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Technical => Misc Tech => Topic started by: Muiscmaster on September 16, 2018, 01:51:44 PM

Title: 84 Tbird temp gauge
Post by: Muiscmaster on September 16, 2018, 01:51:44 PM
I have an 84 TBird. There is a temperature sensor on the engine but I don't see a temp gauge anywhere on the gauge cluster. Also, my speedometer/odometer reads too fast. I have 70 actual miles on my external trip meter and the one on the dash shows 114.
Title: 84 Tbird temp gauge
Post by: Haystack on September 16, 2018, 02:27:06 PM
What part of Nevada?

Yeah, these cars are pretty sparse on gauges. I'm assuming you have a 302? If so the computer needs to know temps, but I guess ford decided you don't.

As far as the trip computer, they should both get the same input, I'm not sure how they could read differently unless they weren't reset at the same time?
Title: 84 Tbird temp gauge
Post by: Muiscmaster on September 16, 2018, 03:11:07 PM
What I mean by external trip meter is my GPS. I recorded a trip over the span of a week and the odometer reeds more miles than it should. The speedo is fast too. 55 MPH reads as 67 on the dash. Is there a way to calibrate that? I don't know much about these. I only got it because it was cheap. It's a 5.0. as far as the temp gauge goes, I suppose I could get an aftermarket gauge
Title: 84 Tbird temp gauge
Post by: EricCoolCats on September 16, 2018, 03:35:18 PM
The 1983-84 base cluster did not have a temp gauge, just the warning light. You speedo is off likely because of a taller tire or other tire change beyond stock. It can be corrected with a speedo gear change at the transmission.
Title: 84 Tbird temp gauge
Post by: Muiscmaster on September 16, 2018, 07:25:18 PM
Where could I find the correct speedo? Rockauto? The tires appear to be factory size but i will have to research to confirm
Title: 84 Tbird temp gauge
Post by: Muiscmaster on September 16, 2018, 07:46:08 PM
I found a website that has several different speedometer gears ranging from 16-24 teeth. Does anybody know how many teeth the original has and what type of transmission is in the 84? Thanks, sorry for all the questions.
Title: 84 Tbird temp gauge
Post by: softtouch on September 17, 2018, 04:26:55 PM
The RED "Engine" light is a dual purpose, Overtemperature/Low oil pressure, warning light.
The tire pressure decal on the passenger side door jam will show the stock tire sizes.
The decal on the drivers side door jam has the codes for what drive train the car was built with. Engine, trans and rear end gear ratio.
Title: 84 Tbird temp gauge
Post by: softtouch on September 17, 2018, 04:53:27 PM
My 84 3.8L V6 came with P195/75R14 tires.

How to check your axle ratio.
https://shiftsst.com/articles/how-to-determine-the-rear-axle-ratio
Title: 84 Tbird temp gauge
Post by: Muiscmaster on September 17, 2018, 11:12:27 PM
The tires that are on there are slightly bigger than factory specs, which would cause the speedo to read slower. Ill try a different gear or speedo sender. For now i'll just keep using my GPS.
Title: 84 Tbird temp gauge
Post by: Muiscmaster on September 17, 2018, 11:13:41 PM
How do I know what the red engine light is indicating? The previous owner scanned it and it said bad EGR, so he replaced it and the light is still on
Title: 84 Tbird temp gauge
Post by: softtouch on September 18, 2018, 12:44:08 AM
Quote from: Muiscmaster;467129
How do I know what the red engine light is indicating? The previous owner scanned it and it said bad EGR, so he replaced it and the light is still on

The light is normally on when you turn the key on without starting (no oil pressure). Then goes off after starting and oil pressure comes up.
To isolate which is bad, pull the wires off the sensors (actually switches).

Oil pressure switch has one wire (white/red stripe) and is near the oil filter.
Temp. switch has one wire (red/white stripe) and is in the intake manifold. Near the distributor. I think.

Temp sensor has two wires (light green/yellow stripe & black/white stripe) also in the intake manifold. I think. This is used by the ECU and does not turn on the red light.
Title: 84 Tbird temp gauge
Post by: Muiscmaster on September 20, 2018, 12:43:07 AM
Thanks for the diagram
Title: 84 Tbird temp gauge
Post by: fordman3 on September 20, 2018, 06:31:16 PM
Musicmaster,
Going off of what you said about the car going 67 when your speedo only says 55 (I think that's the order you gave), that's an overage of around 22%.  That would mean you were running a tire that was 22% larger in diameter than stock.  That would be around a 31" truck tire.  I don't think there's any way your variation is completely due to tire size.  How likely is it that someone has swapped gears in the rear end?  Or put an AOD in it when it originally had a 3sp?  That's just a big variation.  That's more than most of the 4x4 guys deal with when they go to way-oversized tires without correcting their speedo's.  I've got 32" tires on my 2wd truck and it should have 30.5", so that's a 5% increase.  At 67 indicated on the speedo, I'm really going 70 by the GPS.  Let us know if you figure out what's really throwing it off.  Later.
Title: 84 Tbird temp gauge
Post by: fordman3 on September 20, 2018, 06:44:43 PM
Well, I re-read your earlier post, and I had the order backward.  So everything should be opposite from what I said earlier.  Your speedo is showing 22% too high.  That logic says you're running a tire that's 22% too small in diameter.  That too is almost an impossibility, and you already said your tires were slightly taller than stock.  I'm betting you've had lower gears installed in the rear, and the speedo was never corrected.  Or you've got a 3sp trans when it should have been an AOD.  Someone else confirm that my logic is going in the right direction.  Maybe some of this helped....
Title: 84 Tbird temp gauge
Post by: Muiscmaster on September 23, 2018, 05:10:17 PM
The current tires are slightly larger than factory specs so none of this makes any sense. Are these cable driven speedos?
Title: 84 Tbird temp gauge
Post by: Haystack on September 23, 2018, 06:50:17 PM
The Speedo is digital on the 85-88 years, mechanical on the 83-84 years (with digital being an option)

And you can order gears just like you can with a mustang. Pop out the speed sensor(or Speedo cable) pop off the old gear and install a new one. Its really not that hard or expensive if it bugs ya that much.