Rough idle when cold
 

I have a 1997 ranger 2.3. I recently changed my pcv with a after market brand. When I started the truck, the oil pressure gauge did not move for about three seconds. The vehicle idles rough. After three seconds, the oil pressure gauge moves to it normal position, but the idle is still rough. After the truck is warmed up, the rough idle goes away. There is also a small backfire sound for a few minutes as well. I replaced the pcv valve with a ford brand. The problem is still there.

I have changed the plugs, wires, and coil. There is no change in the rough ideal. Any ideas?

Welcome to the forum.

Oil pressure needs to be above 6psi for oil pressure gauge to work, so rough running may have pressure below that, unless you hear valve train noise you have pressure, so no worries there.

Nothing specific comes to mind for the roughness.

On the 2.3l only the exhaust side spark plugs and coil pack work when starting the engine.
With engine cold unplug 1 spark plug on exhaust side and start engine.
repeat for each spark plug on exhaust side
see if you can tell which cylinder isn't working at start up, i.e. roughness is the same as will all spark plugs connected.

When you start a cold engine, idle RPMs need to be higher than warm engine, usually 1,100rpm is minimum.
Does engine do that?
If not then check IAC(idle air control) valve, it will have 2 wires connected, make sure they are connected.

oil pressure
 

I find it odd that the problem developed immediately after I changed my pcv valve. The valve is buried so in my moving of the hose that connects to the valve, could I have broken off the oil pressure sensor wire? If so, would my truck still run without the pressure sensor connected? My other though is that I broke a vacuum hose somewhere under the intake manifold.

Would an idle air control motor cause low oil pressure on start up, rough idle until warmed up and then run fine after a few miles?

Computer doesn't monitor oil pressure in 1997, so it can be disconnected without effecting anything but the gauge

Yes you could have pulled off a vacuum hose, cold engine needs less air and more fuel, vacuum leak gives it more air, so engine would run rough until it warmed up.

To test for vacuum leak wait until engine is warmed up.
Then while engine is idling unplug the IAC valve wires, IAC Valve will close and idle should drop to 500-600rpm or engine may even stall, either is good, it means no vacuum leaks.
If idle stays high, 700 and up, then there is a leak

No change
 

I unplugged the iac valve and there was no change to the idle of the engine. I will look for loose or broken vacuum lines under the manifold when I get Time to take it apart. Could it be possible my iac valve is not working?

I have a 2004 2.3 and when I push the accelarateor it make a rattle noise and goes away when I'm not pushing the accelerator or at high rpms dose anyone have an idea what it could be

Remove IAC valve and then plug in its wires
Turn key on and IAC Valve should open all the way
Unplug the wires, while key is still on, and IAC valve will close
Plug wires back in and it should open again
Repeat a few times to make sure it isn't sticking.

Computer always opens IAC valve all the way for starting, thats why all fuel injected engine should have high RPMs on start up and then RPMs will drop as computer sets idle RPMs for engine temp.
Many don't notice this since they have their foot on the gas pedal.
Try starting engine without touch gas pedal to see if this happens

Welcome to the forum

You should not post your questions in someone else's thread, bad manners, like interrupting someone.

Maybe a moderator will move this to it's own thread, or you could start your own thread......
Here: DOHC - 2.3L Duratec / Mazda L Engines - Ranger-Forums - The Ultimate Ford Ranger Resource

problem solved
 

After several days of dealing with a rough idle in the morning, I replaced the IAC motor this weekend. Problem solved. Thanks for all the help.