Exhaust/emissions problem or fuel pump/filter?

[butchhuskey]

So my '01 Focus ZX3 started showing the common Focus problem of driving rough, a lot of jerking and hesitating and it felt like inconsistent power delivery. It would idle all day long just fine so I i figured it wasn't a fuel pump, the problem was leaving from a stop the motor would start to die and then the ride would be jerky.

Going through the forums the DPFE sensor seemed like a good place to start, especially since it was pretty cheap and easy to replace. After putting in a new one the problem went away completely. For 20 minutes. It was fine on my way to work but I had a couple times on my drive home where it hesitated again. Now 2 days later it barely will even start, it idles really rough and loud, which wasn't an original symptom, and dies immediately after giving it some gas. This seems more like a fuel issue, but why did the DPFE change help, and why for just a short while?

Just a little more info, my CEL came on when the car first started hesitating, it didn't go out when the sensor was replaced or after disconnecting the battery, but I didn't disconnect the battery until the new problems started. I don't have a code, and at this point I think I would have to tow it somewhere to be diagnosed, I'd love to try a few things though before I pay for a tow and have a garage take over though.

[BC_ZX3]

Other easy things to check: coil pack electrical connector (look for exposed copper, green copper corrosion or loose wires), the coil pack itself (look for cracks on the underside).
Your problem sounds electrical, not fuel related, to me. Under load, seems like your ignition system is crapping out.
DPFE sensors problems usually give "hunting" or surging symptoms during part throttle cruise.

[amc49]

If afraid of the EGR and DPFE then pull vacuum hose to the EGR valve and block hose, that takes EGR out of the tuning problem unless valve itself is leaking.

[ZXthrizzle05]

both are good answers

[butchhuskey]

Thanks, I bought a new coil pack today and while I was putting it in I noticed that on the pigtail leading to the coil, the middle wire was sheared off. The shitty thing is I probably did it. The new coil pack is on, but I'll have to get a new connector before I can see if that solved my problem.

What I still don't get is why the symptoms went away with the new DPFE sensor but for just a short time. The current (no pun intended) problems definitely seem more electrical, but the first couple days of having issues starting the car wasn't one of them.

[amc49]

Luck of the draw maybe..........regardless, make the resulting lead longer when patching in the connector, the stock length is too short, the reason why the MAF pulls up on harness to break it there at the coil.

[BC_ZX3]

Originally Posted by butchhuskey

... the middle wire was sheared off. The shitty thing is I probably did it...

If it was weak enough to brreak by simply tugging on the connector, it likely was a problem.

Originally Posted by amc49

Luck of the draw maybe..........regardless, make the resulting lead longer when patching in the connector, the stock length is too short, the reason why the MAF pulls up on harness to break it there at the coil.

^ X2