High Altitude CJ5

[Ogletr56b]

There is supposedly a Black/ White wire with an eyelet floating around the passenger side of my 83 CJ5 with the Electronic stepper version of the Carter BBD to act as a high altitude jumper. I can't find it. Can someone tell me where the source of the wire is? I know it is supposed to be on the passenger side next to the tach sender, but it is not there on my truck. What is the source, and can someone verify if it is actually black with a white line? I have spend hours. I'm in the mountains at 13k ft and I cant go over 1/4 throttle without it puking on itself. I have no power, I'm slowly overheating after about an hour on the highway at this altitude, and get about 8 mpg. When my altitude goes under 3k, its fine again. It is especially miserable when the car is cold. This carb is driving me crazy, but it is only about 3 months old.

 

[Torxhead]

I had one on my '86, that was located near the ignition coil. It was a small gauge white wire located near the ignition coil, with a ring terminal at the end to be grounded to the head. It was supposed to be used at altitudes above 4000 ft. It leaned out the fuel mixture and advanced the timing. It also required the engine to be off so it would reset at startup. It did work pretty good for high altitude driving.

 

[Hedgehog]

What kind of carb are you running?

You need to fill out the vehicle information so its easier to help you out.

 

[hagar]

Originally it was taped back along the outside of the wiring harness loom in the location you describe. The ring eye terminal would have been visible and it attaches to the bolt on the engine block where other ground wires are attached.
In the meantime, mechanically advance your ignition timing 5 degrees which should improve driveability right away.

Is the factory emissions label still legible on the grille ?

 

[Ogletr56b]

Thank you for everyone's help. Mine was located in the black plastic loom covering. I hooked it up, but conditions haven't seemed to improve. I will adjust the timing; hopefully that helps. Again, thanks everyone.

 

[Lumpy Grits]

:ww:
You don't want to use the high altitude jumper wire below 4K'(ASL).
OP-Are you still run'n the Carter BBD carb? If so, when was the last time it was rebuilt?
LG

 

[Torxhead]

If you have the "Nutter ByPass" that would change how the altitude compensator works.

 

[Ogletr56b]

I recently purchased the Jeep. I was told by the PO that the carb is new. It still has the NAPA sticker on the side. As far as I can tell, everything is stock, even down to what appears to be Cali emissions package.

 

[Ogletr56b]

If you have the "Nutter ByPass" that would change how the altitude compensator works.

I don't know anything about this mod, but nothing seems to be altered. I will do research on this...

 

[Lumpy Grits]

Nutter bypass how to.......
This is a Picture Guide to Nutter Bypass - JeepForum.com

Is your Jeep a CA. model?
Do you have to pass any SMOG testing in Utah?

LG

 

[Torxhead]

The "Nutter Bypass" will affect the computer control of the distributor and carb. Which also would affect the high altitude computer compensation, Lumpy has posted excellent ways to detect this modification. This modification works great if your computer is shot. Hopefully you will find an unmolested system. I would suggest the "Team Rush Upgrade" for the 258 which can be found in this forum and other locations on the net which is basically changing the distributor cap, rotor, and wires that will not affect any computer operation.

 

[007]

Make sure you have NO vacuum leaks. Cap off your advance and set timing appropriately. Reattach vac advance and then you're going to be able to handle 1deg of additional base advance for every 1000 feet above your base altitude.

Naturally all this depends on how often you're up in the mountains versus how much driving you do at your base level. You don't necessarily need to add 10 deg if you live at 3000, but you can. You could settle for something in the middle or just set it as high as you can handle without knock.

I live at 414' and I run about 10deg advance all the time. But when I go to Colorado I bump it up 10deg to 20.

The other thing you're going to want to look at, is perhaps rejetting the carb. I had to go two sizes smaller in my 2100.

 

[mtnwhlr]

just set it as high as you can handle without knock.

Living in Co. this is how I set the timing on my stuff.

 

[Lumpy Grits]

Good 'old-school' ign timing info here.
timing vs overheating [Archive] - NastyZ28.com

You may well want to try the highest octane rated gas in your area also.
LG

 

[007]

You may well want to try the highest octane rated gas in your area also.

LG

Octane may help it start a bit but it's the lower octane (85 in Colorado) that helps with vapor lock at altitude. Read A LOT about that in anything from Jeep to antique Porsche message boards.





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[Lumpy Grits]

Mine sure starts easier and runs better on the 91 we get here in PRK, no matter what the altitude is. I live at 2700'(ASL) and have been to well over 10K' w/CA. gas in my Jeep.
I believe a lot of it has to do with flash point.
Also, if you run a carb(I do in my Jeep)or FI.
I do agree that at HA. You have lower compression so lower oct fuel makes sense.


LG

 

[Bill D]

The lower octane is better at preventing vapor lock but avoiding ethanol additives is the most help. Sometimes gasoline without the 10% ethanol is hard to find but usually a search will produce positive results.

 

[Lumpy Grits]

We don't have that choice here in PRK.
Why I use prem as it has less 'E' in the mix.
LG