Explorer throwing codes, but no driveability symptoms

[SexyExy]

My ex is throwing the following codes: p0171 p0174, lean banks p0402 excess exhaust re-circulation. Pulled the codes on my cheap chinese vgate (which I highly recommend) Car has 127k miles and starts, runs, idles and accelerates well. Previously the car was idling a little rough, but after I swapped a bad spark plug it ran very well and I thought that the codes were fixed, codes seemed to take longer to appear at the very least after the spark plug swap. Users experiencing similar codes were advised that the DPFE was likely to blame, mine does appear to have the older metal housing, should I bite the bullet and buy a new sensor even though I literally have no symptoms or is there something else that could cause this?

Also, this is my first post in this forum, have been lurking for while although I'm fairly certain there I'm rocking a bumper sticker from this site on my rear window from the previous owner. So although, while I am new around here. My car probably is not.

 

[SexyExy]

DPFE arrived today, 402 seems to be solved need to drive a little more to verify, p0171 and p0174 came back almost instantly though.

 

[SexyExy]

Idle moves around the mid to upper 700s, 760-790s. needle appears steady, values obtained from code reader, not cluster.

 

[jremington59]

When it's cold, start it and spray a little starter fluid around the intake and see if the idle changes.

 

[SexyExy]

Ive done the enrichment test a few times now and I havent been able to notice a difference in engine speed, used propane twice and maf cleaner once (its flammable so I assume it would also work. There may have been a change in speed when I hit the front of the manifold but I couldnt duplicate it. Also there seems to be an oily substance in the coolant. Possibly oil. I would like to retorque the lower manifold, can someone who has done their intake gaskets chime in and tell me what needs to be removed in order to retorque the intake? I could access 1 near the coil pack that was barely finger tight, tightened it up but I know there are more.

 

[Afboy143]

On my SOHC, I couldn't reach the lower intake manifold bolts without removing the upper intake manifold.

It sounds like a gasket replacement is in order for you (upper and lower).

 

[SexyExy]

I have the older pushrod motor. On a side note I havent noticed any coolant or even any oil loss for that matter, only have owned it for a few months, so there is a possibility that its actually stop leak and not oil in the coolant. The oil appears to be only oil. Really hoping a headgasket isnt in my near future. Truck runs well apart from the lean CEL codes and mystery liquid in coolant.

 

[SexyExy]

Just changed out my sway bar links today and while I was heading to home depot to purchase my new li ion makita reciprocating saw (which is awesome) I noticed that when accelerating when the engine speed is under 2k if the trans does downshift I get a mild stutter/hesitation, is this consistent with manifold gaskets, which I have already ordered or is something like my fuel pump or filter more likely the issue

 

[SexyExy]

changed upper manifold gasket and fuel rail gasket, also did plugs while i was at it, the truck definitely feels more powerful than before and I have yet to see lean codes again.

*crossing fingers*

 

[SexyExy]

Has been a few weeks and a few hundred miles, I can safely say that the all the CEL has been solved, and the engine stumble was seems to be related to the incorrect spark plugs that were mistakenly sent to me, SP413s for the modular ford engines.

To sum things up anyone experiencing p0171 and p0174 who has eliminated vacuum leaks should change their upper manifold gaskets and fuel rail gasket.