Hi,

I'm new on here, have been told that you guys may be able to help me....


I own a Mercedes Vario 612D (2,9l 5 cylinder turbo diesel, 90kw), which has had some problems lately.



The truck is stuck in a limp home mode (or at least I think so) for most of the time. Sometimes it works normal, but most of the time has no power. For comparison, the up-hills that used to do with 4th gear now barely manages in 1st. It can't get past 2000 rpm, except in first gear. It appears that the truck works normal in somewhat colder mornings for longer period of time, before it goes to safe mode.

TEXA and delphi testers shows no errors at all.

Does anyone of you have any idea what could be wrong? The engine code is OM602.

The truck has new vacuum hoses, fuel lines and fuel filter.
EGR is also good.


Turbo solenoid? One of those sensors is probably the reason.... But which one?

Fuel injection pump is probably OK since the truck works normally 1/3rd of the time....



Thanks,


Mike
__________________

To be honest I'm surprised to hear there's a limp home mode on an OM602 - the technology of those engines is usually in the grey area of a mechanical system with electrickery interference added on top - usually for the idle control.

Looking on wikipedia (sorry knowledge base is that bad!) it seems to suggest you've got something that is essentially mechanically based. Working on the assumption that that's the case the first thing I would be doing is looking for air and fuel leaks.

Then I'd be considering the condition of the turbo.

Sorry I can't be of greater help (I have no experience of those engines in those big old barges)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Welcome to the mad house..........sorry, Mercedes forums.

What part of the globe are you ?

You might check here :

limp mode-can anyone please help? - Sprinter-Forum




.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

I've done that already...

No fuel leaks, I found a bad vacuum hose but I replaced it... Turbo is good, it does turn nicely and has close to none shaft play.

There is some electricity on those enginse, found a whole bunch of sensors (temp, boost, map,.....). One of those sensors is probably bad, I just wish I could determine which one....


Also, if there would be mechanical problem, I suspect the engine wouldn't run normally 1/3rd of the time...

Mad house is proper term....

In from Slovenia.

Say Hi to Jaka for me...he's in Ljubljana .( Jaka Bernardič )


.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

I've never heard of him, but I'd look him up if he can fix my truck.

I was just joking around 84. Jaka is an IT guy, was here a couple of months ago wanting to buy a 1956 190SL.

Did you check out the Sprinter link I sent you ?



.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

If it's like the older 60X engines, try to locate the boost sense port. These tend to become clogged with soot over time, and prevent the engine controls from adding fuel when the turbo is working. Without fuel, the turbo becomes a boat anchor, consuming power rather than adding to it.

Sounds like the "overboost" switch has tripped and hasn't reset itself. Like the post above says, look on the intake manifold for a couple of fittings screwed in the side. There should be a large "sensor" with a wire connected to it, and a "vacuum line" running to a switch somewhere in the engine bay. They both serve as part of the overboost circuit. If they get clogged up with soot, or one of the sensors fails, the primitive ECU will restrict fuel to prevent the turbo from spooling. Sounds very much like the symptoms you have.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Does this car have a vacuum controlled wastegate? 1990+ 2.5 Turbos and 1992+ 3.5 Turbos sold here absolutely have a limp mode where the computer will stop closing the wastegate... no boost.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I was just about to mention this.
Ditto here.

this would be my next move.


lookup "wastegate actuator swap"

__________________