a close look at the mechanical linkage of the CFI throttle body and TV rod/leverage this morning. Saw that the TV lever is dragging on the throttle shaft. It looks like it was sprayed with sticky adhesive grease. Manually working the lever revelaed itīs not fully retracting by the pullback spring when throttle is off of the hot idle cam (which is the case on a hot engine). So I soaked it down with brake cleaner, working the lever to get the dirt out. Now itīs much freer. Rain stopped me from taking the car for a test spin.

    I could also think of the vacuum throttle kicker not doing itīs job quite right i.e. leaking. I can pull vacuum on this dashpot thing and the plunger extends. It DOES NOT hold vacuum, it just extrudes while a vacuum source is applied. The vacuum however is weak and it will not lift off the throttle once closed. I come to believe this is what they were designed - not to step up the throttle, but to prevent a snap shut and slowing down the closing movement.

  16. #16
    Lost and driftin' Arquemann's Avatar
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    Quote Originally Posted by Hillbillycat View Post
    I could also think of the vacuum throttle kicker not doing itīs job quite right i.e. leaking. I can pull vacuum on this dashpot thing and the plunger extends. It DOES NOT hold vacuum, it just extrudes while a vacuum source is applied.
    The throttle kicker is supposed to leak some, atleast that was what I was told here. Not sure if the throttle kicker is supposed to do anything other than raise the idle when the AC is running. When fully functioning, the plunger doesn't move much either, maybe a couple millimeters.

    I just went and tested, I unplugged the throttle kicker and coldstarted the car with the AC kompressor kicking on immediately. It started just fine (not engaged on high idle). Of course the car idled very low as it was cold, but having the AC running or not actually affected the idle speed very little, and the car had no problem staying running with no choke/high idle and the AC on withouth the throttle kicker.

    Hot or cold, my car starts wayyyyy better with some throttle input.
    1985 Mercury Grand Marquis LS, "Maisa"
    2008 BMW 530d Touring, "Femma"

  17. #17
    GMN Regular DerekTheGreat's Avatar
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    My '85 would never start hot without a smidge of throttle.
    1985 LTD Crown Victoria - SOLD
    1988 Town Car Signature - Current Party Barge

  18. #18

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    Quote Originally Posted by DerekTheGreat View Post
    My '85 would never start hot without a smidge of throttle.
    Same with mine. It likes 1/8 throttle or it’s not happy.


    Sent from my iPhone using Tapatalk

  19. #19
    I'm an air-conditioned gypsy gadget73's Avatar
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    the SEFI cars work around this by fully opening the IAC when cranking. CFI you either have to do it manually or rely on the high idle system. The throttle kicker is vacuum operated, so it can't do anything until the engine is already running. Why they didn't use an electric one I don't know, but i think that did actually show up on the late v6 CFI cars. Idle control on these is kind of goofy. You set the speed with the throttle screw, but the only way the ECM can really do anything to change engine speed is to mess with ignition timing, so I guess its worth verifying that the timing is set correctly.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  20. #20
    GMN Regular DerekTheGreat's Avatar
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    I honestly think it has to do with the TPS- like the injectors aren't firing until that extra bit of voltage. My car wouldn't even cough like a carb'd car would. I did an experiment once when I was pissed at it- I was all like, "Piece of shit.. You're either going to start or you're going to kill the starter in the process." I felt sorry for it after 20 or 30 seconds of just cranking and toe'd in the throttle. It immediately lit off at that point. I don't think I ever checked timing on that rig. Was my first old car aside from the Fury, I was still learning which direction to tighten things and how to round off nuts at that point.

    THat is goofy, and I think V6 CFI stuff had it since '84. Strange that V8's did not.
    1985 LTD Crown Victoria - SOLD
    1988 Town Car Signature - Current Party Barge

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