HELP!!! bucking, misfire, no power..you name it

[dbdavis]

Ok folks...I have a problem that i am having severe trouble locating. I have read and re-read a lot of the posts on here and did some trouble shooting myself only to no avail...heres the background info..
Bought a 5.4 '01 eddie bauer with 190k (couldn't beat the price). Ran great when I bought it, but a couple days later is when the excitement started (go figure).
Was throwing the mysterious P0171 and P0174 codes regarding the lean issue in both banks. It stumbles when I take off and then levels out up until around 40-50 mph and it starts bucking/stumbling again. It does not idle rough and sits at around 1200 RPM when idling. Here is what I have tried so far:
Replaced MAF sensor
Replaced Fuel Filter
Replaced PCV connector tube (the one that everyone says cracks in the elbows)-I replaced the entire thing, not just the fitting.
I have checked the vacuum lines for leaks (used B-12) and could not locate anything (I am contemplating paying a mechanic to do this for me again in case I missed something).
I began changing out the plugs today and got 1-3 done (in case of misfire on an unknown cylinder), but I couldn't quite get to the plug in cylinder 4. The COPs didn't appear to have any damage/wear to cause a misfire, but I'm new to those and don't have a tester to verify. I plan on completing the plug swap on saturday. If anyone has any input on the best way to attack the plugs on 5-8 please let me know...looks awful tight on the driver side without taking half of that side of the engine apart.

Drove the truck for about 45 min total, and no SES light. Hooked up the OBD and showed no codes and nothing pending.

The engine still bucks/stumbles when i accellerate, and seems to be worse when going up hill or in tow. I'm also concerned that this may affect my cats, not to mention the god awful gas mileage right now.

Sorry to be so long winded, but any input is greatly appreciated!!

 

[toms89]

I would check fuel pressure and go from there....

 

[F1vel66a]

If fuel pressure checks out take a look at you're injectors make sure they are within specs. Can't remember the numbers off hand but i'm sure you could search the forums.

Also did you replace all the pcv on driver side? There is a elbow in the back of the throttle body that well essentially melt in the center.

 

[Swetrid]

You probably have a bad coil. If you have access to a good scan tool you can access mode 6 data and see which cylinder is misfiring even if the check engine light isn't on.

 

[Erich Zeppelin]

I had the problem, it is a coil misfire. Go to Summit, get the MSD Ford blaster coils and change them all.

 

[toms89]

I would agree that by reading the title of your thread is sounds exactly like a misfire to a T. It also sounds like symptoms of misfire due to clogged cats depending on how you read it but I would all but eliminate this possibility because it is so rare.

What has me concerned is you stated in your post you got a lean code for both banks 1 & 2. This suggest vacuum leak or leak between mass air and throttle body but you stated you checked your vacuum lines, etc.. so I recommended checking fuel pressure to check the status of your fuel pump. Misfire will cause lean reading in offending bank but to do so in both banks suggest more than one.

Faulty cops can obviously cause misfire but there are other potential sources. Ignition wise you have fouled or faulty plugs, excessive plug gap due to age, moisture in plug well, bad boots and cops themselves. Misfire can also be fuel or mechanical related.

Its not a bad idea to replace cops and plugs as these could be considered tune up items anyways and if the misfire is ignition related your set.

I would not suggest replacing other parts, other than basic tune up items, without proper testing and diagnosis. It's a process of testing and eliminating potential sources. Simply replacing parts is a gamble. You may get lucky you may not.

You did not happen to wash the engine after you purchased it did you??
Does it look like the previous owner may have recently??

 

[nobleynobe]

I'm having the same problem on my 98 expedition. Took a road trip and drove about 120 miles with the air on. Had no problems there and back. Later the next day I started to experience this problem. When I accelerate it feels like it's dragging or not getting a full throttle intermittently. I'm not sure the last time it had a tune up because I just bought it used a month ago. Do you think a tune up would help? I see a few suggestions like the last one above me, how much do you think I'm looking at. I love the truck and want to make sure it does me good. Also, I've had to add anti freeze twice already, both times the gauges were reading hot. I think I may have a slow leak from somewhere. Could this be part of the problem? Any help is appreciated. Thank you

Sent from my SPH-L710 using Tapatalk 2

 

[nobleynobe]

Update,
Took it the my dealer. He said I had a bad cylinder coil and it was replaced but it's still dragging, bucking, or stuttering when I accelerate. Wtf. Any ideas? Someone help

Sent from my SPH-L710 using Tapatalk 2

 

[toms89]

I'm having the same problem on my 98 expedition. Took a road trip and drove about 120 miles with the air on. Had no problems there and back. Later the next day I started to experience this problem. When I accelerate it feels like it's dragging or not getting a full throttle intermittently. I'm not sure the last time it had a tune up because I just bought it used a month ago. Do you think a tune up would help? I see a few suggestions like the last one above me, how much do you think I'm looking at. I love the truck and want to make sure it does me good. Also, I've had to add anti freeze twice already, both times the gauges were reading hot. I think I may have a slow leak from somewhere. Could this be part of the problem? Any help is appreciated. Thank you

Sent from my SPH-L710 using Tapatalk 2

You may be leaking antifreeze from the lines leading to the heater core near the firewall. This can leak onto the rear most cops on the passenger side creating misfires.

Or possibly a leaky intake or head gasket. Any signs of coolant on the ground? Steam from the exhaust?

Yes I would recommend tuneup! If it takes care of your issue great. You may identify leaky heater core hoses changing plugs if it is the case. It can also indicate the overall condition of you motor by checking your old sparkplugs. Steamed clean plug may indicate leaky intake or head gasket.

 

[1ATony]

You may want to take a look at your throttle position sensor, if it has gone bad you would experience many of the symptoms that you're describing.

Here's a link to them on our website for your Ford Expedition. Hope this helps you out.

Ford Expedition Throttle Position Sensor TPS

 

[FordandPolaris]

I would second tom's theory. Stick a rolled up piece of paper down the plug holes in the way back on the passenger side. If it comes back green then you have coolant leaking onto the plug. That would ground it to the block causing the misfire.

If you have added coolant twice in a month I would say you have more than a slow leak...

 

[nobleynobe]

So I took my expedition to the dealer and told them everything you guys told me. They found a small leak from the radiator and fixed that. They replaced a coil for the #1 cylinder and changed a spark plug as well. After 2 replaced coils, fixing a radiator leak, and replacing a spark plug I'm having no more bucking. Thanks guys. I wish I could determine exactly what it was but I'm willing to bet that the radiator fluid was leaking onto the spark plug theory. Idk but you guys are the best. Thanks again

Sent from my SPH-L710 using Tapatalk 2

 

[2000_EXPO]

I have a 2000 had the same problems. Check the intake gasket and also o2 sensors. Mine was a mixture of my bank 2 sensor 1 o2 sensor was out and I had a miss on cylinder 6 and was just pulling a code for random miss but that was the only COP that hadn't been changed so that's what I did. Bangs like a champ.

 

[ExpoGoddess]

Yep its an ignition coil pack.... have had that problem with mine also its quite expensive to replace all 8 so Ive done 1 at a time but its a pain in the a$$ Ive done about 6 total in the 10 yrs ive had my truck