Vehicle Info:

Vehicle: 2004 Ford F-150 STX 4x4
Engine: 4.6L Triton V8
Mileage: Appx. 99,000


Symptoms:

Shifting from Drive to Overdrive is almost impossible, especially when
going up a steep hill. It will drive as normal until I try to pass someone or
accelerate up a large hill, at which point the motor begins to miss and
lose power. Attempting to switch over-drive off and get up the hill
doesn't help any. The check engine light doesn't come on at all.

Here's what I've tried:

1) Replaced the Fuel Filter.
2) Checked Catalytic Converter. Good.
3) Checked Fuel-Pump. Good.
4) Replaced Spark-Plugs.
5) Replaced all 8 Coils. (Coil-Over-Plug System)

Still having the same issue.

Any ideas? HELP! I can't afford to trouble shoot much more!

 

Did you check the fuel pressure at the fuel rail?

 

No. The mech who checked the fuel pressure had some difficulty checking it from under the hood, so instead he disconnected the line at the Fuel Filter and pulled it from there. I think it was around 140Lb, something like that.

Are you saying that a problem at, or around the fuel rail could cause this kind of issue?

Thanks for the reply.

 

there should be no problem checking it at the rail.
I'm sure one of the guys that knows more will post
something. it sounds like fuel presure to me.

 

Bump.

 

Google search EGR Valve and read to see if a faulty EGR Valve or DPFE sensor could be the the problem. My truck is doing the same thing and I am going to try to replace the DPFE sensor.

 

Alright, thanks. I glanced at a few websites to try and get a feel of what the DPFE and EGR do, and I think I may have a good understanding now. Only thing is I'm not sure if the symptoms on my truck match what I've found so far on the internet. I will look into the symptoms of a bad DPFE/EGR later this evening when I get home. Right now I'm on lunch break. I am going to buy some MAF Cleaner from the local parts place soon, going to clean that as well.


Does a bad DPFE or EGR throw engine codes? I forgot to mention that I was also pulling a Lean in Bank 1 and Bank 2 code(s). Maybe the MAF Cleaner will knock that out? I'll check for a vacuum leak aswell I guess, though the mech I've taken it to before said he found one and fixed.

Thanks again, any more info would be appreciated.

 

My truck has not thrown a code yet and another board member who told me about the issue said that his took about a week to finally throw a code so maybe that is not your problem, but you never know.

 

Ah, I see. Apparently mine is throwning codes to, as I said I was able to pull the Lean in Bank 1 and Lean in Bank 2 codes, however the check engine light has yet to come on, not even a blinking signal.

My problem's been alive for awile now, actually probably going on over a month with no engine light. /shrug

I just finished cleaning the MAF Sensor aswell, with a can of CRC MAF Sensor Cleaner. I'll post back at around 3PM Central Time with an update, though I'm skeptical about any great results.






UPDATE: Cleaning the Mass Airflow Sensor seemed to help at first, but after a short drive (appx. 10 miles) the problem reared it's ugly head head again. Do I need to disconnect the negative terminal for any length of time? Would it make any diff?

 

Are you positive your PCV elbow hose isn't shot?

 

If I'm looking at the correct hose, the one that runs from near the MAF Sensor, then it appears fine. The line is made up of a plastic material with black/green clips at either end. Where it joins together with the valve covers is really lose though. Is that okay, or should it be really snug at the connection between the end of the hose and the valve cover?

 

No, the one I'm talking about is behind the engine almost up against the firewall.

 

Oh, no but I think I know what you're talking about now. I've seen a few pictures and some similiar threads that talked about the same thing. Can I see it from the topside at all without removing any parts?


:o

 

Bump.

Bump.

 

Anyone else got any ideas?