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  1. #1

    Default Low energy in dash gauges on 84

    I am beginning to suspect my temp, pressure, and fuel are all suffering from the same low energy issue. I know there is some kind of voltage reduction thing going on in those dashes. Would it result in the gauges reading low? The gas gauge does go to full but it is super slow and the low fuel light is always on.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    K&N filter in a stock dual snorkel, GT40 heads, Edelbrock 3721 intake, MSD 8456 Dist., MSD 8227 coil
    Comp cams XE254H, hypereutectic pistons
    Hooker Super Comp Shorty Equal Length Headers, catted BBK H-pipe, full custom duals
    Maximum Motorsports caster/camber plates and strut tower brace, 3.73 rear, dura grip (both Yukon)
    Ford Performance Springs, Firehawk A/S 225/55r16 on LMR TRX r390 wheels (street)
    Federal 595 rs-rr 245/40r17 and 255/40r17 on OE cobra r wheels (race)
    AOD rebuilt with a 6 clutch direct drum, Koline steels stacked with 8 clutches, Kevlar band, superior shift kit, new torque converter. --Everything else stock and fully functional.

  2. #2
    FEP Senior Member tbirdman's Avatar
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    IVR (instrument voltage regulator) ?
    If they take my stapler, then I'll set the building on fire...

    85 Mustang GT

  3. #3

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    Quote Originally Posted by tbirdman View Post
    IVR (instrument voltage regulator) ?
    That’s what I was thinking as well
    79 Zephyr, 4.6L 4v/4r70w swap, with team z front and rear suspension, 8.8 and upgraded brakes and coil overs. Running Holley Terminator X Max.

  4. #4
    FEP Senior Member tbirdman's Avatar
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    Looks like this...

    Name:  IVR.jpg
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    Located on the back of the instrument cluster.
    If they take my stapler, then I'll set the building on fire...

    85 Mustang GT

  5. #5

    Default

    Is there a way to test it?
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    K&N filter in a stock dual snorkel, GT40 heads, Edelbrock 3721 intake, MSD 8456 Dist., MSD 8227 coil
    Comp cams XE254H, hypereutectic pistons
    Hooker Super Comp Shorty Equal Length Headers, catted BBK H-pipe, full custom duals
    Maximum Motorsports caster/camber plates and strut tower brace, 3.73 rear, dura grip (both Yukon)
    Ford Performance Springs, Firehawk A/S 225/55r16 on LMR TRX r390 wheels (street)
    Federal 595 rs-rr 245/40r17 and 255/40r17 on OE cobra r wheels (race)
    AOD rebuilt with a 6 clutch direct drum, Koline steels stacked with 8 clutches, Kevlar band, superior shift kit, new torque converter. --Everything else stock and fully functional.

  6. #6
    FEP Senior Member tbirdman's Avatar
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    Some great info on IVR's in this message thread...

    http://vb.foureyedpride.com/showthre...ge-help-please
    If they take my stapler, then I'll set the building on fire...

    85 Mustang GT

  7. #7

    Default

    Thanks! I will try the grounding resistor tricks today.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    K&N filter in a stock dual snorkel, GT40 heads, Edelbrock 3721 intake, MSD 8456 Dist., MSD 8227 coil
    Comp cams XE254H, hypereutectic pistons
    Hooker Super Comp Shorty Equal Length Headers, catted BBK H-pipe, full custom duals
    Maximum Motorsports caster/camber plates and strut tower brace, 3.73 rear, dura grip (both Yukon)
    Ford Performance Springs, Firehawk A/S 225/55r16 on LMR TRX r390 wheels (street)
    Federal 595 rs-rr 245/40r17 and 255/40r17 on OE cobra r wheels (race)
    AOD rebuilt with a 6 clutch direct drum, Koline steels stacked with 8 clutches, Kevlar band, superior shift kit, new torque converter. --Everything else stock and fully functional.

  8. #8

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    Checked the gauges using the resistor trick. I think they are just old and dirty... The oil pressure gauge would register correctly with the high resistance but on low resistance it would slowly climb, stop about half way, then 'click' over to the right after a short pause (I assume overcoming the dirt or whatever).

    The temperature gauge would never go all the way into H territory unless I ran straight to ground (and then it still didn't land in the middle of the H) but registered fine with low temps.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    K&N filter in a stock dual snorkel, GT40 heads, Edelbrock 3721 intake, MSD 8456 Dist., MSD 8227 coil
    Comp cams XE254H, hypereutectic pistons
    Hooker Super Comp Shorty Equal Length Headers, catted BBK H-pipe, full custom duals
    Maximum Motorsports caster/camber plates and strut tower brace, 3.73 rear, dura grip (both Yukon)
    Ford Performance Springs, Firehawk A/S 225/55r16 on LMR TRX r390 wheels (street)
    Federal 595 rs-rr 245/40r17 and 255/40r17 on OE cobra r wheels (race)
    AOD rebuilt with a 6 clutch direct drum, Koline steels stacked with 8 clutches, Kevlar band, superior shift kit, new torque converter. --Everything else stock and fully functional.

  9. #9
    FEP Member 0F0 CBR's Avatar
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    I also have the floating gauge reading issue and a temp gauge that never gets past "N" on the scale, while I am waiting on a IVR to arrive, decided to see what the engine temp was actually running at.
    Borrowed the temperature camera from work and took some IR images.

    You can see the point at which the thermostat opens and coolant starts entering the rad.
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    80.7 degC (177 degF) at the rad inlet. - Must be a 180F Thermostat
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    Took it out for a rip to warm it up and retook the images.
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    Hottest spots are 91C or 196F
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    What is the temp range of a 1980 gauge in the "Normal" zone?

  10. #10

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    Wow
    that is really cool
    or should I say hot?
    79 Zephyr, 4.6L 4v/4r70w swap, with team z front and rear suspension, 8.8 and upgraded brakes and coil overs. Running Holley Terminator X Max.

  11. #11
    FEP Member 0F0 CBR's Avatar
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    ttt
    What is the temp range of a 1980 gauge in the "Normal" zone?

    Has anyone had any luck with the aftermarket instrument voltage regulators? I put a new one in and all the gauges read 25% lower than before. Ripped the dash apart again and put my old one back in. Went for a drive and speedometer did not work, ripped it apart again and got the cable installed all the way on this time.
    Decided I can live with 3/4 full gas tank reading even after fill-up.






  12. #12
    FEP Member Hans's Avatar
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    My gauge is at the 'l' with the 195F thermostat. 1979 V8 if that matters.
    Previous 195F thermostat was also in that region.


    Verstuurd vanaf mijn ALE-L21 met Tapatalk

  13. #13
    Moderator wraithracing's Avatar
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    If you look closely at the gauges in a Fox dash (79-86) the needle is literally not much thicker than a sheet of paper and is easy to tweak just by touching it. If the gauge cover has ever been removed and even the gauges cleaned it can tweak where the needle sits at any specific temperature. Not that the gauges were ever very accurate nor consistent to begin with. Same is true for most of the Ford and others gauges of the era. Personally I would drive the car and get it up to temperature and see where the needle reads and just remember that is standard operating temperature for whatever thermostat you have installed. I have had Foxes that the needle has read anywhere from O to A on the "NORMAL" gauge and all of them had at least a 180 thermostat.
    ​Trey

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  14. #14
    FEP Super Member gr79's Avatar
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    Thanks for posting FLIR pics. Never seen that done on our cars. IR readings yes, FLIR no.
    I guess you need an app and ext camera to do this on a smartphone.

    If the low fuel LED is always on, may be because a black right angle wire connector is not plugged onto a stud that holds the temp gauge.
    If your model has the same setup as my 79 with LED console warning display.
    Happens when the cluster is removed. When cluster is pulled forward, the hidden black connector pops off the ground stud.
    Believe it goes on the innermost stub of the two that fastens the temp gauge to the cluster. I forget.
    One would never see this disconnection happen. Is a short wire and hard to get at.
    Once discovered, is left loose as a 'what is this wire'? Was it always hanging loose?
    Or, once aware of its function, is disconnected per procedure and forgotten about being reconnected during cluster reinstall.
    Would be hanging loose behind the cluster, to the right of the warning light wiring, near the temp gauge and circuit ribbons.
    Similar small gauge wire, with round shaped push on black right angle ele connector, is found else-ware on temp and oil sensors and the fender starter solenoid.
    Reconnected, low fuel light functions normal again.

    Sometimes, also, when the low fuel LED light is on, tank has plenty of fuel, and the cluster wire is plugged in:
    Key on to power up cluster and display, I reach into the area behind and above the glove box light and push wiggle wires.
    When i push the right one, the LED goes out every time. Must go to the low fuel module connector.
    Been that way forever.
    Last edited by gr79; 11-01-2020 at 08:04 PM.

  15. #15
    FEP Super Member gr79's Avatar
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    Filled the tank yesterday.
    As usual, the gauge read 7/8 for 15 miles then pegged to F.
    Currently is down to 3/4 tank after 70 miles.
    Sometimes will park car, then next time started fuel gauge will read a bit higher or lower that before.
    Gas needle always moves 1/8 tank toward the inside of turn and settles back after a 1/2 mile.
    Or getting off freeway, gauge will read a bit lower afterward.
    Just when you think you just got great fuel mileage on that run.
    When driving, am assuming unknown causes affect the IVR to move the temp, fuel, oil press a bit high or low.

    My Ranger has an 270 sweep autometer temp gauge. Comparing up and down to the stock gauge is not quite linear.
    Low mark to N of NORMAL is approx 195, O 200, R 210 M 220 A 230. Never drove it reading past A.
    Happened couple times over the years at low speeds. Fan clutchs and front cab mounts. Ok now.

    Both rides here are 2.3 and read the same way. Usually N, or just inside N zone. Stock Motorcraft thermostats.
    Car has straight drive 5 blade metal flex fan, truck has plastic clutch fan.
    In very hot humid weather they may creep up to 200-210 (O-R) sitting at a long light or in heavy traffic.
    My LTD LX 5.0 never ran lower than 1/2 way once warmed up.
    Last edited by gr79; 11-01-2020 at 08:51 PM.

  16. #16
    FEP Member 0F0 CBR's Avatar
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    Thanks for the info, I do have that "black mystery" wire behind the cluster, I wondered where it went, and did not plug it in. My low fuel light is not on.
    Looking at the Haynes manual it is only shown for 1979, connector C-519. The 1980 schematic does not show it.

  17. #17

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    GR79!!! You are the best! I have had that stuck fuel light and had no clue about that stupid black elbow. I want to replace the IVR again so that gives me an excuse to pull the cluster back out again.

    I have noticed that my cluster oil pressure gauge wanders stupidly while my mechanical oil pressure gauge behaves predictably every time.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    K&N filter in a stock dual snorkel, GT40 heads, Edelbrock 3721 intake, MSD 8456 Dist., MSD 8227 coil
    Comp cams XE254H, hypereutectic pistons
    Hooker Super Comp Shorty Equal Length Headers, catted BBK H-pipe, full custom duals
    Maximum Motorsports caster/camber plates and strut tower brace, 3.73 rear, dura grip (both Yukon)
    Ford Performance Springs, Firehawk A/S 225/55r16 on LMR TRX r390 wheels (street)
    Federal 595 rs-rr 245/40r17 and 255/40r17 on OE cobra r wheels (race)
    AOD rebuilt with a 6 clutch direct drum, Koline steels stacked with 8 clutches, Kevlar band, superior shift kit, new torque converter. --Everything else stock and fully functional.

  18. #18

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    Well.... pulled it off but no black elbow. Perhaps by 84 those were gone.
    1984.5 G.T.350 5.0 CFI AOD Convertible (TRX package, loaded)
    K&N filter in a stock dual snorkel, GT40 heads, Edelbrock 3721 intake, MSD 8456 Dist., MSD 8227 coil
    Comp cams XE254H, hypereutectic pistons
    Hooker Super Comp Shorty Equal Length Headers, catted BBK H-pipe, full custom duals
    Maximum Motorsports caster/camber plates and strut tower brace, 3.73 rear, dura grip (both Yukon)
    Ford Performance Springs, Firehawk A/S 225/55r16 on LMR TRX r390 wheels (street)
    Federal 595 rs-rr 245/40r17 and 255/40r17 on OE cobra r wheels (race)
    AOD rebuilt with a 6 clutch direct drum, Koline steels stacked with 8 clutches, Kevlar band, superior shift kit, new torque converter. --Everything else stock and fully functional.

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