CDI Fueling issues (still) Mercedes can't help.

[Cnics]

The fault appeared mid December, and the van has been off the road since.

To recap. Massive overfueling when the engine is cold (Diesel knock, black smoke, EDC light and fuel cut if you don't back off straight away). Clears itself up in a few miles and runs perfectly thereafter until it's stood overnight. Sometimes needs standing longer. Ambient temp is 10 degrees higher now than it was when it first did it and the problem still exists.

Changed :

Waste Gate Sensor.
Turbo Boost Sensor
Turbo (though it was leaking and changed for that reason mainly)
Fuel Rail Pressure sensor (on the front of the rail)
Other Fuel Sensor (on the back of the rail)
Injectors 4000 miles ago (brand new sealed, the right ones)

Vacuum is ok, Fuel pressure is 360Bar on tickover, reaches a maximum of 1400Bar (is this normal?)

Readings from ALL other sensors are within tolerances when the vehicle runs normally and when it acts up.

Fuel lines clean.

Pump checks out ok (though it's not been off).

All wiring looms and connections checked.

Starts in half a second without any problems.


Costing me £50 per day in van hire now i'm back working again (January and part of Feb is always quiet).

Indie is stuck, Local Merc Dealer has been over and looked and hooked it up and can't find a fault. EVEN when it performs it's little trick, no fault found.

I'm completely lost on this one. Thanks for the advice so far to everyone that's helped, i've passed it on and it's ALL been checked but sadly not cured the problem.


Rob

 

[television]

Just bringing this to the top of the pile

 

[djb]

so far you have worked on the fuel side , more fuel = black smoke


how about less air = black smoke
gunged air filter?
gunge blocked intercooler
induction plumbing with delaminated wall?
valve clearance too tight.
really fishing now
loose bit in induction tract that changes shape to clear passage when warm?

 

[Cnics]

Air filter was new at last service which was at the same time as the injectors were done (about 4k ago).

It's a 2 year old (though 70,000 miles) Intercooler. But that doesn't stop anything.

My knowledge is extremely limited but i was under the impression that less air due to the above couple of things would lose power not gain lots of power.

Could something such as oil be settling somewhere it shouldn't normally be, or shouldn't be in quantity and somehow due to some underlying problem the van when boosting is being fed from oil? until there isn't any left in the place it is settling?
I have no idea what interacts with what on the air/oil side of things but i do know that the intercooler pipes get a bit clogged up with oil. And i know oil burns well.

Rob

 

[djb]

oil always burns with blue smoke,usually lots of it as well!

 

[Cnics]

There is lots of smoke, but it is black.
I guess i don't allow it to smoke too much as i always back off if it starts doing it so it's just a little bit of smoke from the back, but it's ALOT for a little knock and rattle. If i keep my foot down no doubt it would cover the road in the few seconds before it cuts the fuel off and the EDC light rears it's ugly head.

 

[djb]

If you take it to the black smoke point then backoff, then reapply, does the smoke return with the same power or not smoke, or smoke with less power?


has anybody looked for an exhaust blockage cat or loose baffle etc?

 

[Cnics]

Black smoke point, backoff, reapply it does the same thing. Lots of power same smoke.

It's just had a complete exhaust system on it. It was the original and i wanted it replacing when the fault had been cured. However, one sensor was put on and it went away for a couple of days so he put the exhaust on, but then it came back again. There is no cat, i believe that was taken off before i owned the van (i bought it at 2years).

 

[GCLTuning]

This is a long shoot but is sounds a bit like a mapped fuel table with out changing boost values ie Black smoke and faults


Has the vehicle ever had a Remap ?

Has the vehicle had a software upgrade from MB ? Ie recall ECT

Regards Gary @ GCL Tuning

 

[Number_Cruncher]

Is the EGR sticking?

 

[Cnics]

The EGR sensor is being changed, half for the sake of it, half as we're running out of sub 4 figure options.

Gary, would that be a possibility if it only did it from a cold engine. At first i thought it might be freezing temperatures, but since its warmed up 10 degrees i think it is just what we call a cold engine, ie ambient temperature.

I think the fault would be an easier find if it did it all the time, not just for the first 1/2 mile to 6 or 7 miles depending upon its mood.

So to answer your questions directly. No the engine has never had a remap since I owned it and i bought it at just over 2 years old*. It felt like any other 311.
Again, no software upgrade/update from MB since i've owned the vehicle. It was sold without service history.

* I did run it with one of the so called better chips on it for a short while that belonged to a friend to see what it did to the van. It worked, but at the cost of fuel consumption. I did maybe 2500 miles with it on then took it off again. But this was 6 months after i bought it so over 3 years ago.

 

[Cnics]

Shameless bump to see if anyone else has any ideas about this one. Getting desperate.

 

[djb]

this is a long shot.This thought comes from the fact a lot of power boost systems alter the percieved temp to increase fuel quantity delivered, & thus power.

could a engine temp sensor give occasional false too low readings? either by sensor failure or damp/corrosion on appropriate plug contacts thus convicing the fuel map more fuel required.

 

[Blakey]

My first thoughts when reading this thread were faulty temperature sensor.

 

[Hertfordshire Merx]

If there are no faults on Star current or stored in CDI then its something either not checked by the control unit, the control unit itself or there is a problem with another system on the van.

Out of interest what doe the outside temperature sensor read, can you please let me know if its accurate first thing in the morning. The value is put on the CAN network and distributed to various control units to use and make adjustments. If the sensor is way out or on its emergency setting of approx -35 degrees C, then you will have overfuelling issues. Would be interested to know what its doing.

 

[Cnics]

Thanks for all the info, i'll get in touch with the guy about the temp sensor.

So, am i right in thinking that that little temp sensor on the front of my van (that doesn't work) controls and gives data to lots more things than just the little temp reading on the dashboard?

My local dealer told me that all that sensor did was tell me the outside temp. Nothing else. Was he wrong?

This sensor doesn't work and hasn't for aslong as i've known that it was there.


Rob

 

[Hertfordshire Merx]

Yes you're right, the sensor sends the ambient temperature reading onto the electrical system known as the CAN network (Controller Area Network) and is distributed round to various control units. The control units which are programmed to accept the data from it make use of it as a control field.

In the case of this reading it will have an effect on the engine for cold start reasons, air conditioning to regulate the cabin temperature etc etc. Would have been the first thing to change and go from there...

SLK's suffer with this a lot and can cause horrendous running problems.

 

[Cnics]

I've got contradicting information here. The guy assures me that there is a temp sensor on the turbo boost sensor which monitors the actual intake temp rather than the ambient temp and that one on the front plays no part in the engine management.

I can say that i shall be somewhat annoyed if he's put on 5 sensors, and spent 20 hours on it, and had it since the 5th Jan for a £3 temperature sensor.

I'll post back when i have more news.

Rob

 

[Cnics]

Mercedes say there is no more they can do.

To quote : "effectively, it's scrap"

So i'm lost.

Anyone want to buy a sprinter that works perfectly as long as you don't leave it stood more than a couple of days???

 

[djb]

Mercedes say there is no more they can do.

To quote : "effectively, it's scrap"

So i'm lost.

Anyone want to buy a sprinter that works perfectly as long as you don't leave it stood more than a couple of days???

I woud suggest they get an engineer from m keynes up to look at it, and if they are not keen suggest honest john of the daily telegraph might hear about the sorry tale. even suggest it is taken to mk to be stripped to the last bolt, for there must be an answer, one that MB might need to know for other customers as well