4.0L Carbureted/Propane powered engine?

[Wow]

I have a '96 XJ that has been parked for over a year now because the CPS and fuel pump are dead along with a few other electrical problems. Now I'm at the point where I need to fix it or get rid of it and I'm pretty attached.

Generally speaking I like old vehicles, my DD is a '73 Chevy, I don't like fuel injection, computers, and crankshaft position sensors. I'm wondering if anybody has managed to remove their computer completely and run an XJ with an AW4 on a carburetor? Doesn't seem like it should be that hard given all the carbed 258s.

On top of that, I'm really interested in converting to propane fuel, right now it's only $2.79/gallon locally vs $3.65 for gas, and it is 100+ octane. I would like to eventually modify the engine with more compression, etc, to take advantage of the high octane. Propane conversions are pretty simple on a carbureted engine, not so much with fuel injection and oxygen sensors.

Basically what I'm wondering is how hard it would be to get a '96 XJ to run without a computer? Has anybody tried that? I do not need to go through any emissions or other inspections where I am.

The major road block I see is getting the ignition to work without the computer and things like the CPS, but, I was thinking this might be a great application for a stand alone distributorless ignition system like this:
http://www.autosportlabs.com/megajolte-p-41.html

Thoughts, anyone? :cheers:

 

[old_man]

Just remember that propane does not have as much energy content per gallon and gets worse gas mileage. I ran propane on farm vehicles for years.

 

[kastein]

I think it'll be easier to make it work with the computer than without. A CPS is a 10 minute job to replace, the fuel pump is a couple hours. Other electrical problems - post em up and see if anyone can answer them... everyone who has posted in this thread so far is a professional electrical engineer.

Propane would be pretty nifty but I'm not sure how you can set up a different ignition setup. Maybe run mechanical advance somehow by making the distributor adjustable, and build a simple point replacement system using something that replaces the cam position sensor?

 

[GrimmJeeper]

putting a carb on there shouldn't be a problem

http://www.youtube.com/watch?v=DTYD-f6fJjM

 

[Wow]

Just remember that propane does not have as much energy content per gallon and gets worse gas mileage. I ran propane on farm vehicles for years.

Right, I've always wanted a propane vehicle but never have for that reason. With the current cost of gas though, propane is still cheaper. Corrected per 100,000 BTU propane is $3.07, gas is $3.17, and diesel is $3.20. Who knows how long that will last...

I think it'll be easier to make it work with the computer than without. A CPS is a 10 minute job to replace, the fuel pump is a couple hours. Other electrical problems - post em up and see if anyone can answer them... everyone who has posted in this thread so far is a professional electrical engineer.

Propane would be pretty nifty but I'm not sure how you can set up a different ignition setup. Maybe run mechanical advance somehow by making the distributor adjustable, and build a simple point replacement system using something that replaces the cam position sensor?

One of the major reasons I like propane is that the engine is simpler, with less to go wrong. No fuel pump, no CPS, no O2 sensor, etc...a lot of things that can leave you stranded. These things have left me DOA on more than one occassion. I know I've seen one of these hooked up to a 258 before:
http://www.autosportlabs.com/megajolte-p-41.html

Does anyone know if it is possible to use the AW4 without the engine computer?

 

[ehall]

The only engine input that jumps to mind for the TCU is the TPS (throttle sensor) which tells the TCU when you are flooring the pedal so dont shift yet or that you are just feathering the pedal so shift sooner for smoother feel. You might be able to fake a TPS signal with a variable resistor mounted to the carb... dunno.

You can eliminate the TCU if you want but you'd have to manually shift.

 

[kastein]

You can run the aw4 with just the TCU under the dash as long as you keep the NSS and TPS wiring, etc. You can also shift it manually (but will be missing second gear) or can build a fairly simple electronic shifter or buy one premade from a few different companies.