Farty EGR

[GZ123]

I've got a 1998 4.6L. I'm reading the common P0401 code meaning insufficient exhaust recirculation. I bought the truck in March and since I've had it, it has always had this farting sound from the drivers side under the hood right after I shut off the engine. The sound last about 5 seconds. The code has just recently started popping up over the past few weeks. I've noticed rough idling, particularly in reverse, which is also new.

From reading the internets, I'm pretty sure that some component of the EGR system is wigging out, but wanted to ask you guys if the farting sound is indicative of a specific component? Valve? Solenoid? Tube? Just clean the intake?

Any help would be much appreciated.

 

[yockmyer]

Maybe too much gas???? <sorry>

 

[GZ123]

Hah, well played sir.

 

[yockmyer]

Low hanging fruit.....and my 12 yo mindset.

 

[GZ123]

Just took a 10 mile roundtrip drive with max speed of 55 mph and had a P0304 code, Cylinder 4 Misfire Detected. This happened while traveling slightly uphill, going 55, and rpms probably around 3k.

When I got home I opened the hood before I shut off the engine so I could locate the farting sound. It seems like it's coming from the solenoid. Would a faulty EGR solenoid cause a misfire in cyl 4, or am I just super lucky and have two problems to deal with??

 

[GZ123]

NAPA had a cheap EGR solenoid, so I replaced the buzzing unit. The new unit also buzzes, and still getting a P0401 with rough idle ..bummer. Since EGR valves are much cheaper online, I'm going to order from rock auto and have to wait for shipping. Maybe disassemble the throttle body and check for carbon clog tomorrow per this video: .

 

[Ulver]

Don't order the EGR valve yet!

Check your EGR Pressure Feedback hoses for wear and tear, and also, remove and look inside of your throttle body where the EGR valve connects to, to make sure there is no carbon build up. Once you've removed the throttle body, there will be 2 ports that will more than likely have extreme build up. It's very common, so check it before doing anything. Also it would be best to order a throttle body gasket since you're taking that off anyways.

 

[GZ123]

Thanks Ulver. Getting after the throttle body clean out today. I'll check the hoses in the EGR Pressure Feedback Sensor as well and report back so future troubleshooters have a trail to follow.

 

[GZ123]

I opened up the EGR spacer and throttle body today. The throttle was pretty dirty, so that got cleaned. The EGR Spacer body was BAAAAD. The two ports going to the EGR valve were so caked with coke that it was mounding up and out of them. Got that all cleaned up and put everything back together.

...still running rough after the clean out

I've ordered a new EGR valve, so hopefully that does the trick. While taking apart the throttle body and EGR spacer today I noticed that the fuel vapor separator tube that goes from the EGR spacer to the evap service port is rotted. I'm not really sure if the existing hose leaks, or if a leak in that hose would contribute to the problems I'm having, but I ordered a new one.

I got the same P0304 code today (misfire on cylinder 4) I'm worried that since the same cylinder is misfiring that this is a separate issue from the EGR code. I'm sure the plugs and coils are ancient so those may have to get replaced as well.

 

[Ulver]

It's VERY tempting to buy a new EGR valve after seeing that code. I understand that you probably want to throw a part at it and cross your fingers. I've been there.. But diagnosis will save you time and money. You probably should have waited a while to see if the insufficient exhaust recirculation would disappear, or come back, depending on if you cleared the codes or not. It takes a while for that code to clear because your vehicle needs to go through specific cycles before passing the egr test. Check this page out that'll tell you about the drive cycles and how to complete them. https://www.smogtips.com/smog-question/3619/How-Do-I-Perform-a-Ford-Expedition-Drive-Cycle

I had the same issue with the carbon build up in those 2 ports, and the code went away after a while. I highly doubt that replacing the EGR valve will fix how rough it's running. My advice would be to forget the insufficiency code and EGR valve, wait for the insufficiency code to clear and focus on the rough engine..

Which I believe that your misfire is a separate issue, which is why you're probably getting that cylinder 4 misfire. Those 2 situations with the EGR system and cylinder misfire are generally different issues. No worries, it's not that bad.

Before replacing anything, swap your cylinder 4 coil with the cylinder 3 coil, or any coil for that matter. After a while, check to see if the code moves to cylinder 3. If the code moves to cylinder 3, then replace the coil on plug.