The Check Engine Light on my '94 E320 Wagon (120K miles) is illuminated. I counted the number of pulses on the ECU to be 5. I understand from a previous post that indicates "Exhaust Gas Recirculation Inoperative." I cleared the ECU several times but the Check Engine relights about 40 miles later.

The car runs flawlessly, but the light is bugging me. I removed the EGR valve and applied vaccuum; valve opens and closes OK. No hissing from the valve when installed. Tube running from valve around the back of engine looks clear. What else can I check? Perhaps something on the intake manifold side?

Thanks,
Dave

Most of the time, I am finding that the end of the pipe that goes in just below the throttle body is clogged. I would start with cleaning it. I use an old speedo cable to roto-root it out.

EGR stuck?
 

I have a 91 - 300\e with an EGR acting up. What I do in the same situation (If the EGR is the same)is to spray a little bit of WD-40 and with the access to the shaft (careful with the diaphragm)move it a little bit with a flat screwdriver. That unsticks the EGR shaft and clears the problem. It has worked wioth me many times and I clear the problem every time.
Let us know.
AdamR
91-300E -164K

1) I removed the EGR valve and soaked the diaphragm shaft
with WD40.

2) Reference potential clogged EGR tube; I couldn't find a speedometer cable, so I used nylon monofilament line (approx 3MM dia) used on line grass trimmers. I fed the line from the valve side and hit what felt like an obstruction about 4 feet in, and worked throught it another 3 inches or so. I don't think I made it all the way through however. Getting to the tube from the other side is a bear from the top side, and not having a lift, nor the desire to take the top of the engine apart to get at it, I reinstalled the valve.

I cleared the fault, and a dozen trips and 100 miles later the check engine light remains off.

So...not really sure whether I cleared an obstruction, or just improved the EGR function with lubricant, but the problem appears to be solved.

Thanks much for your help!

I have just written an article for "Import Car" trade magazine. It is the cover article for February. In it I have pictures on this plugged port. I wish I knew how to post them here, but since I don't I would be glad to email them to anyone who can or would just like to see them.

Basically the passage that clogs is where the EGR pipe enters the intake (I also have a picture of where this is). In the article I also propose that we now do as a part of the 30K service the roto rooter activity suggested by Donnie. We have been doing this for a year now.

The reason for the clog isn't the carbon of the exhaust. It is a product of the PCV oil vapors of the lower intake manifold plating out on the hot inlet pipe.

Steve:
Maybe this could be posted as a DIY article by the webmaster. If for some reason this doesn't work, email me the pics and I will put them on my site so they can be posted.

Here are the Pictures Steve took of the work described above.



1) Engine Area under hood showing clogged Port in center.
Picture was taken from the drivers side looking down
over fender.

http://www.warewolf.net/jelliott/area.jpg


2) Close up of port, showing black clog in center.


http://www.warewolf.net/jelliott/clog.jpg


3) Close up of clean port


http://www.warewolf.net/jelliott/clear.jpg

[Edited by JCE on 01-22-2001 at 10:26 AM]

pictures
 

JCE et al,

The pictures seems to be unavailable. Could someone please email them to me :o. Thanks in advance...

ahc913@yahoo.com

I guess the fix worked only temporarily, since the problem resurfaced many times as you said.