I changed the fuel line from the heater to the pre-filter. That solved the air bubble issue but it still Idles rough. The interesting thing is that when the engine is cold it runs very soothly. Once it is up to normal temperature, it starts rocking and "missing". It smooths out again when either the transmission is placed in drive or reverse, and when the air conditioning is turned on.

The local dealer wants to sell me an IP pump but that doesn't make any sense to me because the car runs fine otherwise.It has plenty of power and accelerates nicely. Their mechanic also said that the '98 E300 does not have an adjustable rack screw.According to him it's electronically controlled. Is this so?

Does anyone know if the EC merely increase the fuel flow when the A/C is turned or the transmission is placed in drive, or does it increase the delivery pleasure in order to maintain the same RPM.

Nick

1998 E300 TD
160k

Do you know which cylinder is misfiring, or is it random? It sounds to me as though there isn't enough fuel, either because theres a problem with the fuel delivery, or because theres too much air getting in.

What happens when you increase the idle speed slightly?

I still think you should check the EGR valve, it is held by a spring which gets weak over time and the valve can sometimes not close properly. Carbon deposits also make this more likely. Intake manifold has to come off to gain access.

I'd also check around the EGR valve for any air leaks - mine has one at the base of the valve caused by an old o-ring I haven't gotten round to changing yet.

I don't know if or which cylinder misfiring or whether its random. I agree that there has to be a fuel delivery problem since all my problems started when I had the IP delivery O rings and seals replaced. I'm considering having the injectors tested.


When I increase the idle slightly, it still runs rough and it's noticeable until the RPMs are above approx 1500, unless, as I have mentioned before, the A/C compressor is running or the car is in drive.

I took it out for a drive this evening which included some hard acceleration. I was thinking how well it runs and then another problem popped up. It overheated and non of the electric windows close now. I think at the very least I have to replace the thermostat. What is really strange is that the windows won't close.

As for the EGR, I do notice some dark staining around from the cross under pipe from the turbo to the intake manifold. Next time I have the manifold off, I will take a closer look at the EGR.

Nick

1998 E300 TD
160k
Edit/Delete Message

Close with your finger on the button continuously, or close with the one-touch operation?

If the EGR is leaking you'll see oily deposits in the area surrounding it.

There is a pressure sensor mounted at the side of the manifold, it measures the pressure within the manifold - important for the ECU to know. The pipe comes from the EGR valve, and it is connected to the ECU via a small multipin connector. Check the vacuum hose for leaks/blockages, and clean the pins on the connector. You could also check the actuator which is on the other vacuum pipe to connect to the EGR. Interestingly, this actuator is identical to one that controls the turbo, which is situated directly underneath the air filter box. You could swap them over to see what happens.

I would guess that with the AC on, or the car in drive, more fuel is required and delivered - and thats why the misfire disappears.


Another thing that hasn't been mentioned is the MAF sensor. You could try giving it a clean:

http://mbclub.co.uk/forums/showthread.php?t=26286

http://mbca.cartama.net/showthread.php?t=19175&highlight=rough+idle+power

I knew I read somewhere how improper torque caused this condition on another car...I strongly suspect your tech didn't follow the torque procedure and probably didn't even use a torque wrench when they replaced the seals.

__________________
Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

This makes a lot of sense since my problem started when I the O rings and copper seals were replaced. I have read that the proper procedure for torquing is to tighten to 30 NM, wait, then 30 NM again, wait then final torque of 35 NM. Do you know if this is accurate info?

Thanks,

Nick

W210-025
1998 E300 TD
160k

That is one procedure, and another is just to torque them to 35nm once and leave them. When I did mine I did the 30-30-35 process and it worked fine and the car has been perfect since then (last december).

This is exactly why I don't ever let anyone touch my cars unless it is absolutely unavoidable. Many techs don't do things by the book and don't care if they screw something up, after all it isn't *their* car.

I'd bet you a buck that if you re-did the seals and torqued them correctly (either way but finishing at 35nm) you'd eliminate the problem.

__________________
Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

I'll let you know how things turn out.
(It might be a couple of weeks though since I have other things in life to tend to right now)

Thanks again,

Nick

W210-025
1998 E300 TD
160k

Parrot of Doom Wrote,"Close with your finger on the button continuously, or close with the one-touch operation"

Either way, window will not raise/close. They will open/roll down though.

Great link and pics on cleaning MAF. Thanks. Is there a link covering removal of intake manifold?

Appreciate the great info.

Nick

W210-025
1998 E300 TD
160k

If you look in the HOWTO section of that forum (it may be open only to members but joining is a 2 minute job) I have written a procedure on how to remove the manifold and clean the EGR.

As for the windows I suppose the first thing to try would be the 'reset procedure after disconnecting the battery', the details are outlined in your manual but from memory I believe you have to do something like hold each button down for about 10 seconds with the ignition in position 2.

This post (removing GP's) in the DYI Articles tab above explains how to pull the IM and shows the EGR, etc.

http://www.peachparts.com/Wikka/OM606962GlowPlug

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

As for the windows I suppose the first thing to try would be the 'reset procedure after disconnecting the battery', the details are outlined in your manual but from memory I believe you have to do something like hold each button down for about 10 seconds with the ignition in position 2.[/quote]

That was the problem with the windows; I had disconnected the battery and they needed to be reset. Funny how things are easy when you know how

Nick

W210-025
1998 E300 TD
160k

I’m cautiously optimistic that the rough idle problem has been solved. I took nhdoc’s advice since this seemed to make the most sense because the problem started after I had the IP seals replaced.

I checked the torque of the delivery valves. I was shocked by how much they were over torqued. Against my better judgment (I don’t always let that stop me) I decided to slightly loosen the delivery valves. I was hesitant because I wasn’t sure that the copper washer would re-seal after being crushed but I figured in a worse case scenario I would replace the seals and o rings again.(but I’d do it myself this time) Well, it took a lot of muscle on a long ratchet handle to break them loose. I re-tightened the seals to 35 NM and put everything back together.

After two days and about 100 miles, the rough idle is gone, regardless of weather the engine in under load or not. I don’t see any fuel seepage around the delivery valves yet. At first I thought the engine was “clacking” a bit louder that it used to, but that has quieted down a bit. I figure I’ll do a diesel purge on it to see if that quiets it any further but I’m so glad to see the rough idle gone.

Now I’m wondering why the wrong torque would effect the idle. Is it that over-torquing causes the plunger to bind somewhat. If this is the case it might explain why it does not idle rough when it’s cold. I’m assuming that when the engine is cold or under load, the EC adjusts the rack position to provide more fuel. This increased flow position can overcome any binding in the plunger, where a “normal” idle position of the rack, cannot.

My other theory is that over tightening puts too much of a pre-load of the delivery valve springs and increases the cracking pressure, which again, cannot be overcome at normal idle fuel pressure.

Either way, I hope this fix lasts. It’s a good feeling when a problem is solved and the car runs as it should. It would have been a lot more difficult to find the cause of this problem with out this board. All the dealers and techs that I have talked to have been of little help. The dealers tried to sell me an IP saying that it had no serviceable parts.

Thanks to all once again.

Nick

W210-025
1998 E300 TD
160k

Hi Nick,

Glad to have been of help...I'm sure you solved the problem. Overtorquing has caused this same condition before. While I am not 100% certain why it does I have heard that the entire IP body can warp ever so slightly causing the plungers to bind. The exact procedure you followed has cured others with the same symptoms but it is always good to have one more case to hang ones hat on. The clacking you hear after cracking open the fuel system is typical and most likely caused by air you introduced into the hard lines that had to work its way out...usually it does in a few miles driving but I have heard sometimes it can take longer...

In the words of Dr. House "everybody lies". That goes double for mechanics. They will swear on a stack of bibles they followed torquing procedures but almost never do. My lug bolts were so tight after I had my tires changed I had to stand on the end of the lug wrench and rock all my 200 lbs to break them free, after they swore they would torque them to the 95 ft-lbs spec. Yeah, right. I figure they were at least 200 ft-lbs.

__________________
Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Just wanted to add my solution to this thread on what ended my rough idle...
Same car as Nicks1 here - 1998 E300 TD. Approx 139k on the odo. Symptom: rough idle in park or neutral only after car warms up (hitting roughly 80 on the temp guage) While car was in drive, no problem on idle. And when car was cold (below 80 on the gauge), no problem) - (although it was a bit rough on deceleration around 10 mph also). Anyhow, here's what my journey was to the solution. Rough idle was not fixed until the final repair below..... read on.....
1. Motor mounts were new - just replaced per receipts before I bought the car.
2. I added several doses of diesel kleen to the tank and indulged myself with several italian tune ups.
3. Fuel lines checked for air bubbles several times - nothing
4. Fuel filters, air filter replaced
5. EGR valve checked, not failing
6. Fuel shutoff valve replaced (was leaking)
7. Coolant temp sensor replaced
8. Heat exchanger replaced
9. Probably something else here I'm forgetting. (cocktail impact here)
10. Injector pump - PROBLEM SOLVED

After the new pump was installed, it's smooth on deceleration and idle in neutral or any gear idle is silky smooth also. Just finished a 300 mile road trip and may have exceeded the speed limit by a few mph. You know, 58 or 59.

Hope this is info is helpful. And yes, the cost of the above repairs more or less went from cheapest to most pricey. But I love my E300.

__________________
Barker