2003 Lincoln Navigator

This began with the CEL (Code P0401 EGR System Flow Insufficient).

The PITA is that my EGR is next to the firewall BEHIND the intake manifold. On my 98 Expy, it's in plain site and easily acccessible.

So I replaced my DPFE Sensor.

1st DPFE from Autozone, reset CEL, no change, CEL remains.

2nd DPFE from Ford (Motorcraft), reset CEL, no change, CEL remains.

So I was told by a parts guy at Autozone that Sea Foaming through the brake booster may clean the EGR thus resetting the light on it's own.

After performing this smoky task to a "T", I hear a rattle when I'm accelerating past 2K RPM in any gear.

In neutral and reving up the engine from idle to 5K, there is NO NOISE.

So resetting my CEL (Pulling the negative cable off the battery for 3 min) and cleaning the IAC ( I read on a Mustang forum somone Sea Foaming their 4.6 and the IAC got clogged, recommended a removal and cleaning) still no change.



Thoughts anyone?

 

Did you change your oil after sea foaming?

 

No, not yet. I'll try it today. The rattle sounds like a big slug in a tin can. Again only after 2K RPM with load (In drive while moving). When I tried a brake torque, no sound... I'll try the oil change on my lunch break and report back.

 

Changed the oil (Btw, Pep Boys has a sale on Fully Synthetic Peak oil for $4/qt.) and still heaar the noise.

However, upon futher testing, it sounds like a pulley... But then you would think I would hear it when I rev past 4K in neutral.. I'm at a loss.

 

That's just about when the EGR should be at maximum flow. If the EGR passages are plugged up, it will cause detonation under moderate load. (The EGR flow lowers the combustion temps and will prevent it from pinging.

The thing that doesn't make sense to me is, I'm assuming this is the DOHC Intech 5.4 engine, and it should have a knock sensor to keep it from knocking.

Also, pull the hose soff the DPFE and check to see that they are not carboned up.

Additionally, while the engine is at idle, force the EGR valve open and it should stall the engine if the EGR has sufficient flow.

 

I've tried applying a vaccum to the egr valve (I'm not sure which line leads directly into it as the EGR valve on my truck sits next to the firewall, behind the TB and Intake manifold. The two lines coming into the EGR vaccum solenoid, I've tried those and the truck did not bog down at all.

Also, the truck is slower than my wife's X3...

The knock sounds more like a rattle now..

I've got a new DFPE sensor in it, but checked it anyway. Clean as a whistle.

Yes, it's the 32V 5.4 DOHC.

Sounds like a EGR, EGR tube removal and clean eh?

 

Should be only one vacuum line connected to the EGR valve. Right at the top. Pull that vacuum line off the valve and apply your vacuum source directly to the top of the EGR valve.

 

That's the problem, I can't get to it because of it's location. On my 98 Expy, it's so accessible I can wrap both hands around it. On the 03 Nav, I can barley poke at it with a stick let alone take a pic of it based on where it is.

 

Oh, your right - upper intake is in the way.

So, lets improvise.

Pull that double vacuum line off the EGR regulator solenoid. Cover each of those vacuum lines (IIRC, one is a green line and one is a white line) with duct tape.

Start the engine. Uncover one of the liines - if 'n it is sucking, that's the supply line to the EGR regulator. Cover it back up before the engine stalls. The side that is not sucking is the supply line to the EGR valve itself. Apply your vacuum to this line. It should open the EGR valve and cause the idle to get very low or stall. If it stalls, or nearly so, that would confirm that the EGR passages are clear and flowing exhaust. The problem would then more than likely be in the control side of the EGR system.

After you cleared the codes, did the P0401 come back? Are there any other codes?

You said that your new DPFE is clean as a whistle. How about the two hose that connect to the DPFE? Are they clean/clear? And are they hooked up correctly? (One hose is larger diameter than the other hose.)

 

The white line coming off the EGR regulator didn't suck, so I tried both anyway. The engine did not bog down. I cleared the codes and after 10 minutes of driving, the P0401 came back.

The DPFE was clean and I even bought 2 new hoses (I cut to length from Ford) as well.

I'm thinking that if I have to pull all of this off to get to the back on the engine, this will be the last time I do it. Meaning, I'm pondering a EGR delete and have a "tune" programmer to delete the "EGR" all together in the ECU. Not to mention gain a few extra ponies and torque as well. i understand what the EGR is designed for, I just hate the fact that mine on the 03 Nav is sandwiched and could take over 1.5 hours before I can put a finger on it, let alone my hands....

On the 98 Expy, it will remain as it's in clear sight and is easily accessible. I'll take a pic tonight and will have to point to it with a stick. I tried taking a pic of it with my phone, but the firewall matting (insulation) hangs in the way of it a little.

 

Well, it could be the diaphram inside the EGR valve. Would the white line hold a vacuum or did it bleed right down?

But the EGR valve could be just fine and the passages inside the intake manifold could be coked up. How many miles on this beast? Has it been getting regular oil changes with the spec'd oil?

 

I think so as well. EIther EGR valve and or the Intake maifold ports as a mustang forum pointed out as well.

Sorry, I don't know. I didn't use a vacuum pump, I used a small hose and my lungs.

On El Chupacabra, 146K on the body, 88K+ on a rebuilt grooms engine. Since I've owned it beginning last May, only 5w/20 fully synthetic every 2800-3000 miles.

 

You may not be able to generate enough vacuum to open the EGR valve.

 

I'll swing by autozone today and see if I can use one of their vacuum pumps. Thanks! I'll report back with the findings.

 

Ok, being that in order to reach the EGR Valve, you have to take off the intake manifold, I decided to replace it all together.

To date:

The DPFE was clean and I even bought 2 new hoses (I cut to length from Ford) as well.
New EGR Valve
Cleaned out the intake manifold THOROUGHLY

Any thoughts?

I'm going to remove the lower section of the EGR tube where it connects to the exhaust manifold and check it out. Even snake the plumbing where the DPFE hoses connect to. If an elf pops out, I'm gonna choke him. LOL!