W210 Acceleration Problem - PeachParts Mercedes-Benz Forum

muleears · #1 08-13-2007, 01:29 PM

My 98 210 is generally a great running car but under moderatly hard to hard acceleration it wants to surge and not accelerate in a linear fashion, it almost feels like it is shifting more times than it actually is.

First thing I thought of was fuel filters, changed both and the air filter also. No difference. Cleaned the MAF, maybe a slight improvement. The car still accelerates very well. I am only off the 0-60 by about 1.5sec. But I would like to get rid of the surging.

What else could it be?

Maybe an air leak? The car has no known leaks of any fluids.

nhdoc · #2 08-13-2007, 03:01 PM

Quote:

Originally Posted by muleears

My 98 210 is generally a great running car but under moderatly hard to hard acceleration it wants to surge and not accelerate in a linear fashion, it almost feels like it is shifting more times than it actually is.

First thing I thought of was fuel filters, changed both and the air filter also. No difference. Cleaned the MAF, maybe a slight improvement. The car still accelerates very well. I am only off the 0-60 by about 1.5sec. But I would like to get rid of the surging.

What else could it be?

Maybe an air leak? The car has no known leaks of any fluids.

Are you sure this isn't just the typical turbo lag/surge that they all have or is this something new for you in this car that it never did before? Usually mine will not really start to kick in until 2000-2500 RPM then what feels like a surge in power is really just the turbo boost functioning (normally).

F18 · #3 08-13-2007, 03:58 PM

Muleears....welcome to the 98 w210 club! Just as nhdoc mention it sounds like the typical acceleration of our diesels with turbo lag finally catching up at
2K to 2.5K rpm. The more familiar you get with this car you will learn to anticipate earlier when you need to pass or merge onto the highway. Sometimes it seems you could take a sip of your coffee and put it down in the holder before the car makes its move and really accelerates....and all you can do is grab your "lucky stones" and hope.

Outside of what you have already replaced,....fuel and air filters there is nothing else that could really be causing sluggish acceleration without throwing a CEL or defective alert on your dash or an OBDII code that would signal a problem.

F18 · #4 08-13-2007, 04:15 PM

Muleears....just an after thought. They have been able to successfully chip our 606.96 engine to alter the torque and horsepower curve to get the rpm up earlier and the turbo spooled up faster with less lag. There are some companies here in the US that do it.....but you would have to do some searching. I read the UK publication "Diesel Car" and they have been chipping this engine for years over in the UK and Europe.

Also check your intercooler hoses for leaks or lose clamps....the leak could be causing addition turbo lag.... and you can sometimes hear those leaks.

muleears · #5 08-13-2007, 08:28 PM

Thanks for the help so far guys, but I don't think it is turbo lag. This is my third turbodiesel (but my first 210) so I am familiar with the lag. This will accelerate irregularly whenever above 3K RPM, at which point I would think boost should be relatively stable.

But nothing is causing a CEL. I understand there could still be some codes stored so I will get them read ASAP.

aklim · #6 08-13-2007, 11:19 PM

Injectors? Wifey said acceleration improved after I had them cleaned. I didn't tell her what I did. There was 1 bad injector with bad spray pattern and low pop off pressure that was fixed in the cleaning.

Besides, it couldn't hurt and I did it at 120K

Maybe also the hoses are leaking? It might surge when it gets the air out of the hoses.

What about your timing? I know at 60K, my chain stretched out some and we had it set back to where it should be but I can't remember the results.

May not be right at all but just tossing ideas out.

muleears · #7 08-14-2007, 05:00 AM

Aklim, those are some excellent suggestions. The car is new to me and unfortunately I have no service records. It was sold as part of a divorce settlement and the wife had burned all the records! The only things I know have been done are at least one clear fuel line was replaced. I have changed all the filters and fluids (except brake fluid and charcoal cabin filter), recharged the ac and had an inner tie rod end replaced.

Regarding the injectors, I think I will try a diesel purge, I have nothing to loose other than about $15. I have to take the car on a 1K trip this weekend so I don't think I can do anything else with the injectors before then. Do you suggest removal and cleaning with acetone or have it professionally done (including a pop test)?

Parrot of Doom · #8 08-14-2007, 05:33 AM

The car has two vacuum devices, one for the turbo and one for the EGR. They're identical part numbers. One is under the airbox, the other is near the fuel pump. A black cylinder with 3 pipes.

Each controls the turbo and EGR valve. You should consider checking the quality of the piping to each, see there are no leaks or blockages, and as a little experiment try swapping them over (they're identical remember). Check the air filters to each (at the end of one of the pipes) are in good order.

I'd also check the ATF level since low levels can show similar problems, albeit only when cold and in low gears.

There is a bit of turbo lag but not a lot - its quite progressive on this car, you shouldn't really feel it in anything other than 1st gear.

nhdoc · #9 08-14-2007, 07:28 AM

Fuel lines are an excellent place to start. You mentioned replacing filters but did you also replace the pre-filter's o-ring seal? That can let air into the system if it is leaky. Check for air bubbles in the lines and if they are too dark to see into they should all be replaced. You'll need to pull the intake manifold off to get one of the hoses out. If you do pull the intake clean it out as it may be clogged up and check the EGR for crud too.

Since you have no history of or with this car I'd suggest trying the purge out and just drive it hard for a couple of months. I've posted many times that these cars like to be driven hard and if they are babied it can result in poor performance and bad fuel economy (you didn't mention what kind of mileage you are getting...is it in the high 20s?). As things get cleaned out you will see improvements in both performance and economy.

When I first got mine at 115K it was doggy and got 24-26 MPG. The first time I redlined it I had blew out a cloud of soot that I thought must have destroyed something in the engine, but no, it was just what had been accumulated after being babied for years. Now, after I have put about 40K more aggresive miles on it I get 27-32 MPG and the car runs like new.

aklim · #10 08-14-2007, 09:36 AM

Quote:

Originally Posted by muleears

Aklim, those are some excellent suggestions. The car is new to me and unfortunately I have no service records. It was sold as part of a divorce settlement and the wife had burned all the records! The only things I know have been done are at least one clear fuel line was replaced. I have changed all the filters and fluids (except brake fluid and charcoal cabin filter), recharged the ac and had an inner tie rod end replaced.

Regarding the injectors, I think I will try a diesel purge, I have nothing to loose other than about $15. I have to take the car on a 1K trip this weekend so I don't think I can do anything else with the injectors before then. Do you suggest removal and cleaning with acetone or have it professionally done (including a pop test)?

Did you check MB? They might have records too. You change one line and you disturb others. In any case, the lines might already be leaking but you don't know it.

It cost me $70 to have 6 injectors tested, 1 cleaned and retested. This way I KNOW that it is right. What will you have with Double Penetration? A SWAG at best. If you are going to take it out, you are going to have to get a fresh return line and cut it to length, 1 terminator and 6 bushings. Plus, you are probably going to disturb some of the clear fuel lines. Why not just send it to be tested professionally? That way if they come back clean, you can rule out injectors as a problem cause.

Another thing. Your crankcase vents into the turbo. That puts an oily mist into the intake. When it meets the EGR, what do you think happens? I'll tell you. Goop forms in the runners. There was a client at the local MB shop that swore the car never ran so good. What did they do? clean up the coked up crud in the intakes. That could be part of your problem too. Just occurred to me.

Here is my suggestion. Take off the manifold and hit the GPs. Take them out and CAREFULLY. Put Anti-seize on the threads. While you are there, clean out the runners in the head with a rag soaked with brake cleaner or gasoline. Take out the injectors and pre-chambers for cleaning. Clean the manifold too. Been there, done that and car runs well. I don't have the pre-chamber tool but I have the special tool to remove the injectors and for the price of shipping, you can borrow it.

aklim · #11 08-14-2007, 09:38 AM

Quote:

Originally Posted by Parrot of Doom

I'd also check the ATF level since low levels can show similar problems, albeit only when cold and in low gears.

That, BTW, requires a trip to the dealership. It requires you to hook up SDS to the car and a dipstick which our cars don't have.

If you are keeping the car, I would change the fluid. First time I did it at 60K, the fluid was not burnt but darker than it should be. Just did it again and it is ok. I do it every 60K irrespective of what MB claims about the lifetime fill.

muleears · #12 08-14-2007, 11:55 AM

Parrot, will try your suggestion this evening, time permitting.

NHDOC, Replaced the O ring also, haven't been through a full tank yet to check mileage, will get that done this weekend.

Aklim, no knowledge of prior tranny fluid change, that is being done today. Injectors will have to wait till after the trip.

TMAllison · #13 08-14-2007, 12:13 PM

Cal - You are aware the trans requires one of two MB syn fluids, right?

You can use the orig product spec'd for the 722.6 or the new fluid used in the 722.9. The newer fluid is a tad cheaper.

aklim · #14 08-14-2007, 12:45 PM

Quote:

Originally Posted by muleears

Aklim, no knowledge of prior tranny fluid change, that is being done today. Injectors will have to wait till after the trip.

To get the fluid level right, you are going to need Star Diagnostic System or SDS hooked up. It will give you the temp at that point and they have the fluid dipstick to check it. I wouldn't take it to Quicky Lube.

muleears · #15 08-14-2007, 05:54 PM

TM; Used the MB fluid for the 722.6, thanks for reminding me. Indy knew to check it with the dipstick tool at 80*C so I guess its ok.

Took it to Advance Auto on the way home to get the codes read and guess what...no codes found! I guess I'll keep trying other things you all have suggested