My 01 has been giving me fits for a while, any help is appreciated.
Recently noticed a rough (Hunting/Surging) idle, which gets progressively worse when it is up to operating temp. Almost seems that it has a really bad miss. However, if I put it in gear and step on the fuel a bit the miss goes away but the hunting/surging issue still persists. RPMs swing from about 500-900 when its doing this.
When in gear stopped it still does it but it is very faint. Also, if I rev the engine up past 800 rpms in neutral/park it doesn't idle down, it simply dies.
After all of this started, I noticed that the CPS (control pressure sensor on the drivers side oil rail) was leaking oil past the sensor, so I changed that with an OEM one and replaced the harness. I also was getting multiple IPR codes so I went ahead and changed that as well (also OEM).
Now, this thing is still doing it! I pulled the codes and am getting a lone P1670 code WITHOUT a check engine light. Still runs great on the highway, I'm stumped. I started it up hot this morning and messed with the connectors going to the UVC harness without any change to the rough idle issue.
Truck has around 403,000 miles and is auto/4x4. Nothing done to it other than a straight pipe and re-routed CCV line. Always changed the oil and fuel filters with Motorcraft brand and Rotella T 15W40.
Recently noticed a rough (Hunting/Surging) idle, which gets progressively worse when it is up to operating temp. Almost seems that it has a really bad miss. However, if I put it in gear and step on the fuel a bit the miss goes away but the hunting/surging issue still persists. RPMs swing from about 500-900 when its doing this.
When in gear stopped it still does it but it is very faint. Also, if I rev the engine up past 800 rpms in neutral/park it doesn't idle down, it simply dies.
After all of this started, I noticed that the CPS (control pressure sensor on the drivers side oil rail) was leaking oil past the sensor, so I changed that with an OEM one and replaced the harness. I also was getting multiple IPR codes so I went ahead and changed that as well (also OEM).
Now, this thing is still doing it! I pulled the codes and am getting a lone P1670 code WITHOUT a check engine light. Still runs great on the highway, I'm stumped. I started it up hot this morning and messed with the connectors going to the UVC harness without any change to the rough idle issue.
Truck has around 403,000 miles and is auto/4x4. Nothing done to it other than a straight pipe and re-routed CCV line. Always changed the oil and fuel filters with Motorcraft brand and Rotella T 15W40.
