2000 Ranger XLT, 3.0L.
When first starting it it is extremely ragged running, sometimes even setting a code (0304).
Things I've tried include:

• replaced all plugs and wires (VERY necessary),
• visually observed injectors looking for seal leaks that could result in pressure lose,
• ran injector cleaner through tank couple times,
• before starting i let the fuel pump run to pressurize the system (sometimes even two or three times). Sometimes that's enough to get a clean, smooth start; sometimes not.

Regardless, if i increase rpm's it will eventually smooth out within 15 seconds or so.
This seems to have started after I replaced battery in October. Coincidence? Before spending money on a mechanic and paying diagnostic fees i'd like to hear what else y'all think it could be. Thanks much, Jerry

 

Welcome to the forum

Because its not expensive I would change the ECT(engine coolant temp) sensor just on speculation
ECT sensor tells the computer how much Choke to apply based on temperature at startup
Too much Choke can flood a cylinder or two, to little causes not enough vapor to fire
Once the cylinders heat up, 15-30seconds, it can smooth out a bit even with too much or too little Choke

There are TWO temp readers on your engine
ECT sensor, 5 volt, only used by computer, has light green and grey wire
ECT sender, 12 volt, only used by dash board temp gauge, has a red and black wire
So NOT interchangeable, lol.

If starter motor seems to be slower turning on COLD start then might be battery
Easy to test with volt meter

 

thanks Ron, new battery; starter motor not an issue, fires right up.
that ect sensor could also answer another what i thought was an unrelated question.
my engine temp gauge was spiking. I had a mechanic flush the radiator and heater core and replace thermostat. Seemed to fix issue. For a while. Now, if i sit and idle it starts spiking again until i start driving. I was thinking radiator, maybe not. I suggested ect sensor to the mechanic but he said not.
definitely gonna replace ect sensor
thanks, jerry

 

The high temp on gauge is not related to ECT sensor, gauge uses the ECT SENDER, different device

But it reads like the fan clutch might be failing, or water pump impeller

After engine has set for overnight, 6-8 hours, open hood and try to spin the fan blades, should be tight, "locked", hard to spin
Start engine, run it for 20-30 seconds, shut off engine
Spin fan again, should spin easily now, unLocked

The fan clutch has a metal spring on the front that is heated up by radiator heat, as the engine and radiator warm up the spring expands and starts to Lock the fan so it spins closer to water pump RPMs
If the fan is not locking up then when you are driving slowly or stopped not enough air is being pulled thru the radiator so temp starts to go up
When you are driving above say 30MPH, then there is enough air flow from vehicle speed so it cools back down

Water pump impeller blades can get eaten away if you don't change coolant every 2 years, and you get the same symptom, at higher RPMs water pump can keep coolant flowing fast enough, at idle it can't so engine starts to warm up

 

Looking online at one of the local auto parts stores. They are listing ect sensors such as:

MasterPro Ignition 2 Terminal Multi-Purpose Temperature Sensor

Murray Climate Control 2 Terminal Temperature Sensor

Standard Ignition 2 Terminal Coolant Temperature Switch

Standard Ignition 2 Terminal Temperature Sensor

MotorCraft Multi Purpose Temperature Sensor

MotorCraft Water Temperature Switch

any one of these superior to the others? Warranties range from limited lifetime to 1 year. Prices are within $10. No other driver so trying to get what i want on first try. Thanks, jerry

 

checked the fan blade first thing this morning. Drove about a mile and checked again. Blades spun the same, easily, both times. Guessing water pump is in order. Reman pump has 1 year warranty. New one has lmtd lifetime. $20 price difference. Are remans any good?

 

Fan clutch is bad if it spun easy BEFORE starting engine, should be locked

Not water pump

 

After further research ive decided my earlier assessment of the clutch was incorrect. The blade rotates fairly easily by hand, whether cold or hot, but does not spin. Might move about 1/8th of a turn either way

 

Up to you really, I wouldn't but its because I am cheap, I do buy motorcraft parts, which are more expensive, but don't replace parts until I have to

 

Good deal. Thanks much. Jerry

 

Given that the fan clutch seems to be constantly locked and temp gauge goes far up while idling would it be a safe assumption that the pump is not moving enough water at idle rpms to cool the coolant? Thus indicating the need for a new or rebuilt pump?

 

Fan clutch is UN-locked all the time from your description(easy to spin), so when driving slowly or stopped not enough air is being pulled thru the radiator causing temp to go up
When above 30mph fan is not needed so temp goes back down

 

Just to verify - the ect sensor has TWO wires in the connector and the ect sender has ONE wire. Correct?

 

Please reread post #8 where i redescribed the turning effort. I must have been editing it after you read it. Sorry for the confusion

 

Check fan again after engine and radiator is fully warmed up, 15min drive, and let it idle a minute or two so temp climbs up a bit, then turn off engine
Then check fan, it should not "spin", you can move it with your hand but it should stop moving when you release it no matter how hard you try to "spin it", no continued spin at all