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Thread: ZETEC Engine stumble - SOLVED Reply to Thread
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Topic Review (Newest First)
02-27-2015 05:39 PM
beyond_theft dont think it has ever been changed i could try it but im stuck on thinking its my timing all my problems started after the belt got changed i knoticed it about not even a week after i think it jumped. Also if its the timing im just going to go buy another engine cost less and its at 280,000km im gonna test my egr and dpfe see if there is any change i have access to a mechanic shop just no help im relying on you guys so i can keep my wagon

were you having the same issue before the fuel filter? i can also take a video of it running and give you a link on youtube.
02-27-2015 12:42 PM
MadFF When was the last time you replaced the fuel filter? It made a noticeable difference when I replaced mine.
02-26-2015 07:21 PM
beyond_theft ive replaced this hose, still stumble and rough idle cleand the maf and iac valve. I'm doing the mounts but i really dont think it will help. Scanned it has no codes ive tested the idle to figure out when it startes to be rough and sputter starts around 700 and stops at 1100 i used a snap on scanner. I think it is my timing belt could have jumped? i dont think its running lean cant smell unburnt fuel.. any suggestions?
01-22-2014 08:58 AM
qdeezie I installed the new hose last night and low and behold, the stumble is GONE!!! The car runs like a totally different vehicle now and it accelerates much better too.
01-20-2014 10:12 AM
qdeezie I'm another victim of the bad hose. I reached around the back of the engine and sure enough, the hose was collapsed. I used a pocket knife to cut it off and a screwdriver to pop the clamp. I'm waiting on my new hose (with the heat wrap around it) to come in.

I'm glad I found this thread.
08-18-2013 05:27 PM
Error code P2195 on 03 ZX5

Was getting error code P2195 on 2003 ZX5 Focus my wife drives. I replaced fuel filter, upstream O2 sensor, cleaned MAF and throttle, still no luck. I finally took to the 'net and found this thread. It turned out the rear PCV/Crankshaft hose was indeed the problem.

Unfortunately, today was a Sunday so I had no choice but to "frankenstein" a hose together that would work. I just used hoses and some elbows from off the shelf at my local Autozone. Hope this helps someone else, as the car is running better than I've ever seen it.
04-04-2013 01:06 AM
amc49 A bad TPS switch can really mess with idle and off idle too, just went there last week. Put a manual TPS on ATX to avoid buying the TB, works perfectly now and idle trouble is gone.
04-03-2013 10:12 PM
larrydoood This could be causing a lag or stumble on quick acceleration:
02-18-2013 11:59 PM
jakeru It's been about a month and the Focus has been consistently driving like a dream under all conditions!

Just replaced the front brake pads (Mintex A/F from BAT) and front swaybar end links (Duralast from autozone).
01-17-2013 12:35 PM
jakeru Hey guys. Just diagnosed and fixed a couple problems with my wife's Focus (a 2001 Street edition, automatic) last night that includes the leaky PCV hose issue discussed in this thread. The other problem I found and fixed at the same time was the compression fitting that connects the exhaust tube to the EGR valve was completely unfastened.

I diagnosed the damaged PVC hose by spraying solvent (non-chlorinated brake parts cleaner) around the vacuum line connections with the car idling (while it was idling poorly and roughly). I noticed that in a certain area, the spray caused the engine RPMs to rise. Then I looked more closely in that area and found the collapsed PVC hose, with the hole in it. The hole was making a pretty loud sucking noise. I zero'ed in on the source of this noise with a mechanic's stethoscope. I noticed that the PVC hose was oxidized and cracking, but the area near the bend was the worst. The part number XS4G-6N664-AA was marked on the hose.

I fixed the original PVC hose by coiling up a wire (1/16" diameter stainless steel) and shoving it up inside the hose (at the weak, larger diameter portion of the hose) to reinforce it and help prevent it from collapsing under vacuum. I then used several layers of Gorilla tape (a crazy strong duct tape) all over where the hose had a cracked outer surface, to seal the leak and further reinforce the hose. I managed to re-install the original hose clamp (after re-forming it a little) using some 5" vice grips.

I also fixed a disconnected EGR fitting I noticed (for retaining the metal exhaust tubing to the PVC valve) by basting the threads with antiseize, and simply reinstalling.

Pulling Fuse #9 cut power to the ECU (note: if ECU is off, turning key to accessory position will not display miles on the odometer). This might have been necessary or helpful to reset it so the engine can re-learn its EGR and idle air control valve settings.

After fixing the vacuum and EGR leaks, each of the following symptoms disappeared!
1. car was idling rough and misfiring, in particular at warm/hot idle, and would occasionally even die. Combined with unburned exhaust gas smells out the tailpipe. This behavior was fairly recent (last month or so.) Fault code was also stored in ECU about the mixture being too lean.

2. throttle was difficult to modulate in certain light throttle conditions (like getting going from a stop). Engine would "surge" in power if throttle wasn't modulated super-carefully just off idle. I tried recontouring the insides of the throttle body (removing a riveted on plastic baffle from the throttle plate, and removing some material inside the throttle body to try to fix this problem years ago, but it just changed the position at which the surge occurred towards a lighter throttle position.

3. shrieking/squealing noise was being emitted from engine compartment in certain light acceleration conditions (generally whenever the throttle was pushed down about 1/4-1/2 of the way.) This behavior was going on for years. I incorrectly had assumed it was due to an aftermarket panel airfilter.

I am delighted that some of these problems I just thought were "quirks" with the car, are now fixed! A few days ago, I installed a first new set of spark plugs, (at 90k miles) to try and fix the idling, but it didn't make any difference. Although I have no regrets replacing the plugs at 90k (maintenance interval calls for 100k replacement interval).

My plan is to obtain a new, updated XS4Z-6N664-BA hose to have on hand in case any further problems with the PVC hose should develop. Thanks for the helpful info in this thread for helping me to locate, confirm and address this problem.

Originally Posted by Charged SVTF View Post
Good afternoon Gang...

Has anyone substituted the YS4z-6N664-BA with the XS4Z or Vice Versa?
I don't think the YS4Z would fit properly on my 2001 Focus Street Edition automatic; it has a module of some sort (maybe an ABS controller but that's a wild guess) against the firewall, which looks like it would interfere with the longer bend of the YS4Z hose.

I have a feeling that the XS4Z hose might fit on a car where the YS4Z hose is specified, however I feel that the gentler radius bend of the YS4Z hose might be more resistant to not collapsing under vacuum.
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