Codes P0390 and P0394

[sethsn]

Hi - I'm a newbie here so forgive me if I inadvertently create any faux-pas!

I have a 2012 Expedition XL police spec that is 257K young. It's throwing both P0390 and P0394 codes and has the very low rattly idle issue associated with a broken sensor. I replaced both cam position sensors and nothing changed. So I started digging ...

The low idle seems to occur mostly when I put it into reverse and then give it some gas (e.g. reversing up our sloped drive). When it does occur all live data from the cam position sensors stops - flat lines as 0 for both sensors. Once it's stopped I have to reset the scanner (Foxwell NT710) in order to get data back.

Has anyone seen this or have any suggestions? I need to clear these codes to get it through smog.

Many thanks

Nick

 

[DieselMonk]

Chaffed wire, bad pins or corrosion in the connectors, all the timing components inside the engine like chain, tensioner etc.
First I’d make sure the cam sensor signal doesn’t cut out.

 

[sethsn]

What's weird is that the engine goes back to running normally after a short while but the data never returns. I've updated the firmware in the Foxwell just in case ... I'll try again tomorrow after inspecting everything

 

[DieselMonk]

That may be a thing with that Foxwell scanner. Maybe try borrowing a different scanner from a friend.
At first you have to establish what electrical shenanigans are going on here: Is it the crankshaft position sensor, Canbus signals, etc. and then you have to get the wiring schematic and test each wire and connector involved with that circuit that’s acting up.

 

[sethsn]

As a short term measure what is the risk of disconnecting the cam advance solenoids? It will certainly reduce performance but it will also (hopefully) prevent the really low idle when they timing remains advanced.

 

[marinec37]

Did you find the issue? Please share…

 

[Macho grande86]

I have this same issue. I was hoping to find a resolution in this thread