I have a 93 flareside 5.0 auto ext cab 2wd w 198000. Ford racing headers, under drive pulleys. My problem is a random rough run/idle while in drive. Loss of power and knock sporadically while in drive. New rear fuel pump,used to take care of problem on the highway. Sometimes runs great, other random times runs horrible while in drive, if shifted to nutreul it's fine. Replaced cap and plugs, need help guys. FYI p.o. Has oxygen sensors plugged, but have owned truck for two years and never been a problem, also leaks psteering fluid like a civ, needs new gear box. Any suggestions? Thanks in advance.

 

Fix the o2 sensors, clear all the codes, then see where you're at. You wouldn't expect a non computer controlled vehicle to run with intergal parts missing would you? As for the box, try Lucas, for it to work, you really gotta suck the reservoir dry, then replace with just Lucas, has greatly slowed any leak I've ever attempted to cure with it.

 

The o2 sensors tell the vehicle whether the exhaust gasses are too rich or too lean, and allow the engine to determine if it needs to adjust other settings to get the perfect mixture... I'm with Cletus, you definitely want to consider replacing those sensors.

To help us in the diagnosis, can you describe the sound? Is it a ping (would signal the engine is knocking) type sound or is it a shudder (usually a misfire)?

 

What about replacing the rotor and plug wires? They wear out too.

You should have only one O2 sensor.

 

I did replace wires, cap, and button. And I do only see one o2sensor(a dummy one). The previous owner plugged it. It's hard for me to believe that's the problem, since I've driven the truck for two years without this problem. It also seems to happen more in gear, not in nutruel. Could it be a fuel delivery problem?

 

Check your codes, either way, there's volumes of literature and information on how the system works with the required sensors, but nothing on how to pick and choose which ones you like, and have it run properly. I would be concerned because with no o2 sensor present it should stay in open loop and run extra rich, so you may have a fuel pressure problem. Check the fuel pressure running both with and without vacuum, also if you have dual tanks, does it do the same thing on both tanks?

 

X2 that is exactly what is going to happen when someone tries to "trick" the computer.

 

Thanks for the info guys! I understand the sensors have their purpose, lol, I'm not the one that took it off. Hopefully I have a temporary solution. I assumed that since he had a dummy o2 sensor, that he had a chip plugged into the sensor that fed a code to the computer....wrong. If the o2 sensor plugs into the passenger side fender area, then I found where it goes. The p.o. Had a paper clip jumping the harness. I guess after two years it got too eroded. I replaced the paper lip and took it for a mile test drive....no problems. I will replace o2 sensor and plug harness this week. I will report back if it does not solve the problem. It's so weird to me, the random things like this on my truck because the p.o. Is a ford dealer mechanic, lol.....scary