Rick Olson

Hi All,
I just purchased an '03 F150 XLT fx4 at an auction for very little money. Said in the description that it runs rough, will not idle without keeping foot on throttle.

I just got it home and am trying to figure out if the engine has something relatively simple going on or so major that I should just replace it.

When I start the engine I have to hold the pedal down to get it running and keep it running. Minimum rpms is about 1200-1500 or it will stall.

When it starts there is a big cloud of blue smoke, but the exhaust mostly clears up. If I let up on the throttle and press it again I get another cloud of blue smoke and then it clears up.

All the while the engine is vibrating and shaking a lot.

Oil level was and is just below the max fill mark and oil is fairly clean and not milky.
Coolant is full and clean as well.

Forgot to mention that it has 140,xxx miles on it. I have not read any codes yet as I can't find my OBD reader at the moment but will try again tomorrow.

Anybody have any thoughts on this based on the symptoms I'm describing?

I will attempt to get more specific diagnostic data tomorrow and post it if I'm successful.

Thanks,
Rick

white89gt

If I had to take a stab at it, I'd say you've got an EGR problem.

rcairbear

X2 with White, also check for vacuum leaks.

Rick Olson

Thanks for the input.
I cannot locate my ScanGuage tool so I went to AZone and bought one of the cheap $50 readers. I read the short directions. plugged it in with the key off. turned the key to "on" and nothing happened. Screen is completely blank. I'm going to try it on my Montana after work to see if its the reader or a problem with my OBD socket on the truck. Ugh.

white89gt

Sometimes you can tell if it is EGR by pulling the vacuum line (and plugging it) to see if it evens out. Just depends on what exactly the issue it.

rcairbear

Another thought- check your pcv valve and tubing system.

Aragorn

Check the above but you also may need to look at the IAC. It's on the back of the throttle body which is a pain to get to. Most likely it's a combo problem so eliminate one at a time.

Rick Olson

Okay Guys here's an update.
Started going through the EGR system and found out that everything works as it is supposed to, HOWEVER, in removing the throttle body so that I could verify that the passage from the EGR valve was clear, I found a large vacuum line elbow was off and resting up against the firewall. I know that I didn't bump it or knock it off as the manifold port that it was supposed to be on was covered in dust, not clean.

After verifying that the vacuum elbow was not torn or damaged I pushed it back on the manifold and re-assembled everything with hopes that I had found the source of the rough idle and stalling. While it does run better, it does not run smoothly. I can idle at about 800 rpms, but it it's still rough.

I did replace the pcv valve, but the old one was operable and it made no difference.

As to the OBD II not reading, I checked the # 16 pin and #4 pin and had zero volts. After checking the manual for the fuse diagram I discovered the fuse for the cigarette lighter and data link was blown. Replaced the 20 amp fuse and Voila! 12 volts on #16 pin and grounded to #4.

Plugged in the reader, turned the key to "on" and.......0 dtc on the readout. Ugh!

Still thinking that I might have issues with either COPs or plugs, I started looking them over. #3, #5, and #8 are aftermarket COPs. I also noticed that #7 is not bolted down tightly. I have read elsewhere on this forum that it is a PITA to get that one tight. I guess the PO gave up on it. It is very loose and the COP moves up and down freely by hand. Maybe it's not making contact with the plug? Ran out of daylight to find out tonight.

This truck is 14 years old, and has just over 140K on it. I think I will just order the new plugs and COPs and change them all.

Gnite.

Past my bedtime.
Rick

OhioLariat

Looks like you're headed the right direction to me. You fixed a vacuum leak, eliminated the EGR as culprit, and are headed toward plugs and coils (which should probably done anyway not knowing the history). When you checked the PCV, did you look closely at the entire tube assembly? They're known for developing cracks as well.

Good luck!

P.S. Only Motorcraft plugs and COPS are recommended (although I've read folks have good results with Denso coils, too.)

Aragorn

If you do go for all the plugs and coils I found it easier after I pulled the fuel rails. I also had the manifold off which helped a lot but no need to go that far. Before that I couldn't get 4, 7, or 8 out. I'd check plugs 1 or 5 on the front as they are easy to get to and can give you an idea how the engine is running.

I'd also suggest buying something like a BAFX wireless/bluetooth scanner and using something like forscan or torque pro to get some engine stats. I use my laptop and let it run while driving and can see the entire run which is nice.

Have you tried cleaning the MAF at all? While I've never seen any improvement with it that may be a shot as well. Make sure you get MAF electronic cleaner for it. What's your air filter look like?

Here is a good chart