Does an 87 4.2 6 cylinder yj need an ecu to operate? - Jeep Wrangler Forum

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Old 08-21-2012, 05:41 AM   #1
Join Date: Aug 2012
Location: West Michigan
Posts: 7
Does an 87 4.2 6 cylinder yj need an ecu to operate?

I am quite new to large scale projects such as I have now. The jeep currently has no wiring harness or ecu. If I make the connections for power to the distributor and starter, and connect the ignition, will it run without major issues? A friend says it would be fine since it has a carb on it rather than fuel injected, but I would like some other opinions before I put in the time to do this. After that I would like at least the speedometer, fuel, and the temperature gauges to work as well. Would that all work or do I need to find an ecu and harness for that? For now my goal is just to put it on the road through the winter, save up some cash, and do it right top to bottom next spring.

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Old 08-21-2012, 06:40 AM   #2
90DesertTanYJ's Avatar
Join Date: Jul 2012
Location: JAX, FL
Posts: 635
Bo the 258 will run just fine without the ECU but you still have a few circuits to worry about like lights, wipers etc. The ECU mainly governed EPA stuff like carb settings, dizzy advance and the information from sensors to make your YJ run a cleanly as possible. If a carbed engine is tuned properly it should be pretty clean anyway so go ahead and get rid of it if your in a locale where this is possible. I am in the process of doing this now as I have a Weber carb and no EGR or O2 sensor. I will take the time to peel all the extra wires out soon and eliminate the ECU completely.

Someone else will give you more details as this has been documented here, Search around a little in the mean time and you may find what you need. Painless makes wiring harnesses to rewire your whole YJ. Easy but kinda pricey as well.

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Old 08-21-2012, 06:54 AM   #3
Join Date: Aug 2012
Location: West Michigan
Posts: 7
Thanks very much for the quick reply. I don't mind running the various wires for lights and whatnot. Just wanted to be sure I could have a basic functioning ride to get me through the winter season. I may look into that harness for the spring though. Thanks again!
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