I reinstalled 94 4.0L OHV and it has a miss at idle and while on the road. I found an unplugged wire connector where the O2 sensors connect and don't know if or what it connects to. Doe's anyone what the connection is to.

 

Welcome to the forum

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Not alot to go on, picture of connector would help

If you have a manual transmission then there will be an unused connector behind the engine by the firewall, 2 or 3 wire connector, it was for automatic trans use

Recheck firing order on the coil pack and at each cylinder
3 4
2 6
1 5
front

The 5 6 4 side always gets me, either on the coil pack or at the spark plug

 

Yes manual trans. round 2-conductor I believe looks just like O2 sensor connectors but darker in color vs. white on O2's I counted ck engine light codes temp sensor came up was getting voltage to it and resistance across sensor was in range but did not recheck when cold verses hot Thanks for your help it doe's seem to be an unused connector. Will have to look further into this (mildly) rough idle and down the road. I bought this truck for parts and soon realized it was much better overall than my 6- year newer ranger. The heads were cracked and had them redone I found the water jackets around the rear two cylinders backed with stop leak. Don't know any history on the truck but found compression (cold engine) had about 30 lbs. on 2-cylinders 0- on other 4. Truck came with no radiator replaced that with new one buy passed heater afraid it is clogged w/ stop leak. i am certain engine was overheated on more than one occasion radiator hoses felt like jelly.

 

2 wire round would be automatic trans connector so not used with manual trans, usually has a plastic plug in it but it can fall out

O2s after 1985 all use 4 wires, just FYI

Yes, the 4.0l OHV engine heads tended to crack if overheated just once, weak spot between valve seats
And its fine to use sealer as a temp fix
It can clog older rads and heater cores, so they should be flushed
1994 heater cores are cheap and easy to change

 

Thanks again for your help.