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

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

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

I would think you could also find the offending cyl(s) by cracking each inj fuel line in turn and observing fluctuations in idle. The cyl that doesn't affect/affects idle the least, should be the problem.

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

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

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

Should I crack the fuel line at the IP or at the injector?

Nick

W210-025
1998 E300 TD
160k

IP is usually easier. Use a open end wrench and loosen them until fuel leaks out while observing idle quailty.

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

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