Can EGR valve effect idle?

[DieselCJ]

I am still trying to narrow down this intermittent idle situation (occurs about 30% of the time). Car shakes like a gasser at low idle with an agressive cam… I can see the hood and dash jumping, other times it is as smooth as silk. :puzzled:

Can the EGR valve have anything to do with it?

Thanks,
John

[RUN-EM]

Plug the vacuum line that activates the darn thing. It'll run better.

Regards

Run-em
1983 300 S D- aka.- SPARKY THE DIESEL

[KDHBenz]

Advise blocking not only the vacuum line but the EGR-intake manifold connection as well, thus completely disabling EGR. After having long since blocked the vacuum line to the EGR valve on mine, I finally got around to fashioning a functional if not perfect plate and sandwiched it between the EGR valve gasket and intake manifold...

Quotes from the MercedesList to possibly justify further action::

"On mine, the coupling hose on the air line to my EGR somehow got a BB stuck in it. Perhaps this weekend, the gasket between EGR and intake manifold may somehow be covered by a flat sheet of metal."

"You know how the vacuum connection on the EGR valve can get clogged up by a BB? Well, you would think that this would render the EGR inoperable, right? Wrong -- at least on a 603. When I opened up my intake area where the EGR "exhausts" the exhaust back into the intake, there was a nice "curved" trail of oil from the EGR's output, and fresh at that. I'm assuming that the curved path is indicative of the air swirl as a result of boost. Given this trail of fresh EGR output, it appears that further steps may be needed besides the "BB" fix."

Both experiences from seasoned diesel-heads...good enough for me...



-Ken
1984 300SD

[boneheaddoctor]

Originally Posted by DieselCJ

I am still trying to narrow down this intermittent idle situation (occurs about 30% of the time). Car shakes like a gasser at low idle with an agressive cam… I can see the hood and dash jumping, other times it is as smooth as silk. :puzzled:

Can the EGR valve have anything to do with it?

Thanks,
John

Does the 190D Injector Pump have a rack damper on it? If you had a OM617 thats the first thing I would have looked at for that symptom.

[Pete Burton]

a partially stuck open EGR will cause rough idling.

[DieselCJ]

Originally Posted by boneheaddoctor

Does the 190D Injector Pump have a rack damper on it? If you had a OM617 thats the first thing I would have looked at for that symptom.

About a month ago I searched, and searched to find that the 602 does not have the rack damper bolt, which was the solution to many other rough idle problems in the 617's.

-John

[boneheaddoctor]

Originally Posted by DieselCJ

About a month ago I searched, and searched to find that the 602 does not have the rack damper bolt, which was the solution to many other rough idle problems in the 617's.

-John

I've never seen the newer IP's and thats why I asked....

[Hatterasguy]

Well his 602 looks a lot like my 603 with one cylinder chopped off.

So I will go out on a limb here:

My 603 will rock the car everyonce in awhile. Usually if I bring the rpm's up the problem will go away. I just live with it for now. I talked to a Bosch shop about it and they said something in the IP could be getting weak and to turn up the idle. I turned the idle up and it worked now it only does it about half as much.

Afaik the only fix is an IP rebuild and I am not going to do that at this time.

[DieselCJ]

Originally Posted by Hatterasguy

Well his 602 looks a lot like my 603 with one cylinder chopped off.

So I will go out on a limb here:

My 603 will rock the car everyonce in awhile. Usually if I bring the rpm's up the problem will go away. I just live with it for now. I talked to a Bosch shop about it and they said something in the IP could be getting weak and to turn up the idle. I turned the idle up and it worked now it only does it about half as much.

Afaik the only fix is an IP rebuild and I am not going to do that at this time.

What intrigues me is how sometimes it runs very smoothly, which could suggest it is some sort of engine control malfunctioning part of the time. I would like to know more about the circular unit on the back of the IP (with a wire connected to it); wondering if that has anything to do with it.

Thanks,
John