I have replaced the following on my 300 I-6 after it suddenly started running bad (rough idle, loss of power, poor mileage) a few months ago:
TPS
O2 Sensor
MAP Sensor
Intake Charge Temp Sensor
Coolant Temp Sensor
Knock Sensor
EGR Position Sensor
Cap and Rotor
Fuel Filter

Also, I had the throttle plates cleaned and I cleaned out the Idle Control Valve.

It still doesn't run right. When its cold, it seems to be snappy, responsive, and idles pretty good (except for the occasional sputtering and near dying). When it warms up, the power is down, the idle is rough, and its really sluggish. I have read a bunch of posts and it seems like the Idle Control valve may be bad, I need a new fuel pump, or my injectors are in serious need of cleaning. I need either an exorcist or some advice on what else I should do.. If you have any input on this it would be greatly appreciated..
- Nealio

 

Nealio,
Ive got to ask you ...Why did you replace all those things without confirming they were the cause of your problem ? Regardless of whether an engine is computer controlled or not , always start with the basics . The Idle Air Bypass Valve often times needs cleaning , but this will not affect off idle performance . You didnt mention changing / having a look at the spark plugs ..do that .Check your fuel pressure , it should be 40 to 60 Psi at idle . Check that the Egr valve operates properly . Have a look at the air filter , pcv filter and valve . Id rather you isolate the problem and symptoms before you just change parts hoping that will fix it ...Lots of us here that have experience that can help you .
Paul

 

Once again, Paul is right. KTMNealio: learn how to run an engine self-test so your truck's diagnostics system can tell you what may be wrong.
A Chiltons or Haynes manual is a good place to start, as are these internet sites:
http://www.dalidesign.com/hbook/eectest.html
http://www.westecauto.com (go to forums, then Ford, then how to retrieve codes)
With nothing more than a simple piece of wire, you can get your truck's computer to output a system diagnosis through the check engine light on the dash. Its coded info, but its not hard to learn how to read/interpret the codes. Keep posting and we'll help you anyway we can.

 

I guess I should have stated more in my post. I had it scanned and nearly all of the items I replaced failed on the scan (well, I've had it scanned 4 different times so far and new stuff keeps showing up). The EGR position sensor did not show up as failing, but when I tested the resistance through the sesor's movement, it was irratic. I ran the self test and it flashed out about 20 codes the last time I worked on it. The fuel pressure and vacuum were supposedly "fine" the last time I took it to a garage. The reason why I think it was a sensor is that it was running great, (22mpg highway, good power) and then it just started running like it does now. Every time I replace a sensor I notice a slight improvement, but not huge one. I will pull the plugs tonight and look at them. As far as the EGR valve, how do I check to see if its operating properly?
(oh yeah, I have a Haynes manual as well)
Thanks,
- Nealio (aka Aaron K. Neal)

 

Neal ,
If you got 20 codes all at once , there is something else going on besides the sensors failing . I could see one or 2 dying , but all of them you mentioned suggests a common thread . I would begin by checking to make sure all the engine and computer grounds are Ok . Have you installed any aftermarket electrical components IE : Fog Lights , Stereos Etc ? You can use a hand held vacuum pump to check that the egr valve moves properly , that it isnt sticking or binding . Also during the engine running self test the egr is actuated , you can always tee in a vacuum gauge and verify visually on the gauge the egr is functioning . Before you do much else , verify that all the grounds are tight and corrosion free .If you live in an area where a lot of road salt is used in winter its easy for grounds to become corroded .
Paul

 

I haven't installed any aftermarket stuff, except I had a new stereo put in when I bought it 5 mo. ago. I am quite confused with my truck's behavior too.. I will check the grounds tonight. It seems to be heat/time related. It runs great cold, not so great warm, and on long trips it runs really poor. Last weekend, I took a drive in the mountains and I just idled around in 1st or second gear. When I needed some juice, it was quite responsive. However, when I got on the highway home, it was acting like it usually does. Sorry I keep adding to the description. I'm just trying to get some ideas on what to look at next, becuase I'm running out ideas myself..
I appreciate the help..
- Nealio

 

Does anyone agree that it is possible that the pcm might be faulty.That could be a cause of all the codes coming at one time also.You might get a dealer to check it or just pick up another at the Graveyard.It costs some but at least it wouldnt be that...I HOPE you saved all the old stuff you pulled off and replaced.Its nice to have spare stuff just in case.....Bill aka wrussis

 

It is possible the Ecu is dead / Dying ? However , if it is the problem , he should not have got Code 11 on the initial KOEO test ...and I assume he got that code during the KOEO Portion of the test . Plus he says the engine runs pretty well cold . I have a theory given all the work done on the truck ....Neal , has the timing been checked ? Was the distributor even moved ? If the timing has been checked , ensure that the SPOUT connector plug was reinstalled . If that plug is left out , the engine cannot change its timing . Which in turn keeps the Ecu from from recieving and data from the sensors which may account for all the codes you got .You say you were in the mountains ...approx what altitude are you talking about ? Rocky mountain mountains , above 6000 ft ? Check the vacuum port that the MAP Sensor uses for blockage and the MAP Sensor hose . Just a theory , hard to make an accurate assesment w/o seeing the truck .
Paul
Paul

 

OK, so I ran the KOEO test last night on my rig again, but this time I noticed it said to make sure the engine was up to "operating temperature". OOps. That's why I got so many codes last time. As luck would have it the *NEW* EGR position sensor is bad and the old one was fine. So much for preventive maintenance. I guess I have a $17 paperweight. I don't think NAPA will take it back. I got "11" "111" codes after I switched back to the old EGR Pos. Sensor. Now I'm back to where I was before: It idles rough and flutters off-idle. I will open a new thread to discuss this..
- Nealio