John - I would look at the obvious things first, like injectors. I had all
of mine in the SD taken out, checked for spray pattern and calibrated. My
indy did me a "favor" by replacing one that had a leak, and that made the
engine idle pretty rough, hence the calibration. Runs a lot better now.
I'm thinking that injectors working at different pressures, and with perhaps
something in the lines causing a bit of flow restriction would give those
symptoms. You could start by just cracking the lines at the injector while
idling, to see if that changes the smoothness. You haven't changed filters
lately in that car, have you?
Of course, with that much newer engine than my 617, I suppose that there
could be some exotic stuff going on....
Werner
----- Original Message -----
From: "John W. Reames III" <[EMAIL PROTECTED]>
To: <mercedes@okiebenz.com>
Sent: Wednesday, January 24, 2007 4:45 PM
Subject: [MBZ] E300Dt question
I have two, so I can a-b them. Anyhow, One of them has a "stumbling" issue
at highway speeds; I'm suspecting EGR issues, whether its a sticking valve
or pressure converter (there is also a pressure converter for the
wastegate...). It also runs rough with no load, like an occasional miss.
This also leads me to suspect the EGR (sticking open?)
I have noticed the fuel mileage is "off" (down by 10-15%) from before this
began. I had wondered if it was the fuel change, but with a second car
doing the same drive on the same fuel turning the "better" mileage, I'm
pretty sure it is not the fuel.
The trip is 97mi one way, mostly highway driving, so its not a short-trip
or small sample statistic ;)
I seem to think that the OM606.962 is a "open loop" emissions system (no
sensors on the exhaust, but an air mass meter and electronically controled
wastegate/injection pump).
Anyhow, how should I go about troubleshooting this issue? I suppose I
could swap the pressure converters between the cars and see if the issue
disappears (swapping them within the same car did nothing, but I hear
they can both go bad at about the same time.)
The pressure converters are about $100/ea and the EGR is about $400
(mixing housing with integrated EGR).
Does anyone have access to the engine troubleshooting manual (EGR stuff)
that might shed some light on this?
Thanks
-j.
--
1985 300D
1991 Jeep Cherokee
1999 E300Dt (x2)
