E320 Cdi - PeachParts Mercedes-Benz Forum

rsl007 · #1 01-10-2004, 12:19 PM

The new MB E320 CDI will be available in April this year in the U.S. Any thoughts about the CDI engine. Should one wait to see how the engine runs here before ordering? Has it been a good reliable engine in Europe? I placed an order yesterday for one but am a little unsure whether I should have jumped so fast. Would appreciate any input.
rsl007

stevebfl · #2 01-10-2004, 12:29 PM

I have a number of customers who have been waiting for that car.

VW seems to have good results with their CDI engines. I see no reason MB won't.

73MB280SEL · #3 01-10-2004, 12:49 PM

Steve,

Does VW make CDI engines? I thought all of their Diesel engines in North America anyway were TDI. These are direct injection (no prechamber), but still retain a rotary pump. A true CDI engine would have a high pressure pump and electronic injectors.

I'm not that familiar with VW engines, so maybe I'm wrong. I do know that the new Duramax GM engine and Cummins Dodge engine are CDI and they are a VAST improvement over the older models.

Sholin

webcentre · #4 01-10-2004, 03:36 PM

this is a superb car here in europe. very very fast, as a comparison the estate version (wagon) is as fast as a bx16valve, which are not slow cars. extremly good engines, very nice.

stevebfl · #5 01-10-2004, 03:41 PM

Yes, TDI not CDI. Sorry.

pentoman · #6 01-10-2004, 04:41 PM

Yes VWs latest are PD - Pumpe Duse. Arguably superior to common rail CDI.

The 320 CDI's been succesful and reasonably problem free in Europe so far as I'm aware. Much loved by motoring magazine.

If you're still not convinced, perhaps knowing it's Mercedes' last straight-six car engine might change your mind? The 270CDi is the same with one cylinder less, and I believe the 220CDi the same with 2 cylinders less.

Note that being a straight six is the reason it's not found in the ML-class or C-class - it's too long! Did Mercedes shoot themselves in the foot?

engatwork · #7 01-10-2004, 05:07 PM

pentoman - is the 220 4 cylinder turbo charged too

?

73MB280SEL · #8 01-10-2004, 06:02 PM

pentoman,

I have heard this before but I don't understand the advantage that TDI would have over CDI. The one main advantage that CDI has over other forms of Diesel injection is that the injection pressure (and thus atomization) is not a function of engine RPM. In the old style with a pump driven off of the timing chain/belt, at low engine RPM, you do not have enough injection pressure to completely atomize the fuel. At idle, older mechanical injection systems atomize fuel very poorly and thus the familiar Diesel knock.

Having the injection pressure more precisely controlled is the same advantage that electronic ignition has over the points system. The spark plug voltage varies with RPM on a breaker points ignition system whereas electronic ignition always applies the same voltage of spark.

Another CDI advantage over mechanical fuel injection is the ability to perform a pilot injection, though most electronically controlled injection systems (CDI or not) now do this.

What is it about the TDI injection system that you think is better? My understanding is that rotary pumps are the cheapest, MB inline style pumps are the best of the mechanical injection systems, and CDI (electronic) injection systems are the best. Most Domestic manufacturers of non CDI engines are the rotary types, for instance, and they are not know for being very durable.

Sholin

pentoman · #9 01-10-2004, 07:09 PM

hey Sholin.

Sorry for any misunderstanding here - all the anacronyms are confusing!

I'm sure I've posted on this before but couldn't find it in the search so (don't worry, I enjoy it

).:

VWs old 90bhp and 110bhp (with variable vane turbo) units are TDis - mechanical pump.

Then they had TDI (PD) 115bhp. Now replaced with 100bhp and 130bhp units. Then 150bhp unit. All still 1.9l with 2 valves/cyl.

These are a high pressure system - like common rail (=CDI) - but without a common rail and instead using an ultra high pressure (30,000 psi) pump - Pump Duse or PD. (vs. 23,500 psi for common rail).

From http://www.tiscali.co.uk/motoring/roadtests/2002/05/03/story_1.html

"The turbo-diesel, direct-injection (TDi) engine is now quite familiar, but what about the PD bit? PD stands for 'Pumpe Duse' and translates as 'unit injector' - a device that supplants the old distribution pump as the source of back-pressure at the injector nozzle. In effect, PD injectors each have their own little cam-operated pump to produce even higher pressure (30,000 psi) than a common rail system, which uses a thin, tubular reservoir to contain pressurised fuel for feeding on demand to each of the injectors in turn.

The higher the pressure, the more effective and leaner becomes the upper-cylinder burn. Consequently unit injectors (PD) produce more power and torque for a given measure of fuel without cost to fuel consumption and CO2 emissions. As an example, the 130 bhp TDi PD engine in the test car, for the same 1.9 litres as the TDi unit it replaces, generates 13 per cent more power (130 bhp) and nine percent more torque yet returns an identical 52.3 mpg on the combined cycle.

The known facts are:

PD
+ More powerful

Common Rail
+ Quieter
+ Is catching up, though now on it's.. 3rd version?

To drive, I've only driven BMWs 320d 150bhp Common rail. It's quite petrol like, but in a way that actually makes the engine not that lovely. It needs revs somewhat and doesn't have the huge low-down kick that is the nicest feature of turbo diesels.

VWs PD's I've driven a number of. They have great low down punch from 1500 rpm, and don't drop off at high rpms like old TDs. Feel so superior to normal TDIs. And, rarely for a turbo diesel, very nice combined with an Automatic. Fast when fitted in a Golf.

Only VW develops PD (believing it is superior). Technically they are quite possibly right, but with more manufacturers backing common rail, they have competition.

N.B. all VW engines available in Audis too. A8 4.0 is the fastest diesel you can buy (275bhp, 0-60 6.7s, 155mph max limited). Oddly, this runs common rail not PD.

N.B. VW now has a 2.0 4 valves/cylinder PD. They haven't made a high output version yet, but it may replace the 1.9 TDi 150bhp as the highest specific output diesel available.

wow. that was long.

So in short, TD is elderly, no-longer with us and clearly inferior to modern PD and CDI systems.

Russ

73MB280SEL · #10 01-11-2004, 11:32 AM

Russ,

There you go, I learn something every day. Nice write up.

More injection pressure is better in terms of extracting power from Diesel fuel. I can see how minimizing the high pressure fuel rail length by putting the high pressure pump near the injector would be helpful. Ford (Fix or Repair Daily) had a cam driven injection system on their previous PowerStroke V8 Diesels, but I heard less than glowing things about it. Feedback I got was that if you weren't religious about oil changes, the cam fuel pump system would wear prematurely and cause a loss of injection pressure. This in turn would lead to "cackle" at idle and loss of power.

I'd also be curious as to how the VW PD system keeps the pressure constant over the injection period and constant with engine RPM. A cam system pushes the injection pump at a rate that is proportional to engine RPM. This is one of the advantages to the CDI system is that the pump squeezes fuel into a rail which has a fuel pressure regulator installed at the end. The fuel pressure regulator ensures that the design pressure is present in the rail at all times--it just bypasses whatever fuel the engine doesn't use.

I'm also curious as to how VW controls injection timing. The simplest method would be CDI: Since full pressure is available at all times, the millisecond you turn on the injector you have injection.

Wished there was a website showing these parts.

Thanks much,

webcentre (and pentoman), Tell me more about the E320CDI. What type of mileage are you seeing? I've heard 20 - 30% improvement over the gas version. What's the difference in get-up-and-go-ability from the 320D to the 220D. Driving a 190D 2.2 nonturbo 5 speed, I'm not too concerned about drag racing much. But, I think most people here in the U.S. would really prefer the larger engine. Gas and Diesel is pretty cheap here ($1.35 - 1.50/US gal).

Sholin

#11 01-11-2004, 11:40 AM

Gasoline in Europe is generally better quality than that in the U.S. and so is diesel fuel.

Common rail injection requires GOOD fuel. I'm not sure how the lower quality fuels in the U.S. will effect the rail injected MB diesels and gas cars coming to the U.S.

The last I heard it will be 2007 before low sulfer diesel fuels are available here.

Momo · #12 01-11-2004, 01:46 PM

As mentioned in another thread, if you talk to the taxi drivers about the new CDI engines, you get a different story. I have spoken to them in Helsinki, Stuttgart, Paris, Munich and Vienna. The new CDI E-class allegedly has major problems, even where the engine is nominally the same as in the previous model. The problems, in priority sequence seem to be:

1. Engine management electronics failures, some of which appear to have no known solutions.
2. Repeated turbo failures.
3. Catalytic converter leaks.

Recently in Brussels, a driver told me that the owner of his company at Zaventem airport had had so many problems with the late E-Class auto box that he had specially ordered a set of manual-boxed CDIs which he is registering this month. Not heard this one elsewhere.

General message from taxi drivers was "This is normal for any Benz in its first year of production." One of the Stuttgart drivers reminded me how they had barricaded the factory entrance with both the first E class and the origninal 190 models because of problems closing the doors.

Oh well.

Momo

rsl007 · #13 01-11-2004, 04:10 PM

My thanks to all those who replied to my query about the CDI engines. That is why this forum is so good..... you hear so many things that the dealers or salesman never tell you.... and probably in most cases the ordinary salesman has neither the interest or desire to learn about his products, at least in the depth that the members on this forum do.
I think I will hold off on getting the new E320CDI for a least a year to see how things work out. No sense plunking down $50,000 of hard earned money to get a problem that everyone else in the world knew of.
rsl007