Going to try to post important details to help figure out the problem. I'm the 2nd owner of a 2000 ranger 2 wheel drive with the 4 cylinder motor that has 8 spark plugs. I got it about 5 years ago at 87k miles. After few months driving the check engine light comes on and code is something about EGR valve. Dad and I replaced the EGR valve but the light comes back even though the motor seems to be fine. I know its wrong but I've been driving it to this day with the light on up to 140k. In that time I change the oil at least 4 times a year, replaced rotors, replaced pads, replaced alternator, and replaced battery. But the original owner put new belts, hoses, tires and other ware/tare items on it only a few months before it was put up for sale by his son since the dad couldn't drive anymore.

The only issue in that time was maybe 1-2 times a year I would go to start it and it would run rough but after barely touching the gas it would clear out and stop after a couple minutes of driving. No big deal since it would only happen once or twice a year if that but check engine light is on which I know is wrong.

Well in the past couple months its been doing the rough idle after startup more and more. This past week it would do it every time I would head home from work. If I let go of the gas pedal after I start it will die. Just have to barely push it to keep it running. After I drive it a couple minutes it will run without me having to touch the pedal but it runs rougher that it used to like its barely above the point where it will die. So I started looking online about EGR system issues and came across this trouble shooting guide:

Part 1 -How to Test the Ford EGR Valve and DPFE Sensor.

I need to borrow a vacuum tool with pressure gauge with gauge and use it to test the EGR first but I tested the DPFE sensor. With the key on I get the 5v from the plug but when its plugged into the sensor I only get .2volts. Follow the guide and with it started it still shows .2 volts. I put tubing over the top of the EGR valve and with my girl friend barely pressing the pedal to get a normal idle . I breathe in the the tube slightly to create the vacuum and the motor starts to stall and the voltage at the sensor doesn't go up. So I figure the DPFE sensor is bad because the guide and videos shows the voltage goes up if you create a vacuum on top of the EGR valve. Buy a new one at autozone and it still the same.

I guess I need to get the exact code that is tripping the check engine light and I need to borrow a vacuum tool with pressure gauge to test the EGR valve first. Also should see if voltage goes up with the new DPFE sensor. Haven't looked at the idle adjustment because it would feel like I'm fixing the symptom and not the problem unless its common for the idle to loosen up allowing it drop over time.

I want it to run right and get the check engine light resolved. Any help or guidance is much appreciated.

 

If you've replaced the EGR already, maybe this check engine light is an unrelated issue? Have you tried re-scanning to confirm the code?

 

After replacing the EGR valve the light came back on with the same code involving EGR. I'll go to autozone tomorrow and get the exact code and try to use/borrow lone-a-tool one of the their vacuum tool with pressure gauge. Then verify the EGR is working as it should then try to read voltages on the DPFE while applying vacuum pressure to the top of the EGR. Haven't touched the EGR Vacuum Solenoid yet.

 

You can, and I have, blocked off the egr entirely with a metal plate, and by removing the vacuum hose on top of the unit. Then run to store and have them manually remove the code. Imo egr is stupid and will end up doing more harm than good in the long run. They always have issues....why keep them

 

Today I tested the new DPFE sensor and the new one actually reads 1v instead of .2v like the old one when the key is on. Didn't apply a vacuum to the EGR while it was running to see if the voltage goes up but it runs a lot better after that. Acceleration is lot smoother now. But the idle is still way too low and barely runs the first 2 minutes its running until it warms up. But after it warms up and when I'm sitting at lights the idle is low where the truck slightly vibrates/rumbles but if I barely press the pedal its perfect. The vibration at idle is now half of what it used to be. When off the pedal I sometimes can't hear it run since its barely running even with windows down. I think the low idle with vibration is something that just has slowly gotten worse over time.

So today replaced the fuel filter which I never done. Then noticed it was time so put new oil, new oil filter, new air fliter, but still the same low idle problem. Then I noticed that at stop lights I would let go of the pedal and the truck would sit still or take 5-10 seconds before it would move but even then it was slow. I know it didn't use to be like that since I could never take my foot of the pedal without going 4-5 feet quickly. Also noticed in the garage when it would be running at the low idle the interior lights would get significantly brighter after I barely press the pedal to get it to the normal sounding idle. This tells me that is just on the verge of barely running so alternator isn't putting out as much since its not spinning as fast and the fact it sits still when in drive tells me its not at the idle rpm it used to be. I need to wire up a tach which I've never done and cluesless on. I do have a new tach somewhere that I wanted to add to the truck but never did. But thinking about figuring that one out to give myself more data.

So I take the cover off to get to the arm that moves when you press the pedal. I adjust the bolt that sets the idle when the arm stops with the pedal released. I increase the idle maybe 1/3 of a turn and now it idles like it use to and sounds fine. What caused it to drop originally no idea. Maybe its loosing compression since its at 140k now and just needs idle set higher?!?!?!?!?

Also I disconnected the battery when I replaced the fuel filter and I'll get autozone to read the fault code if check engine light comes back on. Crossing my fingers that it doesn't or if it does that it'll take a while.