93 4.0l

DLog · May 13, 2018

Hey guys I need a little help. I just recently got my ranger running after about 2 years ( lost interest with lack of time to work on it) but wife gave me a deadline to have it out of the garage so here I am. I have a 93 4x4 4.0l 5 spd it fires perfect every time but runs rough (sounds cammed) and smells very rich. at the moment I have no exhaust what so ever on it and the o2 sensors are not hooked up. No CEL at all would the o2 sensors be part of why its not running right or why its running rich? I don't have a y pipe at the moment to install the o2 sensors , the main reason they aren't in.

RonD · May 13, 2018

O2 sensors are not used on Cold start, O2 sensors need to be above 650degF to work, which is why they are heated.
So computer will run the engine based on air:fuel mix tables in its memory, usually for at least 4 or 5 minutes

CEL should be on if O2s are unplugged?
The heater circuit is monitored, and with no voltage passing thru the O2 heater..........it would set a code and turn on CEL, O2 sensor are major sensors.
Does CEL come on with Key ON, it should, if not then bulb is bad or wire is disconnected
CEL bulb gets 12volts with Key ON, computer Grounds it to turn it on.

As for misfires and Rich smell, check coil pack wiring, I mix this up all the time
Coil pack spark plug wires are:
3 4
2 6
1 5
front

Double check the 5 6 4 wires, all the way to 4, 5, 6 cylinders on drivers side, very easy to reverse 2 of them

And how old is the gasoline in the tank?

You don't want to run the engine too long with only exhaust manifolds, when you shut engine down colder air can come in and it could warp exhaust valves, long shot but not 0 shot

DLog · May 14, 2018

RonD said:
O2 sensors are not used on Cold start, O2 sensors need to be above 650degF to work, which is why they are heated.
So computer will run the engine based on air:fuel mix tables in its memory, usually for at least 4 or 5 minutes

CEL should be on if O2s are unplugged?
The heater circuit is monitored, and with no voltage passing thru the O2 heater..........it would set a code and turn on CEL, O2 sensor are major sensors.
Does CEL come on with Key ON, it should, if not then bulb is bad or wire is disconnected
CEL bulb gets 12volts with Key ON, computer Grounds it to turn it on.

As for misfires and Rich smell, check coil pack wiring, I mix this up all the time
Coil pack spark plug wires are:
3 4
2 6
1 5
front

Double check the 5 6 4 wires, all the way to 4, 5, 6 cylinders on drivers side, very easy to reverse 2 of them

And how old is the gasoline in the tank?

You don't want to run the engine too long with only exhaust manifolds, when you shut engine down colder air can come in and it could warp exhaust valves, long shot but not 0 shot

Cel works. I'll double check it when I get home. And I'll plug the o2 sensors in and get the y pipe asap and double check the plug wires. Gas is new. Tank was pulled and cleaned before I started it. I had the truck torn way down trying to get it fixed. There is a couple vacuum line that are plugged off as well I dont know where they go or if they are needed. I'll have to get a pic of that when I get home.

Sent from my SM-G955U using Tapatalk

cp2295 · May 15, 2018

Yeah no manifolds and exhaust system is gonna cause that thing to run rough as hell. I’d hook the exhaust up and get the o2 sensors hooked up and go from there.

Also if the FPR isn’t hooked up to vacuum it’s going to cause excessive pressure at the rail which could cause too much fuel to spray in the cylinders, let us know.

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DLog · May 20, 2018

Sorry guys I got sent out of town for work and just got home to look at the truck. The check engine light does work, plug wires are installed correctly, FPR hose to vacuum is on. Pulled plug wires and made sure all are making good contact one by one. All wires are good. Ordered y pipe gaskets and bolts will install them and try to finish out the rest of the exhaust and see what happens. Thanks for the help so far, would either of you guys have pictures of where exactly the vacuum lines go from the intake?

93 4.0l

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