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79 elderado

Started by Tamuiel, March 01, 2021, 09:44:28 PM

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Tamuiel

1979 elderado..can i add the mpg feature that comes as an option.. thanks in advance

James Landi

The Miles Per gallon digital readout on the newer versions are nothing more than a digitized vacuum gauge...  I had the dash apart on two newer Eldorados years ago that I owned and loved, and was surprised, and frankly disappointed, to see a vacuum hose going to the dash mounted digital mpg read out.  So, if you can find a newer dash, and if your '79 has a plastic filler that is sized to fit the instrument, it shouldn't be a big deal to retrofit one. Since the instrument is entirely sealed, any vacuum line you tee off of will provide you with a reading. And by the way, you have the vastly more durable drive train in your 79-- care for it ,and love it since the alternative 4100 HT suffered from so many failures.    Hope this helps. James

TJ Hopland

I assume you are speaking of the LED light that would change colors to tell you if you are getting good or bad economy?  If so I thought the brains of that system was a module under the hood that had the vacuum line connected to it?

Or are you saying the actual digital readout trip computer found on the DEFI systems starting in 80 was a stand alone system not tied to the ECU also?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

smokuspollutus

The digital mpg display is controlled by the ECU, which the analog fuel injection on your car cannot support.

James Landi

THe ecm does not control the digital readout for the Miles Per Gallon-- that is simply a digital read out of the vacuum manifold pressure.  Regarding the "Range" computer and number of gallons in the tank computer, I never got into that.  I believe the gentleman's question was limited to the MPG readout.   On some of the 80's Cadillacs, there were differing gauge cluster arrangements, so he'll need to be a bit more specific with his question. As always, respectfully attempting to be helpful, but always prepared to learn more than I already know... Happy day,  James

TJ Hopland

Page 10 mentions the trip computer with 16 changes to make it better.    I don't know that I have even seen pictures of this unit before,  for sure never seen one in person.   All I ever saw was the simple colored light or the later DEFI system that was much smaller and only a 3 digit display and 3? buttons.   This one looks a little more complex.   

https://www.modifiedcadillac.org/documents/1970s/1979/1979%20Roundtable%20Features/tn/79%20Roundtable%20Features%20-%2010.jpg.html

page 15 of this one mentions it but no pictures.

https://www.modifiedcadillac.org/documents/1970s/1979/1979%20Sales%20Brochure/tn/79%20Sales-15.jpg.html
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

smokuspollutus

Hi James, I think you might be confusing the MPG display with something else-perhaps the MAP sensor which is located nearby in the dashboard and does have a vacuum line running to it. But the MPG panel does not have any direct vacuum inputs. The bulk of it’s information comes from the throttle position sensor, and is complemented by the other engine data (coolant temp, MAP readout, vehicle speed,etc) in the computer to give the driver an idea about the instant MPG.

This is all very different from a 1979 with the analog fuel injection system. Though there was an option in that year for a digital speedometer in both the Eldo and Seville that could provide this kind of information, it was set up in a completely different way. A little more “gimmicky” than the setup used in the later years, it was still a very cool option. I have seen a several Sevilles with it, but only 2 Eldorados.

So in short, no, an 80+ fuel data display can’t be swapped in to the 1979.

Respectfully,

Anthony

TJ Hopland

If anyone has a manual they can scan or even better knows of maybe an official training video that has been uploaded somewhere on how to 'drive' that 1979 system I for one would love to see it.   Looks like a fairly complex operation with a lot of buttons and levers.   There must have been an official GM/Cadillac training film on that system,  hope it still survives somewhere. 

Was that info in the regular owners manual or was it likely a supplement if you got that option? 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

TJ Hopland

Here is some info on the system that came with the DEFI cars which were federal Eldo and Seville in 80 then most cars in 81.

https://www.modifiedcadillac.org/documents/1980s/1981/1981%20DEFI%20Train/tn/1981%20DEFI%20Train-32.jpg.html

It says the brains for the MPG display are in the climate control head which was digital starting in 80.   It says the climate control gets its info from the DEFI ECM and the 'range module' which is an additional unit under the dash.  I can't find a way to zoom in enough to read the pinout labels in the document,  I am very curious what they are.   The range module must take some extra sensors in like say fuel level since the regular ECU would not care about that and maybe also has the memory in it since the main ECU isn't really storing much if any data.   Why did they tie this into the climate control too?   Why not put it all in the range module?   I may have to go searching for my 81 manual to see what it has to say about the ins and outs of that system

Since it appears that much of the system doesn't depend on the engine ECU I wonder why it wasn't available with the carbs too since by then those had computers?   Maybe Cadillac didn't expect to sell enough carb engines to make it worth the extra development work so for their carb cars they were more or less using off the shelf GM stuff and since no one else wanted the trip computer at the time it was just never adapted? 

Photo is of an 81 system but I think it was more or less the same later they just got rid of the active cylinder button which was only for the V864 engines.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

smokuspollutus

The MPG computer got a little more sophisticated as time went on, with range calculations and the like. The ECM was the catch all for all the information. The carburetor cars never got them because there was still no way to figure out exactly how much gas was going into the engine. With fuel injection, the computer could “know” by the pulse width of the injector times the pre determined flow of the injector that was supposed to be on that type of engine.

TJ Hopland

The carbs had a mixture control solenoid and its position would give the system and idea if things were operating as expected so you would think they could make a pretty good guess how things were running.   All the rest of the inputs would have been there.   Had to be a pretty similar setup on that earlier system that went with the analog EFI.

Guess we will have to wait for James to come back and give us more details about the specific systems he was messing with that appeared to be self contained.   I have been into the dash of 4100 cars and one 81 but was never specifically working on the MPG computer so never paid attention to what was hooked where.   By 81 there was a few million wires and hoses under the dash so you can't really tell anything by just looking,  you pretty much have to have a schematic and be tracing a specific wire or hose to make any sense of what is under there.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Tamuiel

Thank you all. I believe it cones on the biarritz standard. Now I have the car and am starting to fix some things. I had an 83 in my late 20’s with the junk 4100 (blew it up). Just can’t beat that cadi ride! Smoooooth!  I ordered a blower relay cuz no blower except on defrost and no brake light so im starting at the switch. I also own an 07 cts. My first car at 15 was a 78 coupe de ville. Im sure ill be on here often in the coming months!! Oh yeah she starts hard when cold, im hearing some coolant sensor. Thanks all!!! My name is Tamuiel 47

79 Eldorado

#12
Tamuiel,
My car is a '79 Biarritz. It has 2 small lights lower left within the instrument panel but nothing else. I couldn't find an exact replacement bulb and one of mine was simply burned out. To replace it I needed to put the bulb in from the front and the socket from the back. They closest new bulb I found wouldn't fit from the socket side. See photos. The green bulb means fuel economy is good and amber fuel economy is not. These 2 bulbs are the same style but much smaller than the standard 194 dash bulbs.

My notes say according to the Service manual the bulb should be nr 161 but 161 is the size of 194; instead I used nr 24. The socket end is the same size but the filament is too large to go in the back.

I created a replacement for the coolant and air temp sensors and recently for the Fast Idle valve "FIV" heater.

Scott

79 Eldorado

Quote from: TJ Hopland on March 02, 2021, 01:36:13 PM
If anyone has a manual they can scan or even better knows of maybe an official training video that has been uploaded somewhere on how to 'drive' that 1979 system I for one would love to see it.   Looks like a fairly complex operation with a lot of buttons and levers.   There must have been an official GM/Cadillac training film on that system,  hope it still survives somewhere. 

Was that info in the regular owners manual or was it likely a supplement if you got that option?
I found a video on youtube. I thought I would post a link for others. I am just starting to watch it "1979 Cadillac Trip Computer - Tripmaster"
https://www.youtube.com/watch?v=1ZXCUYkC17A

Scott

bcroe

Quote from: 79 Eldorado. I found a video on youtube. I thought I would post a
link for others. I am just starting to watch it "1979 Cadillac Trip Computer - Tripmaster"
https://www.youtube.com/watch?v=1ZXCUYkC17A.  Scott.

I love those punched cards and other technology that I worked on at
the beginning of my career, and were mostly obsolete even at the time
of this video. 

With 79/80/81/82 each having a different engine setup and electronics
changing fast, that mpg setup would tend to be one year only designs,
unless it was totally independent of the rest of the car.  ZEMPCO did make
such a system, monitored injector pulse width and driveshaft rotations. 

Hope a relay fixes your blower, sometimes it burns out the Climate Control
board.  I put a 79 Eldo fix for that in July 1999 Self Starter.  Solution to a
similar problem with the 76-79 EFI fuel pump is solved in the SS Nov/Dec
2010 issue.  good luck, Bruce (79 Eldo owner for 26 years) Roe

Daryl Chesterman

QuoteMy notes say according to the Service manual the bulb should be nr 161 but 161 is the size of 194; instead I used nr 24. The socket end is the same size but the filament is too large to go in the back.

Scott, I sent you a PM about the above quote, but you might try a #73 mini wedge-base bulb as it has a diameter of .22 inches.  NAPA's part number is 73N.

Daryl Chesterman

79 Eldorado

Quote from: Daryl Chesterman on April 04, 2021, 06:28:20 PM
Scott, I sent you a PM about the above quote, but you might try a #73 mini wedge-base bulb as it has a diameter of .22 inches.  NAPA's part number is 73N.

Daryl Chesterman
Hi Daryl,
Wow, thanks! That looks like it could be the correct size. How did you end-up figuring it out? There was no number on mine, the reference I found was wrong, and so was the reference the part store had. I'm glad you replied here as well because possibly that will help others.

Thanks again,
Scott

79 Eldorado

Quote from: bcroe on April 04, 2021, 04:55:07 PM
I love those punched cards and other technology that I worked on at the beginning of my career, and were mostly obsolete even at the time of this video. 
I did find that funny as well. I was thinking the same that those card may have been obsolete by then.

Quote from: bcroe on April 04, 2021, 04:55:07 PM
With 79/80/81/82 each having a different engine setup and electronics changing fast, that mpg setup would tend to be one year only designs, unless it was totally independent of the rest of the car.  ZEMPCO did make
such a system, monitored injector pulse width and driveshaft rotations. 
I was really curious as to what the system looked like. You will never believe it but someone in the Netherlands has a complete system, and yes I mean complete even down to the sun visor with a sticker showing the Tripmaster information on it, on eBay for sale currently. I'm really glad my car did NOT have the system because I'm sure I would feel the urge to repair it but what an interesting piece of technology. I'll post the photos I saved as I suspect the person selling on eBay wouldn't mind as we are likely their target market!

Quote from: bcroe on April 04, 2021, 04:55:07 PM
Hope a relay fixes your blower, sometimes it burns out the Climate Control board.  I put a 79 Eldo fix for that in July 1999 Self Starter.  Solution to a similar problem with the 76-79 EFI fuel pump is solved in the SS Nov/Dec
2010 issue.  good luck, Bruce (79 Eldo owner for 26 years) Roe

Bruce, Tamuiel's issue was the ground switch which kills the blower until the metal temp reaches a certain value. I never caught it here but we did a lot of research when I saw he posted it elsewhere. The later GM parts books were wrong and the naming convention was different from all other years in the parts book I found bit we sorted it out. It was the aluminum temp sensor just to the right of the thermostat housing. I'll add a photo of the proper sensor for 1979 if I can find the capture I saved. It looks like there is a near identical sensor but with different threads. I suspect the different threads were due to the aluminum intake in 1979. The other PN seems to have fine threads and may have been an issue tapping in cast aluminum  (just a guess).

Scott

bcroe

Quote from: 79 Eldorado
I was really curious as to what the system looked like. You will never believe it but someone in the Netherlands has a complete system, and yes I mean complete even down to the sun visor with a sticker showing the Tripmaster information on it, on eBay for sale currently. I'm really glad my car did NOT have the system because I'm sure I would feel the urge to repair it but what an interesting piece of technology. I'll post the photos I saved as I suspect the person selling on eBay wouldn't mind as we are likely their target market!

Bruce, Tamuiel's issue was the ground switch which kills the blower until the metal temp reaches a certain value. I never caught it here but we did a lot of research when I saw he posted it elsewhere. The later GM parts books were wrong and the naming convention was different from all other years in the parts book I found bit we sorted it out. It was the aluminum temp sensor just to the right of the thermostat housing. I'll add a photo of the proper sensor for 1979 if I can find the capture I saved. It looks like there is a near identical sensor but with different threads. I suspect the different threads were due to the aluminum intake in 1979. The other PN seems to have fine threads and may have been an issue tapping in cast aluminum  (just a guess).  Scott.

So actually the temp switch went open circuit?  I would never have noticed,
first thing I do (starting with my first Toronado) is short out that switch, I,
and not the car will decide when to run the blower.  My aluminum intake
is also gone, put in a 76.  Good to put in my fix before anything else fails. 

The problem with that evilbay item, is it probably uses a custom processor
chip, which at this age has failed, no replacements possible.  Had that issue
with a ZEMCO and a few other things.  The 70s EFI did not use much
custom, which is why they are repairable.  Bruce Roe

TJ Hopland

That was a fun video and an interesting system.  Took a fair amount of input for not a lot of output but I guess for the time period it was something.  I'm not sure how useful it would have been but sure was neat and not very likely you knew anyone else that had one.     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason