<TABLE id=post1652049 class=tborder border=0 cellSpacing=0 cellPadding=6 width="100%" align=center itxtNodeId="406" itxtHarvested="0"><TBODY itxtNodeId="407" itxtHarvested="0"><TR vAlign=top itxtNodeId="409" itxtHarvested="0"><TD style="BORDER-RIGHT: #ffffff 1px solid" id=td_post_1652049 class=alt1 itxtNodeId="419" itxtHarvested="0">Hello, I am chasing a P0402 EGR Excessive code. I tested the DPFE sensor as bad and replaced it, with no change ( May have used the wrong test spec's, sensor may have been good. ). I got angry and just through a EGR control vale at it , with no change. And I believe the EGR valve itself is able to go from full closed to full open via vacuum testing. So now as I am trying to put together a list of all other items that I need to test/ID to isolate/correct this fault. To the best of my understanding, the only other things left in this system are the: 1.)two EGR tubes from the exhaust manifold up to the DPFE sensor, 2.) The wiring to an from the two sensors and the ECU/ECM. 3.) The ECU/ECM. Am I missing something?????? I want to rule out items 2 & 3, Question?how can I simulate for the DPFE sensor inputs, the correct manifold pressure for a full warm cycle engine at idle condition? I'm sorry, I have gotten ahead of myself here... the car is a 97 sable 3.0 duratec/DOHC, with 56,000 mile. I am pulling only one code P0402. Excessive EGR Flow. My drivability issue(s) that I notice are, only rough idle after full warm up cycle. Good idle at cold start. I am getting what I think is full vacuum at the EGR vale at warm (rough) idle. I can pull the vacuum line at the EGR valve with ( rough) idle and she'll smooooth right out. Put the vacuum back, and stumble to stall. I am getting cranky, and could use any help y'all have to offer.

Thanks.

Oz.

 

Do you have vacuum at the EGR valve at idle? if you do then the EGR selonoid is bad

 

Yup, i do have vaccum to the EGR valve at idle. I just today replaced the EGR selonoid, with the same trouble.

 

Can you blow air through the solenoid with key off? is module sending voltage to it when it shoudnt be at idle?

 

It pays to understand what the 402 test is.
The PCM sets up a test to see if the hardware is tight and not leaking.
The PCM tests for pressure between the exhaust manifiold and the 'closed' EGR.
If there is vacuum at the EGR to open it when it's not supposed to be there, the DPFE will not measure the pressure the PCM expects to be reported to it, for compairison to a table.
If any part of the metal EGR hardware is cracked or rusted through, the same result is seen by the DPFE.
In the metal tube is an orfice the DPFE measures pressure drop accross in order to test for a flow fault. If it's plugged only one side of the DPFE sees the exhaust pressure.
The EGR vacuum regulator is a 3 port device.
Meaning it has a vacuum inlet from the intake manifold, an outlet to the EGR, and an open port internal to the body that lets filtered air in [for the release of the EGR once it was opened] and the regulator is released to close off vacuum.
If your engine smooths out after you remove the vacuum line to the EGR, the EGR was being held open by vacuum.
This is a fault and will result in a 402 code no matter the reason.
The second part of the effects of this is ***** the EGR lets exhaust gas into the intake and causes the rough idle. The ignition timing changes and the fuel is cut back. All these action causes the rough idle but is transparent to the driver when at cruise on the road when it is supposed to work.
Your right on top of the trouble. Just find it.
Good luck.

 

Messed with it a bit tonight, Don't want to say much, got to run it through a few more drive cycles to see.

 

......Alright, I Got It !.... ....... I troubleshoot Telecommunication equipment for a living, so I love the challenge of fault isolation and how hardware and software interact with each other to work flawlessly, or work to create a trouble worth sinking your teeth into. Add a " Special " end user into the equation, along with manufacture bugged software, and then it really starts to get fun. You all led a fellow technician through a foreign land..... .....Thank You.... .....................Here it is...... The Manifold vacuum and EGR vacuum lines had been reversed at the EGR control valve...........( not something that happens easily) Now, I know how this happened. First I will say that I am 4dsomething and have lived my On The Job Training with the learn while you burn philosophy. That's to say,try it, if it works, your the hero, If I not you own it !!!! The vehicle went to a local shop about two months ago for a P0303, He gave it back to me, saying he couldn’t figure out what was causing the #3 misfire. it came back with the 0303 and the 0402 code. I shot the P0303 down to a bad coil pack, but to pass inspection it also needed front calipers,disks, pads, and now the 402 code. At the time I just didn’t have the cash, and tabled the project for a while. The Good News is, It passed inspection today. The owner of the shop was not in today, so I told the inspection tech that I would be back to "pay his boss in full tomorrow". So the only question I have for him is, ( his response is not required ) Was it a simple shop mix up ? (***** happens), or Were you trying to roll me on an easy EGR repair ??????? .......I know my rant sounds like that of a irate customer, but its not. I myself am a service provider, and have been for my entire professional career. One who holds himself to a standard...... Anyway, This site is cool, and the people are great. Again, Thank You.

Sable_Oz
AKA: ElCamin_Oz
AKA: F150_Oz

 

Great outcome.
Good luck.