excessive use of egr
08-21-2018, 03:00 PM
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r320 cdi 4 motion long
excessive use of egr
Hi.
I have a Mercedes r320 cdi from 2006. Problem with the car is with the egr controls.. First. Engine was hard to start, at the first start every day, second. The exhaust tips where filled with black soot. Third. The engine was very labored at low load, it sounded like it was knocking and didn't burn the fuel correctly. Fourth. When the engine sounded labored the car would miss and stumble. I removed the ego valve for cleaning, it was not bad at all. I inspected ego cooler and every egr related component, all checked out fine. After installing the egr valve back on car, I unplugged the egr valve, installed a 2.7 K ohm withstand to cheat the ECU, to believe the egr valve still was attached. Then I drove the car for several hundred of kilometers. Car drove fine, sounded good and did not jerk, stumble or anything else. I installed a brand new egr valve, but the stumble and jerking is back. Checked with my icarsoft Mb ii and found the ego valve to give too much egr flow, too the point where the engine cannot burn the fuel from the lack og oxygen. could it be the exhaust back pressure sensor, the oxygen sensor before catalyst or the manifold pressure sensor that's responsible for opening the egr valve too much.
Hope you can enlighten me..... kind regards stig
I have a Mercedes r320 cdi from 2006. Problem with the car is with the egr controls.. First. Engine was hard to start, at the first start every day, second. The exhaust tips where filled with black soot. Third. The engine was very labored at low load, it sounded like it was knocking and didn't burn the fuel correctly. Fourth. When the engine sounded labored the car would miss and stumble. I removed the ego valve for cleaning, it was not bad at all. I inspected ego cooler and every egr related component, all checked out fine. After installing the egr valve back on car, I unplugged the egr valve, installed a 2.7 K ohm withstand to cheat the ECU, to believe the egr valve still was attached. Then I drove the car for several hundred of kilometers. Car drove fine, sounded good and did not jerk, stumble or anything else. I installed a brand new egr valve, but the stumble and jerking is back. Checked with my icarsoft Mb ii and found the ego valve to give too much egr flow, too the point where the engine cannot burn the fuel from the lack og oxygen. could it be the exhaust back pressure sensor, the oxygen sensor before catalyst or the manifold pressure sensor that's responsible for opening the egr valve too much.
Hope you can enlighten me..... kind regards stig
Last edited by stig70; 08-21-2018 at 03:14 PM. Reason: spelling
08-22-2018, 03:41 PM
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r320 cdi 4 motion long
Thanks for your response.
The local Mercedes dealership have performed an injector leakdown test, they also tested the fuel pressure in the fuel delivery system, from lift pump to high pressure pump, rail pressure etc. I don't know the exact results, but the chief mechanic at the Mercedes dealer told me all was fine and the problem wasn't within the injectors or fuel pressure.
Better safe than sorry ( was on my mind ) so I went a head and changed the high pressure pump and the fuel quantity ( volume ) valve, just for the sake of it.... same problem with the car... engine misses at very light throttle input.
Today I went a head and pulled the wire plug off of the boost pressure sensor, while I observed the egr valve actuation percentage... It went to zero. No more egr
Valve actuation.
After the plug was reattached and the fault code cleared, the egr Valve kicked into action again. I switched to observe the boost pressure signal while I pushed the pedal towards the metal. I think it was kind of slow reacting to the changes. And wasn't reading very much..... could get it up to approx. 1215 mbar under heavy throttle in neutral gear. I've installed a new boost sensor, it seems to react much quicker and I can get it to approx. 1450-1600 when revving the engine in neutral. Under heavy acceleration it goes to 2400 mbar. Approx. 34.80 psi.
I did drive around the block after the new boost sensor was installed, and didn't notice the problem.. but my hopes are low.
Kind regards Stig
The local Mercedes dealership have performed an injector leakdown test, they also tested the fuel pressure in the fuel delivery system, from lift pump to high pressure pump, rail pressure etc. I don't know the exact results, but the chief mechanic at the Mercedes dealer told me all was fine and the problem wasn't within the injectors or fuel pressure.
Better safe than sorry ( was on my mind ) so I went a head and changed the high pressure pump and the fuel quantity ( volume ) valve, just for the sake of it.... same problem with the car... engine misses at very light throttle input.
Today I went a head and pulled the wire plug off of the boost pressure sensor, while I observed the egr valve actuation percentage... It went to zero. No more egr
Valve actuation.
After the plug was reattached and the fault code cleared, the egr Valve kicked into action again. I switched to observe the boost pressure signal while I pushed the pedal towards the metal. I think it was kind of slow reacting to the changes. And wasn't reading very much..... could get it up to approx. 1215 mbar under heavy throttle in neutral gear. I've installed a new boost sensor, it seems to react much quicker and I can get it to approx. 1450-1600 when revving the engine in neutral. Under heavy acceleration it goes to 2400 mbar. Approx. 34.80 psi.
I did drive around the block after the new boost sensor was installed, and didn't notice the problem.. but my hopes are low.
Kind regards Stig
