I have a 2002 Ford Focus SPI with around 110,000 miles. For the past couple of months I have had the issue of the engine shuttering at around the 35 - 45 mph mark. This is what I have done so far to the car:
1. Replaced the EGR Valve and Tube (was damaged)
2. Replaced the DPFE sensor
3. Replaced the EGR Solenoid
None of these fixes solved the shuttering problem. What did though stop it was actually taking the boot off of the EGR Valve and blocking it off. After learning that trick I thought replacing the DPFE sensor would stop it but it didn't.
This vehicle has also had within the past year:
1. Fuel Filter replaced
2. Fuel Pump replaced
3. Motorcraft Spark Plugs
4. New Coil Pack
5. Ignition Wires
I have checked and re-checked for any major vacuum leaks and cannot find any. The only thing I did find was that the connection to the charcoal canister was a little loose but the snaps were pass the lip.
The car does get the occasional P0442 code in which:
1. The gas cap was replaced
It comes and goes but still cannot find any small holes and/or cracking on any lines. I have not though taken it to get a smoke test done.
I can smell exhaust around the engine block (faintly).
I have ran Sea Foam through the system and can hear all injectors firing. I can though tell you that during the cold mornings / months the car will have a hard time starting. This morning whenever I went to prime the injectors I did not hear the fuel pump engage. It took 3 times to prime before I heard the fuel pump kick on. Once it did turn over it promptly died. This will take about 3 more times before the car actually stays on.
With that issue I did:
1. Replaced the Headlight Relay with the Fuel Pump Relay
This did not have any effect on the starting problem. Also the vehicle idles like hell.
I do want to thank the countless messages that I have read on this forum as they have been a TREMENDOUS amount of help. Unfortunately most, if not all of them have not solved this ongoing issue.
Thank you in advance!