Q: My 2002 Ford Expedition is running too lean with misfires.

asked by on

02 Ford Expedition 4.6L 173k miles with K&N air filter check engine light came on code bad egr valve I replaced that but trans would stick accelerating up shifting especially freeway speeds. Days later other codes came up too lean for conditions bank 1,2 and cylinder 4 I then changed spark plugs, pcv and pcv hose, battery and swapped out 2 coils cyclinder 3,4 and finding now it will not go faster than 30 mph. I changed the trans speed sensor but nothing changed. I have vacuum to the egr valve top of engine driver side completely dry while passenger side very wet oil and coolant leak from heater core especially in spark pug wells 3,4 cylinder. Everything ran fine before heater core was changed first it was venting allot into cabin then after venting allot in engine bay. An auto shop scanned it and looked at saying. The vehicle probably was submerged in water. The codes they was getting cylinder 2,3,4 coils bad and trans reading 9000 rpms sitting still.

My car has 17200 miles.
My car has an automatic transmission.

Hello. It sounds like you may have a few issues going on here. I usually start by checking the codes in the computer myself. This will give me a good idea of what my be going on and what cylinders are having issues. The most common problem to cause misfires on this engine is bad ignition coils. These are common failure. I will usually test them either by switching them to see if the misfire changes or test them with an ohm meter. I then remove the spark plugs and inspect them and do a compression test. This engine also has a history of bad valve seats which will cause all of these issues. All of these need to be checked first. At that point the intake manifold needs to be checked as I have seen a lot of these with cracked intake manifolds that will cause this. You should have this checked out by a certified mechanic, like one from YourMechanic, that can come to you to [diagnose why the engine is misfiring] https://www.yourmechanic.com/services/engine-is-misfiring-inspection

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. My 2002 Ford Expedition is running too lean with misfires.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Emergency brake stuck on the floor

It sounds to me like the return spring may be to blame here. Try pulling back on the pedal while pulling the release handle. If it still wont move, look and make sure the release handle is pulling the release...

Q: I have a oil leak and i have noticed that there is oil at the top of my hood and on the right side by the tire. What is causing th

Hi there: Usually when oil is splattered all over your engine compartment, it's due to oil leaking from the front or side timing cover or oil seal. When the oil leaks out, it hits the serpentine or drive belt and...

Q: Check engine light on 1998 Audi A4

Any good mechanic can check them out. Here's the problem that you've got though--when there's a linking error, either the nanoport isn't working right because one of the pins is bent or there's wiring short somewhere in the computer system...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...