yes both 2005.

identical cars

You said you did the sensor on the back of the fuel rail. The one on the back of the fuel rail can not be changed it is set at the factory and the book says to change the whole rail if that is a problem. Mercedes does not change them at the dealerships just the rail. If you removed that sensor. I am willing to bet you got it in there good enough for it to run without an error code but not as good as the factory settings. It is adjustable maybe before you buy a new one for $325 you should micro adjust it. I think you should mark the rail in both directions and mount a pointer on the sensor. Adjust it left one notch and then test it. Adjust it right one notch. Until it runs really good. If it starts to throw code you know you did it wrong.

Good Luck with that.

I have purchased a new one and we actually swapped it out and it did not make a difference at initial diagnosis. It was a sensor at front of the hp pump.

From what I have heard, the press regulator is not adjustable.

Thanks

Do these cars have a fuel strainer in the tank that could be plugged?

Why do I ge the feeling that you guys are talking about two complete different things? HP pump and fuel rail...

The bio diesel has ruined your injectors I have seen this many times ... There is a tester for the leak quantity of the injectors if u want to confirm but pretty much garuntee they are ruined as well as the pressure regulator

After being away adventure travelling for almost a month, I returned home to Texas and once again have the pleasure of driving my 06 E320 CDI every day or so a few miles - it struck me that it is almost; overpowered, if anything. You have to watch that these massive-powered creatures don't get away from you when pushing the throttle on 'em. I am thinking that the foreign versions of the 05/06 E320 I6 CDI, the E270s, are probably a little more tame to handle and better mated for power, than these monster-powered 3.2 liter turbo sedans that we have here in the States.:)

Common Rail
 

Did you change the back of the Common Rail "We did the sensor at back of fuel rail." Because that would be bad. I was wrong I looked it up a new rail is $750. And Yes I have a spare in my garage that has an adjuster nut on it. It might not be adjustable but it can be adjusted.

Drove the car today. Running smooth and no smoke. Fuel pressure rail peaks at about 23000 psi..turbo peaking at 32 psi...

The dealer has flow tested the injectors before I bought the car..not sure if I can trust them or not..they also performed engine compression test. All seemed to be well

So if I am peaking at 23000 psi ..how could the pressure regulator at back of rail mis adjusted?

How can injectors be fried if car runs smooth and no smoke.


It seems like a software or sensor issue..but ..

If the injector spray pattern/atomization is messed up, I can see the results being low power and poor fuel economy due to poor combustion - it kinda makes sense. But then I would also expect there to be an observable difference in the way the engine runs - either idle noise, or perhaps additional black smoke under acceleration.

Unfortunately the piezo injectors are very expensive (~$500 each), so swapping them on speculation isn't feasible. I wonder if there are services which can test/evaluate/recondition them?

For not too much money you could dyno the car and have hard evidence of lack of power.

Rgds,
Chris W.
'95 E300D, 418K, not too much power, but enough

No Piezo injectors in the CDI, still won't be cheap tho

I am having a similar issue. When I first bought the car I was getting 32MPG in town. Over the last year or so the fuel economy has been slipping to the point now where I'm at around 26MPG for the same type driving. No codes in the computer according to ScanGage. Power has always been lower than it should be as indicated by the 9 plus second 0-60 time.

I keep track of the fuel economy on Fuelly.com so that helps in comparisons. Air, fuel filters, Glowplugs, thermostat(with temp sensor) have been changed. I cleaned the EGR valve, the MAF sensor, MAP sensor, and dielectrically greased most all electrical connectors under the hood in an attempt to maintain the vehicle and also to regain lost power & fuel economy. I even removed and reseated the fuses in the fuse box to ensure I didn't have any high resistance contacts there.

After reviewing the information online about how this injection control scheme works and the various sensor inputs I am wondering if I have a fuel temp sensor problem or perhaps an O2 sensor issue. Both those inputs help the vehicle decide how much fuel to use by way of adjusting fuel rail pressure and fuel injection duration. I am currently testing my fuel temp sensor which according to CDI literature should be a NTC(negative temp coefficient) type. Not sure what the resistance per temp spec on it is however.


I wonder if the OP has considered checking or replacing the fuel temp sensor or perhaps the O2(Lambda) sensor?

That's interesting. I have not had the car for long, in fact I have put less than 3K miles on it. My in town mpg's have always been around 26.5 to 28 and no more than 35 for highway, though I like to keep the go pedal on check to keep the EGR clean :P
I always thought the power was very good, but now I am starting to wonder if my car is suffering from the same and I just don't know better :confused:
I have no hard or soft codes either and the car runs as smooth as butter. I have read at least one member's comments about his car feeling like a "rocketship" and a "wild horse" that could easily slip out of control.
The only two cars I ever drove that gave me that particular feeling was a V10 Dodge Viper and a Porsche 911 turbo, and my CDI, although a very peppy car, doesn't even come close to that.
I hope my low mpg's are more related to my right foot rather than a motor related issue.
I'll be getting the bag of popcorn for this one...

Just a data point.... I purchased my 05 in 2010 with 130k on the clock. It now has 229k and 99% of those 99k miles were on homemade BD.

Mine still accelerates like a bat out of he** just like it did the day I got it. I won't even let my 16yr old son drive it because of the acceleration.

I recently had some shifting issues, so I sprung for the aftermarket tranny dipstick and did fluid and filter change. Back to normal health now.

During some of my shifting issues, it was evident that the tranny seems to have the ability to restrain the engine. You may want to look at the tranny as a contributor to your problem.

On BD, I will get 32mpg all day long. The very rare occasions of pump diesel, it will get 37.