Engine miss with no codes showing.

[Heatherin951]

Hi there everyone I am brand new here. I just bought a 2000 Expedition with the 5.4 Triton. I took a chance and bought it at an auction (because the boyfriend can fix anything .
It had a miss and a code for downstream bank 1 o2 sensor. Replaced that and the spark plugs, as well as the fuel filter and air filter. ...Still has a miss but is not throwing a code.
I am guessing its coils. The bf is thinking it may be the EGR as well.
It is a miss that can go unnoticed at start up, but sounds and feels like its on 5 or 6 cylinders as soon as you put your foot on the gas pedal. To say its running rich is putting it mildly.
What do you guys think? I'm waiting for fedex to deliver the coils...and am playing the speculation game hoping so much it will be the fix.
The poor thing had filthy gunky filters, maintenance was not in its life.
Never used seafoam though I've read quite a bit about it the last few days.
I think I may get some for it.

I really like this Expedition. I had an old explorer for years. It was such a trooper. I have an 11yr old son and this expedition will haul him, his friends, and all their "stuff" easily. I love how big and roomy this truck is...and the turning radius is great!

 

[98EXPnSRQ]

I would bore scope the top of the pistons to check for carbon buildup before I put that seafoam stuff through it. I recommend running a tank or 2 of injector cleaner through it. I've had good results with gumout regane high mileage. You will clean the injectors and top end at the same time. As far as your miss goes, I had water under my spark plug boot that caused a miss and it took several days for it to throw a code.

 

[Heatherin951]

Thank You!
I did read here somewhere about the spark plug boot being a possibility. I forgot about that. I will pass it on to the bf.

 

[ExplorerTom]

It's probably not really "mis-firing" as the coil is firing and the computer records it as a successful fire.

Where the spark energy is going might be your problem and what is causing the rough running motor.

Change the spark plugs, coil boots and have a couple genuine Motorcraft coils on hand. When I did mine, i had a similar situation. When I pulled the coils out of the rear plug wells, they were coated in oil. This could be causing wayward spark. I also found a crack in one of the coils (it was on the side). I put in all new coil boots when I put the coils back in- the spring on the inside was wet on most of them. everything seems fine now.

 

[Heatherin951]

Thanks!

Thank You ExplorerTom. Spark plugs were all replaced a few days ago. What is perplexing to me (and I know very little) is that it ran like a dream for about a half hour after the plugs were replaced. Then suddenly was really rough again.
BTW, I paid $1200 for it. It is fairly clean but for some deep scratches the length of the right side and a small dent in rear bumper. Paint and weather stripping is in surprisingly good shape. I had hoped that meant it was garage kept and therefore taken care of...LOL. Silly me.

 

[thenaaks]

Did anyone mention vacuum lines? I had to replace my intake manifold gaskets recently, and had a loose connection right behind the throttle body. Had a bad miss, but no code popped up. There are lots of lines and connections. And some of the rubber hoses get very dry and crumbly.

 

[High Roller]

Take it to Ford ..they can diagnos it for $100.
My truck was running rough...it was the back heater hose leaking and the intake manifold had a crack.

 

[Heatherin951]

It was the coils.

Replaced all 8 plug coils. At least 3 were bad. (Number 7 was great fun to get out btw)
The next day it threw a code for a vacuum line. fixed that and it has been running like a dream ever since.
Incidentally, a day ago we replaced the oil pressure sending unit. The old one worked intermittently and it is a bit freaky having the oil light come on. Felt compelled to check the oil every time!
So the replacement part...faulty. Leaked oil everywhere. But only when it was running at first so it went unnoticed until I was on the concrete at work.
Second one....different manufacturer...also faulty.
Third one, from a different big name parts store...has yet to be installed. Boyfriend was under my expy until 11pm and just had to give it up for the day.
This sending unit is harder to get to than the #7 coil.
This particular parts store sold me 4 bad starters in one day a couple years ago. Should have learned.
Anyone ever have this happen to them?

Also...I love this Expedition more than any other vehicle I've owned. It is the best!

 

[Heatherin951]

My 2000 Expedition

Needs Center caps and this photo was before I got new tires a few days ago...