Engine: D52447: Help with "Engine System Service"

[Clan]

Originally Posted by Coldrow

Had a similar thought myself about something else causing the low figure and It's something Clan said about the EGR that got me thinking (EGR open lowers the MAF readings).

The sudden jump from 27 to 45Kg/hr could be something like the EGR valve closing...? When i graphed the MAF it does literally jump in a split second and the readings are steady either side of the jump in the figures.

So, what else besides a faulty EGR valve could lower the intake MAF readings like this?

I did say above:
"Air mass readout is about 53 kg/hr idling warm , it will lower when egr valve opens so ignore that .

[Coldrow]

Originally Posted by Clan

I did say above:
"Air mass readout is about 53 kg/hr idling warm , it will lower when egr valve opens so ignore that .

Clan, yes I did understand that but what I was trying to say in an earlier post is that it takes about 2-3 minutes idling to actually readout anything like 53Kg/hr (mine was reading 45-47). Before that it actually reads about 27.

So my question is this, should the MAF Kg/hr reading settle immediately to 57kg/hr as the car hits idle? or does it take 2-3 minutes continuous idle like it does on my car?

I will be doing some measurments at various RPM later to see if they compare at all to cheshired5's readings.

[Clan]

Originally Posted by Coldrow

Clan, yes I did understand that but what I was trying to say in an earlier post is that it takes about 2-3 minutes idling to actually readout anything like 53Kg/hr (mine was reading 45-47). Before that it actually reads about 27.

So my question is this, should the MAF Kg/hr reading settle immediately to 57kg/hr as the car hits idle? or does it take 2-3 minutes continuous idle like it does on my car?

I will be doing some measurments at various RPM later to see if they compare at all to cheshired5's readings.

it depends when the EGR valve opens , as to when the reading drops to 27 ... i havent studied the EGR opening periods myself ... but ignore the lower readings, it is only the upper reading with EGR closed that is documented ...

[Coldrow]

Ok, finally had time to re-run the tests.

I mapped the EGR position and it takes 2-3 minutes for it to fully close after resting on idle and when it closes the MAF readings increase. It remains open 20% after the throttle has been pressed and does not instantly close when you lift off, whether this is what should happen I have no idea.??

MAF Readings as follows

Tick-over - 50 Kg/hr
1000 RPM - 40 Kg/hr
2000 RPM - 80 Kg/hr
3000 RPM - 260 Kg/hr

That last reading seems out of sync... but,

Cheshired5's readings translated to Kg/hr for a Euro 3 D5

Tick-over - 46.8 Kg/hr
1000 RPM - 72 Kg/hr
2000 RPM - 169.2 Kg/hr
3000 RPM - 244.8 Kg/hr

Has someone with a Euro4 D5 mapped the MAF readings? I'm thinking the EGR system on the Euro4 D5 means you can't compare to the Euro3 D5.

Thanks

Edit, As I'm no nearer to bottoming this I've continued researching the Net and a T5D5 member had a similar issue throwing up errors for the MAF, boost and swirl. His problem was finally traced to one of the vacuum engine mounts.

[outnumbered]

I had Ecm 135f 2 months ago traced it down to the two clips at the rocker cover where pipe fits from the Egr valve sensor, seing as there has been work done in that area its worth a look.
mike

[Coldrow]

A little update to this problem.

"Engine System Service Required" has become more regular and in differing circumstances but the only faults logged are for the EGR valvle position censor.

As a result I have monitored the "EGR Desired" and "EGR Position Censor" values in the vehicle communication section of VIDA. These values in percentage should (i think) add up to 100%. I have noticed that sometimes after a blip of the throttle the EGR pos censor will "stall" on it's readout as in reading 60% when the EGR desired is 80% (actual reading of the position censor should be 20% for 80% desired).

When the above happens I get the system service message in the car information display.

I have also noticed on tick-over when the valve should be fully closed (as desired by ECM) that it actually reports it as 1% open. Maybe that is an acceptable disparity or maybe it should be 0%??

I had no codes registered for the MAF but I suspect these will appear if you drive for any distance in limp mode.

I have tried cleaning the block connector as a starting point but this has not fixed it. So it is either faulty wiring or the EGR position censor (more likely i suspect) is on it's way out.

Can the censor be repaired/cleaned? has anyone else had this problem before?

[Coldrow]

Just thought I'd update my thread.

Bought a genuine new Bosch MAF today and I'm now getting +10/12 more Kg/Hr metering through the MAF. It now idles at 52-53 Kg/hr which according to chesired5/clan is about right.

Time will tell if it's done the trick but if I get limp mode back I'll update again.

So in the end I've done a full EGR clean, a service which was due, changed the MAF and for good measure I did a DPF regen.

Thanks for the suggestions all.