well heres the deal..i have searched and found some ideas...as you can see its 3am here where i am and i have been reading since 11pm....its killing me....well here i go

I went on a nice drive to my parents house which is about 450 miles away..while i was jamming to my music, i noticed my fuel light came on...i was like wait a minute...i only went 280 miles...i usually go 320-350 miles per tank. I changed my spark plugs, tranny filter, and air cleaner before this trip. I reset my computer and the truck idled rough in park and while in drive while stopped. It even stalled on me pulling into a parking spot. I am lost on ideas...maybe the best men on the web could help to shine some new light to this subject...

 

If you felt a slight or even greater loss of power, then I'd guess that you are not running on all cyclinders. I'd guess that one ore more of your coil to plug rubber pieces is not making good electrical contact.

One way you can possibly tell is to look at you cat after a short drive. The gas that should have been combusted in the cyclinder will probably end up being burtn there. If its orange, I'm right for sure (I had a 86 Toyota Cressida that did this to me. It had the same deep well plug design the triton does. Seems so stupid to me....)

 

ok..i should have explained it better...it rough to me is it will be running at 700rpms then drop too 400rpms almost stall then come back up....so its running on all cyclinders...i know that...when i am getting on it...it works like a champ..just at idle and when sitting at a stop light....this truck is starting to act like a woman...Pain In The A**

O yes...it smells like it is running rich....if only i had a spark plug drilled in the tail pipe i could have some flames

 

Maybe one of your O2 sensors has gone to poop. Also, make sure you didn't accidentally knock off any vacuum lines while working on your truck. Good Luck

 

I would definitely check the O2 sensors.

 

You reset the computer? Did you have a scanner or did you disconnect the battery? If you did the battery thing it will take a while for the computer relearn it's stuff It will run on default for a while and I'm not sure if that's good for gas milage.

 

I did the battery and its been well over 1000 miles..usually everyone says a good tank on the highway...i am going to clean the intake this weekend since i have read high mileage trucks have had the ports clogged

also..i had the computer read..no codes...but it was the autozone one..is there a way to ohm the O2 Sensors?

 

You can read the resistance of the O2 sensors but it’s not a real good way to see if they are operating correctly. You need to know if they are operating at “temperature” and you likely to burn yourself messing with them.

If the forward O2 sensors are not operating correctly then your truck is running in “open loop” it thinks it is cold and thus the reason it may smell “rich” Until the computer gets the input that the O2 sensors are to temp it doesn’t pay any attention to the oxygen level in the exhaust because it “thinks” the truck still needs to warm up.

You didn’t mention miles, so if you’re around 50,000 or more it’s a good time to change the “forward” O2 sensors anyway as a maintenance item. Also when’s the last time you changed the fuel filter? Should be changed every 15,000 miles.

You would think if the O2 sensors were bad it would throw a code, but who knows sometimes. You say you reset the computer, why did you do that? Was there a “Service Engine” light enabled? If so that may have been the reason and if you reset it before going to AutoZone the code would have most likely been gone.

It may come back and if so then take it to AutoZone with the “Service Engine” light on so they can pull the code. Good luck…

 

i reset the computer b/c i put new spark plugs and tranny filter in her. I also put a new air filter on it..the old one was really bad. I have just went over the 92,000 mile mark...and i was thinking of changing the O2S's anyways since i have owned the truck since 32,000 miles. I thought about changing the fuel filter last spring but someone told me that any more than 10 yrs old is point less. I thought that was odd..i change pcv valve aleast once a year. Belt every 2 yrs...oil changes within 100 miles of being due...tranny filter ever 10,000-15,0000...i have been pretty **** about alot of things for it..but thats me...i am planning on cleaning the TB intake here soon..i heard those get bad with high miles...thanks for your guys help...makes a difference!

 

Try replacing the fuel filter.

 

Ok, here is another very possible item, the IAC (Idle Air Control) valve.

The minimum idle speed is pre-set at the factory and is not adjustable under normal circumstances. If the idle fluctuates, stalls, idles high or speeds out of control, You could have a damaged or malfunctioning IAC valve.

Idle problems usually involve possible air leaks, fuel injector problems, malfunctioning TPS, PCM problems, etc it is usually best to have the IAC valve and system diagnosed by a dealer service department or someone else familiar with the system.

As you can see the things mentioned in this thread are possible, O2 sensors not working properly, fuel filter etc. but the IAC could be the most possible item causing you the problem.

I will get my Haynes Repair Manual and post what they have to say about it and possible checks. This may take a while but I will post again once I get something written up on it for you, and others as well…

 

I second the IAC problem,,, that is a common problem for mustang's with the 4.6... (Mine use to do that all the time, but was only annoying when cold)

 

This is a little long but I took it out of the Haynes Manual (97 – 99) which is actually good for up to 03’s.

1. The Idle Air Control (IAC) valve controls the amount of air that bypasses the throttle valve, which controls the engine idle speed. This output actuator is mounted on the throttle body and is controlled by voltage pulses sent from the PCM. The IAC valve within the body moves in or out, allowing more or less intake air into the system. To increase idle speed, the PCM extends the IAC valve from the seat and allows more air to bypass the throttle bore. To decrease idle speed, the PCM retracts the IAC valve towards the seat, reducing the air flow. (Possibly the reason you smell fuel because with less air the motor is running rich, if running rich worse fuel mileage)

2. To check the system, first check for the voltage signal from the PCM. Turn the ignition key ON (engine not running) and with a voltmeter, probe the wires of the IAC valve electrical connector (harness side). It should be approximately 10.5 to 12.5 volts. This indicates that the IAC valve is receiving the proper signal from the PCM.

3. If the IAC valve is receiving proper voltage, check the condition of the valve itself. Measure the resistance across the terminals of the IAC valve. There should be 6.0 to 13 ohms. If the resistance is incorrect, replace the IAC valve.

4. Check the IAC valve for an internal short circuit. Measure resistance from either terminal to the IAC body. There should be 10,000 ohms or greater If less the internal circuitry is grounding against the case, replace the IAC valve.

5. Next, remove the valve and check the pintle for excessive carbon deposits. If necessary, clean it with a soft rag. Also clean the valve housing to remove any deposits.


So basically this sounds like the steps a little simpler:

1. Unplug the harness connected to the IAC.

2. Turn the ignition switch to the ON position without the engine running.

3. Measure the voltage present at the harness itself, not the IAC valve but the harness to see if you have 10.5 to 13vdc.

4. If voltage is good then turn off the ignition switch.

5. Now measure the resistance of the IAC valve itself to see if there is 6.0 to 13 ohms.

6. If that is good then measure to insure the IAC circuit is not shorting out to case. Measuring for ohms (resistance) measure from your meters probes to “one” contact (either one) on the IAC valve and one probe to the housing or casing itself of the IAC valve. If it is less then 10,000 ohms replace it.

If you find a lot of carbon build up then it will most likely measure less then 10,000 ohms to the case. You could clean it and that may fix it. Personally if it is that dirty and unless you can get it spotless I would just replace it or you may find yourself cleaning it again soon.

 

OK boys..here we go..I couldnt get a ohm reading for the one that reads 10,000. It never moved..i must be doing something wrong...but i decide to take the whole elbow from the TB off and see how bad it is....all i have to say is OMFG both ports to the EGR valve totally blocked off with carbon build up. The farthest port was build up outside the port...nice ball of poop. I still have it all apart..that back hose is dry rotted...like everyone has been saying...this will be fun putting back together..hehe

 

Have you tried this...put it all back together, clean everything up real nice and then trade it in for a F350 w/ Powerstroke and a warranty and let the dealer worry about any further problems!
Hey, it works for me when I start having car problems...just an idea!