I have a 1996 E300 diesel. Two weeks ago I started the car normally and drove on the freeway, everything normal. At one point I felt a change in the way the engine was delivering power but the car continued to operate fine at freeway speeds. When I slowed down I found that the engine did not idle at exactly 700 rpm as it always did in the past, it slowed to less than 500 rpm, surged up to about 800 and finally settled down to 700. The engine idles rough compared to how it was before and sometimes the engine dies when at idle or when I put the car in gear.

Now when the car is stopped and I step on the accelerator the car lags several seconds before the engine starts to accelerate. It has so little power at low speeds that if I am on an incline, the car will not move at all and has even rolled backwards on me. Sometimes the engine dies when I try to accelerate from idle.

Once I get going and the rpm’s get up to 1,000 or so, the power kicks in and the engine is almost normal, it is able to accelerate to freeway speeds and runs just fine at 70 mph. I may feel a little roughness at speed but the engine runs fine.

The problem is less serious when I first start the car in the morning but after a while it gets so bad that the car is essentially undriveable. I will be sitting at a stop light, the light changes and it takes so long to get moving that the drivers behind me start honking and waving at me with one finger. Since once I get to about 15 mph the car is running fine and will accelerate and travel with the traffic, it really makes me look like an idiot.

I have cleaned the tank screen and changed the fuel filter. I looked at the air filter, it is nearly new and clean but I blew it out anyway. I removed the air intake crossover pipe that carries air from the air filter to the intake manifold. It is clear and the vacuum driven flapper valve is open. I made sure the flapper valve can move freely and put a little oil on it.

I have seen references in the forum to the ALDA. The 1996 car is normally aspirated, if it has that part could someone tell me what it is and where to look for it?

It seems to me like I used to see the vacuum cylinder and arm of the flapper valve on the crossover pipe move more or less continually when the car idled, now there is no movement at all. If I pinch the vacuum hose that is connected to the air filter box it does cause the flapper to move so the vacuum hoses appear to be all hooked up and since that does not happen if I don’t pinch the hose I am pretty sure the air flow through the air filter box is clear.

I removed the EGR pipe between the exhaust manifold. When I started the engine it ran the same. I removed the EGR unit, cleaned it, put a little light oil on the plunger and made sure it seems to move freely, all seems OK but I don’t know how to judge if EGR is working properly or not.

My “Check Engine” light is not on and no codes are showing up.

My mechanic and I have been messing with this for three weeks now and we can’t figure out what is wrong. Any ideas?

Don't have on of this model, so I am going by memory of reading other posts here (hint - do a search) that there are some intake manifold flow control flappers that can get either gummed up or somehow out of kilter, causing problems with air flow into the cylinders. I believe you have long and short runners and these flappers do something to make the air flow throught the correct ones. Just a guess, but I think if you search you will find more data. Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Jim;

Thanks. I have seen reference to the flappers and I removed the crossover pipe, made sure the only flapper I could find was moving freely and lubricated it lightly as I have seen referred to the in the older posts. Is that the part you are talking about or are there more flappers I should be looking for?

Thanks,
John

But consider changing the lift pump. Not too expensive. If the plastic fuel lines have not been changed in a while it would be good to do them as well. I was going to suggest the fuel filter, but you did that. My sluggish acceleration was fixed by a new fuel filter, and other running probs solved with the lift pump and new fuel lines.

Rgds,
Chris W.
'95 E300D

There are 3 flaps that I'm aware of: the EGR flap, the one in the middle of the crossover pipe, and one in the intake manifold where the crossover pipe connects. I would also closely inspect the engine for fuel leaks (around the IP and injectors). Another thought is the K40 relay which I had to replace because it was randomly shutting off my engine, but your symptoms are quite different so I'd try the easier and cheaper stuff first.

__________________
2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

John,
Man...I'd start at the beginning again with checking for fuel line leaks. Pull off the forward splash pans and see if you get any weeping on the ground after it sits overnight. The volume of air leaking into the system is a higher % at lower rpm/idle fuel delivery causing more noticible rough running. At higher rpm the volume of fuel being delivered is significantly more than the bit of air getting into the system so it may seem to be running OK at speed but it will still be leaking. You should be able to smell fuel when you pop the hood in the morning if the lines are weeping. It does not take much of a leak to through off low idle speed.
Good luck

__________________
FRED

Daily Driver: 98 E300TD 199K
Hobby Car: 69 Austin Mini
Past Diesels: 84 300SD, 312K
87 300SDL, 251K
94 Chev. K-1500 6.5Ltr.TD, 373K

I am still in trouble here. My mechanic took the car to our Mercedes Dealership, after three days they gave up and gave it back to him, although it turns out that they apparently don't have anybody there who really knows diesels. I have noticed what I thought was a fuel leakage problem in the past, when the tank is below 1/4 full and I park the car on an incline with the front end higher, the car is really hard to start in the morning. I always figured air was getting into the system somehow and letting fuel run back into the tank but my mechanic could never find any evidence of leakage and I never smelled raw fuel in the engine compartment. I will share the fuel line information with him again tomorrow and suggest that we replace the fuel lines.

Jwoos

I have exactly the same problem as what you have. See my post here:

http://www.peachparts.com/shopforum/showthread.php?t=153830

My engine is I think the same family as your engine. I have a 605 engine. I think you have a 606.

I have still not solved my problem and will be checking again for leaks although I did not find any.

I was suspecting the car starting on 2nd Gear and when on an incline could not downshift to 1st.

Another thing I though about is to try to put a bottle of diesel right before the IP and run the car uphill. This will isolate fuel line problems.


Just my 2 cents. Will keep watch on your thread. Hope you fix it!


Francis

__________________
94' C220D Euro (new 605 engine)
87' 250D Euro
02' E240 W211

Jwoos, have you or your mechanic removed the black, plastic cover from the top of the engine and inspected the injector lines and hoses? It's really easy to do and it's a good idea. If you're leaking fuel there, that might explain the hard starting and low power. The same applies to fuel leaks around the injection pump and fuel filter lines. Maybe this has been done already, but if not, that's where I would start! The intake manifold flaps are easy to clean and lubricate too and I would do that while I have the crossover pipe removed.

__________________
2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Sounds like air getting into the fuel system to me. Any air bubbles in the lines? My car had a similar problem. Air was getting into the system but I had only a very very slight fuel leak.

Until the car is fixed...you might want to drive something else. Having no power could be dangerous for driving.

It's a bit harder on the '96. I haven't done it, so I can't say how much time the intake pipe adds to the job.

Once you figure out how to remove and reinstall the crossover pipe, the second and subseqent times are easy and that's what I meant. Once you remove all the bolts (5 on the passenger side, 1 on the driver side) give the pipe a good whack from the front with a rubber mallet if it's stuck. To put it back, lube all the rubber seals, push the pipe coupling into the crossover pipe, attach the vacuum hose to the bottom of the pipe, then attach the pipe to the intake manifold (at the driver's side) and then at the passenger side. Tighten the driver's side bolt first, then do the 5 on the passenger side.

__________________
2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Guys;

Thanks for the comments. I am printing them all and taking them to the mechanic. I did remove the crossover pipe, made sure it was clear and that the flapper valve is working freely. I did not remove the plastic cover but I know my mechanic has been all over the injection system. He is telling me there is no "Lift pump" in this engine, that the fuel is moved from the tank to the engine by the "fuel distribution system". I think what he is saying is that the only fuel pump is the "vacuum" created by the injector pump. Does that sound right? Now they are speculating that I have a problem with the injector pump, they have to take it off and send it somewhere for overhaul.

I keep reading on the forum about similar problems caused by the EGR. I did take that off and clean it early in the process and I ran the engine with the EGR disconnected from the exhaust manifold and with the vacuum hose disconnected from the EGR. None of that made any difference. Is there anything I am missing that could cause this to still be an EGR problem?

Thanks!

I have now had the car to my regular mechanic, the Mercedes dealership and a mechanic that came highly recommended on this forum. Nobody can find the problem. The mechanic I found through this forum says the only thing to do is take the injector pump off and send it to an overhaul facility. He will ask them to check the pump before performing the overhaul, if the overhaul is done this is going to cost over $2,000. We did replace the fuel pump, I guess that is what people call a "lift pump" on the forum although the mechanic did not know that terminology. Had no impact. He also replaced all the fuel lines, again did not help.

Does anybody have any other thoughts?

Thanks,
John