Minnesota Focus Owners Club

My dad's been getting a system too lean code for quite a while now in his Focus and it's definitely getting worse. The car drives fine and dandy on the highway but when he comes up to a stop (sometimes, not always) the car will stumble pretty badly, barely idles.

Has ~80k I think and has recently replaced the fuel filter (today). Also tested fuel pressure coming out of the pump and it's 50+ psi so that should be no problem.

So for p0171:
P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs:
Fuel system
Excessive fuel pressure.
Leaking/contaminated fuel injectors.
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Vapor recovery system.
Induction system:
Air leaks after the MAF.
Vacuum Leaks.
PCV system.
Improperly seated engine oil dipstick.
EGR system:
Leaking gasket.
Stuck EGR valve.
Leaking diaphragm or EVR.
Base Engine:
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2Ss.
A SHRTFT-1,2 PID value between -25% to +35% and a LONGFT-1,2 PID value between -35% to +35% is acceptable. Reading beyond these values indicate a failure.

Which means about a hundred different things good be wrong Visually inspecting the vacuum hoses I don't see anything wrong with them. Tried cleaning the MAF with no luck either. I also found a few things suggesting a DPFE/EGR problem which would make sense I guess here: http://www.focushacks.com/index.php?modid=80

Maybe the EGR is staying open and causing the car to stumble like that at idle. If anyone has had DPFE failures before I wouldn't mind hearing some of the symptoms

From here I guess I'll try and catch it while it's stumbling and disconnect and plug the EGR feed to see if the idle improves. Thanks for reading my super long post

double post FTL

sounds like the same problem I am having.
threw the same code too.

Deagle50ae wrote:sounds like the same problem I am having.
threw the same code too.

Well what is the problem?

It's a DPFE. I'd bet my spare change on it.

They are notorious for going out. I also think last time I had one die out (on Merrily's car) that was the same code it threw.

on a spi if it were a DPFE it would give a po401 or a po405 insuf flow or exsesive flow. on a for a lean code will set by a unmetered air leak( I.E intake tube, intake gasket) or a O2 thats being an untard the best way to test the EGR is take and put A SMALL AMOUNT of vaccume (via a diagnostic vac pump) at idle the car should start to stall, if not you sir need a EGR valve