06 EB clunking on mild acceleration

[John Stover]

I've searched the thread until my eyes cross. I picked up a nice 06 in great condition. It's a replacement for my 01. It does have one issue i'm trying to track down. Cruising along 30-50 mph (speed doesn't seem to matter) and about 1500-2000 rpm. Gentle acceleration causes serious sounding clunks in the driveline. It will continue if I don't adjust my acceleration. If i accelerate harder, such as when passing, and it downshifts, there is no clunking. To best describe the clunk, it's as if i had run out of gas, same jerky clunk. Any thoughts or experiences would be welcome before I start throwing money at this Expy. Thanks!

 

[2019ExpeditionMax]

Have the vehicle scanned for any pending codes particularly in the PCM & TCM. I would also double check fluid levels in the transmission and differential, see if there are any obvious signs of any recent work. If you just bought the car ask the owner or double-check the carfax if you got one on maintenance history. That should give you a better starting point.

 

[John Stover]

Thanks for the reply. I bought from a small dealer, primarily because he has a good reputation and actually offers a 30 day/1000 mile drivetrain warranty. He's working with me, but he's an hour away and they've already taken a look. I want to gather real-world info so i can make sensible recommendations. Carfax is clean, fluids topped off. Will have the OBD professionally scanned. (I just have a basic scanner which so far hasn't shown a code. Which reminds me, I get no CEL either) I'll let you know what we ultimately find.

 

[2004XLT]

I had exactly the same symptoms a few months ago. After driving it like that for a while the engine light came on, the code was for the crankshaft position sensor. However, replacing this didn't make a difference. Ultimately it was caused by a failing COP. I never had issues with city driving only highway speed and an occasional stall in reverse.

Most likely you have one or more failing coil packs. I recommend you only replace them with Motorcraft, ebay has the best prices.

How many miles are on yours and do you have service records?

 

[Dustin Gebhardt]

Issues that come up during acceleration are usually ignition-related. It could be spark plugs (only use the Motorcraft ones for these engines), it could be a COP, it could be the coil connector wiring. See if you can find a scanner with Mod6 capability. This will show a misfire if you have one. If you find a misfire, then you can move around the plugs and coils to determine if the issue is a plug or coil or other problem.

 

[Hubert]

I've searched the thread until my eyes cross. I picked up a nice 06 in great condition. It's a replacement for my 01. It does have one issue i'm trying to track down. Cruising along 30-50 mph (speed doesn't seem to matter) and about 1500-2000 rpm. Gentle acceleration causes serious sounding clunks in the driveline. It will continue if I don't adjust my acceleration. If i accelerate harder, such as when passing, and it downshifts, there is no clunking. To best describe the clunk, it's as if i had run out of gas, same jerky clunk. Any thoughts or experiences would be welcome before I start throwing money at this Expy. Thanks!

Hello, I would look at the deferential both front and rear.. the oil should be changed I think after 70k and the oil is vehicle specific so be very careful in the oil that you choose

 

[Hubert]

Hello, I would look at the deferential both front and rear.. the oil should be changed I think after 70k and the oil is vehicle specific so be very careful in the oil that you choose

 

[Hubert]

Issues that come up during acceleration are usually ignition-related. It could be spark plugs (only use the Motorcraft ones for these engines), it could be a COP, it could be the coil connector wiring. See if you can find a scanner with Mod6 capability. This will show a misfire if you have one. If you find a misfire, then you can move around the plugs and coils to determine if the issue is a plug or coil or other problem.

 

[Hubert]

OBD scanner, I would recommend Blue driver, I bought one a few years back for $100.. it's covers alot

 

[John Stover]

Thanks to all, you've given me a couple of paths.