Cleaned EGR Tube

[sunedog]

99 ML 320 with 207,000 miles. Had a CEL (P0400 code) for a couple of weeks. I took off my EGR tube and cleaned it out. It was solidly packed with black greasy gunk. There have been several threads on the subject, but none that really summed it up for me. Here was my experience:

I removed the air filter box lid, unscrewed the bolt holding the air filter snorkle to the engine and tried to open the funny looking arrow connector holding the snorkel in the back near the firewall. I tried pressng with fingertips and tugging and then resorted to prying with a screwdriver. It was 40 degrees at the time and the plastic broke. Oh well. Can't say I didn't expect it. Anyway, this allowed me to move the snorkel out of the way. It was only attached at this point by the wire to the MAF.

Used a 3/8" ratchet with a 2" extension and a socket (10mm?) to remove the two Torx bolts connecting the flange of the EGR tube to the rear of the intake manifold.

Used a small (about 8") Crescent wrench to loosen the large nut holding the other end of the EGR tube to the EGR valve. Then I could maneuver the EGR tube out of the rear of the intake manifold.

Went to the bench and was able to clean out the tube relatively easliy. The greasy crud was not very hard. I used a screwdriver and coat hanger to clean it out.

Tried at this point to remove the actual EGR valve. I was able to get the rear bolt out but could not get a socket securely on the front bolt because it is directly below the connector for a fuel injector and a rigid metal tube (which I think is a fuel rail). I tried with a universal adaptor and with a wobble adadptor but I couldn't get a bite on the Torx bolt and didn't want to risk rounding the corners over. Maybe a 12 point socket would work. I also tried to disconnect the connector to the fuel injector, but couldn't figure out which part of the connector to squeeze and which to pull on.

Any tips on removing this front bolt would be appreciated (for future reference).

I gave up and decided I would reinstall the tube, get the P0400 code cleared and see if the EGR tube was the only problem. I put everything back together and the snorkle seems reasonably securely positioned even with the broken arrow connector.

So far, so good. No CEL light and we'vew driven the truck 4 days since I cleared the code.

One other question: When I removed the EGR tube, I discovered a rubber connector directly below the intake manifold end of the EGR tube flange. This rubber connector had two tubes running into it and it seated in the intake manifold. One of the two tubes was disconnected. Don't know if I did that monkeying around with the EGR tube or whether it was already loose. What is that thing and could it have caused my P0400 code?