2002 Taurus Rough Idle

[Kornkat2020]

Hello, I just recently purchased a used taurus and was experiencing rough idling and misfiring during operation. I replaced the EGR valve, the egr sensor, coil pack, spark plugs, iac valve, as well as check for vacuum leaks near all the hoses. I am a novice when it comes to this, but I was able to change those without issue. The misfiring was fixed during driving, but I still have rough idling. The needle seems to stay in check pretty well and the check engine light isn't on, but the car kinda hesitates and it causes the car to rock when idling. You can also feel the stuttering and rocking when cruising at very low speeds (5-15mph). Any ideas? I've already plugged in a decent amount of money into parts and am running out of patience when it comes to fixing what is a "potential" problem, and it winds up not fixing much. Thanks for reading!

[shorod]

Welcome to the forum! To help identify where you should next spend your time and money, you'll want to do some troubleshooting rather than shot-gunning of parts. You need to determine if this is a cylinder misfire, low fuel pressure, vacuum leak, or other. If you have access to a scan tool with datastream mode, you might be able to learn a lot about where you should be focusing your effort.

For example, with the scan tool you'll be able to review diagnostic codes, both current and pending. Just because the Check Engine light is not on does not mean there are no available diagnostic codes. The issue may just not be bad enough to trigger the light. Also, monitoring the Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT) parameters might help you determine if the issue is more likely to be an ignition related misfire, fuel related, or vacuum related.

While you're looking for a scan tool, you could pick up a can of Mass Air Flow Sensor (MAFS) Cleaner and the appropriate security Torx bit, then clean the MAF sensor on your car to see if that helps. Carefully inspect the intake air tubing while doing this, especially where the clamps connect it to the MAF sensor and throttle body and also in the accordion folds.

Checking vacuum at idle with a vacuum gauge could help determine if there's a vacuum leak, but with a misfire vacuum readings can be a bit tricky as well.

If you can get your hands on a fuel pressure tester you can check the fuel pressure at the fuel rail during Key On Engine Off (KOEO) as well as Key On Engine Running (KOER). The KOEO results could help you identify a sticking fuel injector and the KOER results could help you identify if the fuel pump, fuel pressure regulator, and fuel filter are doing their jobs.

-Rod

[infomatrix]

the stuttering noise could come from your belt..no?...

[kem09030]

If you are still having this issue you may want to look at the PCV hose. I had a collapsed hose and it made for a rough idle for a long time. That progressed into stalling when it was above 95 outside and I was slowing down after a long drive. Under about 15 mph is when it would start stuttering then a little slower it would stall. It must be a fairly common failure as the new hose is reinforced.

[shorod]

Yep, it's pretty common. There's a sticky on the Taurus forum main page titled, "Codes P0171 And P0174" that shows some of the common issues, including the PCV hose, along with part numbers.

-Rod

[BeaJean]

Originally Posted by Kornkat2020

Hello, I just recently purchased a used taurus and was experiencing rough idling and misfiring during operation. I replaced the EGR valve, the egr sensor, coil pack, spark plugs, iac valve, as well as check for vacuum leaks near all the hoses. I am a novice when it comes to this, but I was able to change those without issue. The misfiring was fixed during driving, but I still have rough idling. The needle seems to stay in check pretty well and the check engine light isn't on, but the car kinda hesitates and it causes the car to rock when idling. You can also feel the stuttering and rocking when cruising at very low speeds (5-15mph). Any ideas? I've already plugged in a decent amount of money into parts and am running out of patience when it comes to fixing what is a "potential" problem, and it winds up not fixing much. Thanks for reading!

I would suggest checking on your motor mounts, that could be what is causing the car to have a rough idle.