E320 cdi Really annoying problem - please help anyone!!

[MACHBUFFET]

Hello guys
I've been on before with this problem but it still persists and is ruining my enjoyment of the car.
It's a 2006 E320cdi V6 with 85k and FMBSH.
The problem occurs only during the warm up period when the engine is 50 deg to about 70 deg. It doesn't happen when it's completely cold and when completely hot, only during warm up or if it's been parked for about 45mins and cooled for a while.
If I try to maintain a steady 950 rpm 1100 1300 or 1400 rpm, the engine sounds like it's misfiring and you can feel it through the car. This happens even if stationary and in park. Once warmed up, it's gone.
Have been to three indys now and to no avail. There aren't any fault codes stored at all. The last guy ran tests on the EGR and Turbo actuator and all came out fine. I've replaced the exhaust back pressure sensor with a new MB part and it still does it. Also replaced the turbo seal as a precaution and noted during removal that the area underneath was bone dry - no leaking evident.

I'm in Northern Ireland and have have visited the three known Indys here and no joy - if it's not a fault code they're stumped.
It happens every time during this temperature band.
I'm wondering if it's the Oxygen sensor?
I'm at my wits end with it and any advice would be greatly appreciated.
Thanks in advance

 

[Deleted member 37751]

That sounds like an air flow problem to me, but it's strange how it only does it at those temperatures.

 

[Merc Owner 2B]

Although I can't explain this I'm sure that a faulty O2 sensor would activate a fault code as it's easily detected.

I'm sure one of our more skilled members will be along later.

 

[mobeyone]

inlet shut off motor? could that cause this?

 

[BlackC55]

Blocked air filters or an o2 sensor maybe. Also check the injectors too on a star.

 

[MACHBUFFET]

Thanks guys.
The inlet motor showed no fault codes and was tested by the third indy this morning and found to be operating correctly, as was the egr and turbo actuator.
Acceleration and pull are great, no issues there.
There have been three smooth running checks on the injectors now and all well within tolerances.
O2 sensors likewise - no faults, although the indy explained to me that the management system may not log transient fault codes, would that be correct?One thing I have observed though, sometimes when this is happening, the static RPM rises to 850 rpm from its usual 720rpm.

This never affects the performance and acceleration, but only noticable from 950 - 1400rpm when maintaining a constant rpm.
Having had an E270 for three years that gave faultless performance, this is a heart breaker. I was expecting so much more from the V6, but so far it's been a bit of an anti climax. The expense is starting to add up as well, with an average of £40 a visit to be sent on my way none the wiser.
If anyone can help in any way at all, I would be hugely grateful.

Thanks in advance

 

[MACHBUFFET]

I've just been back through the service history print outs and noted the following.
Air filters replaced at 50,075 miles on 28/07/10

Fuel filter replaced at 49,243 miles on 09/11/09

Perhaps it could be time to rule out the basics and replace these, to rule them out.
FMBSH ????- surely this can't be recommended intervals?

Thanks again and if anyone has any more to offer, please let me know.

 

[Deleted member 37751]

In your shoes, I would do a full engine service (oil, air & fuel filters), certainly seems better than throwing £40 at someone to plug a computer in every other time.

When was it last serviced?

 

[AdamG]

Have you tried disabling the lockup clutch in the torque converter?

Also have you tried a leak off test on the injectors?

Adam

 

[MACHBUFFET]

Thanks fellas

Last serviced at 80250 by MB, using Mobil (same from day one) 85k now
Oil and filter service

Would the torque converter check be applicable here? The problem occurs even if the vehicle is parked up.

With the injector leak off test, would it require removal and bench testing each injector?

Most odd thing about this one is the specific relationship to engine temp.

Just wish I could get to the bottom of it.

 

[mobeyone]

Change both fuel and air filters as I understand both can cause problems when blocked.

 

[AdamG]

Sorry I didn't see that part about it happening even while stationary. Might still be worth disabling the clutch as it's very easy to do in star.


The leak off test should be done with the injectors still in the engine. Measuring bottles are connected to the injector fuel return line and the quantity 'leaked' back is measured.


This should be done at idle and at high revs.


I should say I have no idea if this has anything to do with your problem. I'm not familiar with this engine


All the best


Adam

 

[MACHBUFFET]

Quick Update

Have changed fuel and air filters today with genuine Mercedes parts. Unfortunately, there's very little change in the problem - still appearing like misfire between 950 - 1400 rpm (steady rpm maintained).
When I took out the fuel filter, I had good access to have a good look around the inlet port motor and I'm happy to say it's bone dry all around there, no evidence of and contamination. I replaced the seal as a precaution with a new one.
The air filters were absolutely choked and when I took them off and inspected them, I was sure that was the problem. Put it all back together and bo****ks! Still doing it!!!!!!!.
Still the filters were well over due for a change (despite FMBSH claim by MB main dealership)
I've included pics to show how bad. - Scrap that, doesn't want to upload for me for some reason, but they were in a shocking state.
Back to drawing board - bah
Help Meeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee!

 

[st4]

Sell it and buy a BMW. It will save you money and further problems.

 

[Dieselman]

It sounds like it's either over-fuelling or has too much recirculated exhaust gas.

 

[Black c320]

Its possible the fuel map is corrupt, a ECU reflash at the dealer or possibly a remap of the ECU may sort it out.

 

[gcarradice]

Hi, This problem sounds to me like a problem I have seen a few times, that is a torque convertor balance problem (out of balance ) but feels like a missfire, try a gearbox oil change & filter & adaptation reset & re adapt on star machine, it does help in some cases, but I have also changed a few torque convertors,
MBTech,

 

[MACHBUFFET]

I hear you ***!!
I was a dyed in the wool BMW man (still have my BMW 635CSI with me since 1999) having had a number of 7 series but took the plunge 3 years ago. E270 a pleasure, despite all the Valeo scaremongering, but this E320 V6 (FMBSH my a**e) isn't an enjoyable experience and the experience of the "support network of good independents" has been a wake up call.
MB Tech Warrington, despite the stretch of water between us, have been real gents and offered as much advice over the phone as they could, to try help, but there's only so much they can do from so far away. If any of you read this, please accept my thanks for your time.
Keep it coming guys, all guidance and benefit of your experience greatly appreciated.
Best regards
Barry

 

[MACHBUFFET]

Thanks gcarradice - much appreciated input.
In your experience, would the torque converter issue be to temperature related?

That's the quirky thing here - only in that specific temp band!!

What governing sensors are prone to temp fluctuations?????

Would an O2 sensor do this, without storing a fault code?

Does the engine have the equivalent of a choke????
During the funny spell, the idle rpm can hang at 850rpm (from 720) is this significant?

How does the throttle work? It's obviously "fly by wire" but is it possible that whatever signal is being sent from the throttle position sensor is corrupt?

Just trying to figure this lump out.

 

[Deleted member 37751]

Whereabouts in the country are you Barry?