'05 Focus with stumble/miss, no codes

Wife's Focus has an intermittent stumble, particularly when accelerating from a stop.
New plugs and coil packs, fuel pump works fine, fair amount of pressure in crankcase at idle (suspect PCV issue and/or PCV hose is cracked).
She drove it a couple of times and it stumbled, stalled, then threw a code which I accidentally erased before I could read it (thanks Mac tool scanner).
I drove it 3 times since it cut out and it never stalled or threw a code for me, despite putting it through the paces and through heavy traffic (thanks Toronto construction).
R&R of the PCV is a b!tch 'cuz it's tucked under the intake manifold (thanks Ford)
Any suggestions before I attack the intake?

Did you try cleaning the MAF?
Does yours have that goofy non replaceable air filter?
Vid below shows how to remove.


https://www.youtube.com/watch?v=U9PT8ZN3TXI

This is the kit I bought to bypass the "lifetime" filter when I had my '05.

http://www.steeda.ca/ford-focus-part...atec/555-3104/

If it has a "lifetime" filter, good chance it's not in good shape.
Ridiculous on Fords part.

Yep, came with a lifetime air filter. Not a serviceable part.

From the Focus Fanatics site

The 05-07 Focushave a lifetime sealed filter that Ford says never needs replacement. The only way to know for sure if its done is to look at that clear sight glass located on the intake tubing that has a green section and a red section with a yellow bladder in the middle. If that yellow part moves to the red part of the sight glass then you know the filter is plugged up and needs replacement.

Best part about ditchin it, car will run better vs than it ever has (quote from Scott B).

Quote:

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Originally Posted by ZR

Best part about ditchin it, car will run better vs than it ever has (quote from Scott B).

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Yep, made a big difference in my case. Cleaning the MAF also really helped.

Got a nice CAI in there now.
Only cleaned the MAF once with circuit board dust spray as I understand the slot-style MAF is sensitive to cleaners.
Would a malfunctioning MAF not throw a code?

We use nothing but brake cleans on em here. No idea if what you used is a good, bad or indifferent choice.
Did it run differently after cleaning?

no, MAF was cleaned when the CAI was installed about 2 or 3 years ago.
I guess it's that time.

Start there.

Dirty TB or IAC?

Update: cleaned IAC, problem prsisted. Apparently the EGRs on the Duratecs are notorious for causing problems without throwing codes. I just pulled it off this AM (damn thing is hidden by a coolant distribution block which is hidden behind the battery). I cleaned it, but it doesn't look too dirty. Not sure if I will reinstall or buy a new one ($140 for a whitebox unit!!!!).
If this doesn't fix the stumble, I will look at the PCV and hose (which is buried under the intake and may necessitate removal of the rad)...

Installed the whitebox EGR and no difference - slight stumble at idle after warm-up, slight hesitation upon accelerating from a stop, down on power when cruising.
I now suspect the PCV valve and hose.
Still no codes although the traction control light is on and I can't turn it off.

I'd back up and have the car scanned for the Traction control code. Sure your not feeling traction control cutting in n out cutting power?

Those cars are notorious for wheel bearing problems.
Bad bearing throws a trac lock code.
Maybe the cat is plugged?

ZR - it doesn't feel like traction control is engaged, but hard to say for sure as I've never experienced TC activate while driving 30 km/h on flat, dry pavement. I will scan, but there is no CEL light, just the TC light.

Frankie - no indication that a wheel bearing is faulty - car coasts fine with no howling/growling. TC light appeared after R&R of battery. Cat is the original unit (187,000 kms), although the intermittent nature of the problem, commonly at low rate of acceleration, suggests it is fuel/vacuum related.

OK, after looking at it with fresh eyes (and reconnecting the TPS - DUHHH!) she fires up and seems to run perfectly, but it has fooled me before.
I'll keep tabs on performance and mileage and hope that it throws a code if/when a problem arises.
Current opinion is the EGR was sticking and causing a stumble.

EGR was culprit of bad shudder on my GF's

It returned many kms later and was a failing fuel pump. Ended up doing full tune up, wires, plugs, coil, filters, etc and it runs like a champ now.

Looks like the PCV hose split and created a vacuum leak.
Glad I did the ignition and EGR, but this is definitely the cause of the stumble.
Intake needs to come off and I plan to install a catch can and remote PCV valve. Total PITA.
Can anybody recommend a good catch can with 5/8 barbed inlet, drain cock, and provision for a 1/2" grommet? Looks like I'm doing the soup can mod again.

Done.
Pic of offending PCV hose which caused a vacuum leak but no codes:
http://i1062.photobucket.com/albums/...atec%20010.jpg

I'll post a link to my fix with greater detail once it's up on another board.

Wish they'd get their act together on some of these kinda issues. Been having mystery PCV hoses splitting since the Windstars then carried it over to the several models that followed.

Finally posted the fix on the Focus Fanatics website (pg 14, #136):
http://www.focusfanatics.com/forum/g...cement-14.html
Even the wife notices the improvement - this thing feels peppy!