Rough idle after EGR replacement

[08TXExplorer]

Hello everyone. First time posting. I have a 2008 Explorer with the 4.0 that started throwing the P0401 code. I decided to replace the whole EGR assembly because the sensor and solenoid are all connected. The removal was not too bad (bolts were a bit tough to loosen and there was not much room to loosen the 1 1/16" compression fitting from the manifold). Installation was not too difficult either. I made sure the metal gasket indention was toward the front. There is no longer any code or check engine light. Assuming everything was installed correctly, I am not sure why the truck idles rough (cold and warm). It idles around 650 to 700 rpms. It seems like it is starving for gas or sucking in air. I have checked and rechecked anything that I moved or may have bumped during the EGR replacement. I did a visual inspection for any leaks but did not see any. I am at a loss as to why it idles rough (and has lower performance) after replacing the EGR. Any suggestions? Thanks in advance.

 

[steve6534]

Hello everyone. First time posting. I have a 2008 Explorer with the 4.0 that started throwing the P0401 code. I decided to replace the whole EGR assembly because the sensor and solenoid are all connected. The removal was not too bad (bolts were a bit tough to loosen and there was not much room to loosen the 1 1/16" compression fitting from the manifold). Installation was not too difficult either. I made sure the metal gasket indention was toward the front. There is no longer any code or check engine light. Assuming everything was installed correctly, I am not sure why the truck idles rough (cold and warm). It idles around 650 to 700 rpms. It seems like it is starving for gas or sucking in air. I have checked and rechecked anything that I moved or may have bumped during the EGR replacement. I did a visual inspection for any leaks but did not see any. I am at a loss as to why it idles rough (and has lower performance) after replacing the EGR. Any suggestions? Thanks in advance.

I would strongly suspect a vacuum leak from the new EGR assembly. To troubleshoot start the engine and open a propane torch near the EGR valve (don't light it though). If there is indeed a leak you should hear the engine speed surge from the intake of propane into the engine.

 

[08TXExplorer]

Thanks Steve. As I do not have a propane torch handy, I will either need to find someone who does or look for alternatives. I do have carb cleaner but am a little nervous about using something flammable like that (as I have seen suggested on the interwebs).

 

[08TXExplorer]

I tried finding a leak with water while the engine was running to now avail. Is there any other 'home remedies' that I can try before purchasing a propane torch?

 

[fordbluefamily]

Did you disconnect the battery for a while to let it "relearn" things? Try that first as it is very free and easy.

 

[08TXExplorer]

Thanks fordbluefamily. Other than the having it disconnected during the EGR replacement, the battery has not been disconnected for any length of time. I will disconnect it over night and see how it is tomorrow.

 

[Stiff]

I had a rough idle a few weeks ago, not from the EGR valve although I did trouble shoot mine to make sure it wasn't the culprit. I had replaced the plugs and wires and 3 of the wires were bad. So I replaced those and found a set of Motorcraft. The issue was two plugs gaps and gotten smaller so I must have bumped them on install and there was a vacuum leak underneath the air intake manifold. Not easy to remove but I pushed the vacuum line back in and problem solved. There was still a very small roughness so I ran a can of seafoam through the tank and now it's good.

Just some things from my experience a couple weeks ago. Not sure if it's worth it or not.

 

[08TXExplorer]

I disconnected the battery overnight and then took it for a 30 mile drive today (while making several stops). It did not seem to change anything and still idles rough.

One of my stops was to Home Depot where I picked up a propane torch. I tried unsuccessfully to make the engine increase while using the propane torch around the EGR, the TB, intake manifold, and any vacuum lines that I could easily see or get to. I guess that would be a good thing (if I truly do not have a vacuum leak) but it still idles rough.

Any other suggestions?

 

[fordbluefamily]

Hmmm. My next step would be to throw my OBDII on it and look at the misfire data, or any other clues to what could be happening.

 

[suzook]

Hello everyone. First time posting. I have a 2008 Explorer with the 4.0 that started throwing the P0401 code. I decided to replace the whole EGR assembly because the sensor and solenoid are all connected. The removal was not too bad (bolts were a bit tough to loosen and there was not much room to loosen the 1 1/16" compression fitting from the manifold). Installation was not too difficult either. I made sure the metal gasket indention was toward the front. There is no longer any code or check engine light. Assuming everything was installed correctly, I am not sure why the truck idles rough (cold and warm). It idles around 650 to 700 rpms. It seems like it is starving for gas or sucking in air. I have checked and rechecked anything that I moved or may have bumped during the EGR replacement. I did a visual inspection for any leaks but did not see any. I am at a loss as to why it idles rough (and has lower performance) after replacing the EGR. Any suggestions? Thanks in advance.

Check the wires that connect to the throttle body. The one harness that has the 4 wires. I just changed my egr, and noticed all 4 wires had broken insulation right where the loom ends, and the tape is wrapped. It's a tight bend on the wires and after time they crack. You might have to unrap the tape. Take a look.

 

[08TXExplorer]

sorry for the long delay - holiday time... Anyway, I had a guy with a nice OBD II connect to my truck and he determined that the new EGR was sticking open a little and causing the rough idle. I took off the new EGR and swapped it for another. It is running much better. However, I have a new problem, sigh. The two small hoses (one is red, one is black) that connect to the intake manifold, the black one has broke in two. According to Oreillys, this is a dealer only part and it is sold as a kit that requires cutting and splicing in multiple hoses (not just the one that is broken). Is this true? What exactly are these hoses (I assume they are vacuum)? Is this the correct way to fix it?

 

[fordbluefamily]

Vacuum... Find some rubber hose that slides over it and use it to splice the two halves together. The plastic hose gets brittle with heat/age.

 

[suzook]

Vacuum... Find some rubber hose that slides over it and use it to splice the two halves together. The plastic hose gets brittle with heat/age.

Not sure where ford gets its plastic/rubber from. It's literally just falling apart. Unacceptable for only a 10 yr old vehicle.

 

[fordbluefamily]

To be fair, every time I see that plastic line under the hood of something, I avoid moving it. It is always brittle and not just when its 10 years old.

 

[suzook]

To be fair, every time I see that plastic line under the hood of something, I avoid moving it. It is always brittle and not just when its 10 years old.

My 18 yr old pathfinder had not one brittle wire or rubber hose. I have seen bad insulation on 5 yr old fords. There's something wrong.

 

[08TXExplorer]

Ok guys. Need your help once again. To continue the story.... I sucked it up and purchased the vacuum assembly from the dealership because the break was so close to the boot that there was no way to splice it. So, after getting the new tube assembly, I noticed that all connections would be easy except for one. There is a little vacuum pigtail that connects to the fuel system UNDER the intake manifold. I tried for hours to get the new hose on with no luck. So, I took a deep breath and removed the intake manifold and everything connected to it. I made the connection of the hose, replaced the intake gaskets, put the intake back on, and connected everything back up and then connected the battery. I double and triple checked all my connections that I had removed/touched. I connected a code reader while the key was on but engine was off. It said no codes. Great. However, when I try to start it, it turns over but immediately dies - every time. Do I need to rev it at a certain level to warm the engine and reset the PCM (I read that somewhere)? What should I check?

 

[Flag Gibby]

Try resetting the fuel inertia switch just for the hell of it and make sure that there are no issues with your MAF sensor and throttle body connections.

 

[08TXExplorer]

Hey guys. Problem resolved (for now). This latest issue was caused by an intake gasket not being seated properly. When I removed the intake manifold tonight, one of the six gaskets was laying on the top of the block. Once I replaced it, put everything back together (I also took advantage of having the intake off and replaced the PCV valve that I had), it fired right up. No codes as of yet. Will drive it for 60 or so miles and see if any codes re-appear. I also temporarily fixed a couple wires that had become bare due to the shielding being so brittle. Thanks to all for the suggestions and comments.