High NOx
Thread Starter
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Junior Member
Joined: Nov 2008
Posts: 17
From: Waterloo, Ontario
High NOx
On my 1990 300E, I replaced new EGR valve (old one was leaking),
EGRsolenoid tested on bench with 12V and works good.Vaccum is present at the inlet tube. But the EGR valve will not open when engine is warm and reved uo to 2500rpm.. If I apply vaccum bypassing the solenoid, EGR valve opens.
Means there is no power coming to the solenoid when engine warm and reved at 2000-3000 rpm. Is there any component that energises the EGR solenoid in that condition, enginewarm and reved to 2000-3000rpm? Or am I missing something....?
Thanks
EGRsolenoid tested on bench with 12V and works good.Vaccum is present at the inlet tube. But the EGR valve will not open when engine is warm and reved uo to 2500rpm.. If I apply vaccum bypassing the solenoid, EGR valve opens.
Means there is no power coming to the solenoid when engine warm and reved at 2000-3000 rpm. Is there any component that energises the EGR solenoid in that condition, enginewarm and reved to 2000-3000rpm? Or am I missing something....?
Thanks
Senior Member
Joined: Dec 2004
Posts: 2,410
From:
RE: High NOx
Hi,
The EGR only works under certain conditions. I cannot advise exactly what they are but in general terms when combustion temperatures are high.
You state that the valve works OK on the bench.
Are you sure that vacuum is present (to operate the valve) when installed in the vehicle. If so how did you confirm that this is the case? Maybe you assumed that vac would be present.
If you are looking to reduce NOx levels to get thru the test then purely as a suggestion what happens if you operate the valve with an independent 12v supply. Most likely it will cause issues with rough idle, lack of power etc and may not give you what you are looking for.
Is this your first post on this subject or did I reply earlier stating that the cats play a part in reducing NOx as well as the EGR?
Stuart
The EGR only works under certain conditions. I cannot advise exactly what they are but in general terms when combustion temperatures are high.
You state that the valve works OK on the bench.
Are you sure that vacuum is present (to operate the valve) when installed in the vehicle. If so how did you confirm that this is the case? Maybe you assumed that vac would be present.
If you are looking to reduce NOx levels to get thru the test then purely as a suggestion what happens if you operate the valve with an independent 12v supply. Most likely it will cause issues with rough idle, lack of power etc and may not give you what you are looking for.
Is this your first post on this subject or did I reply earlier stating that the cats play a part in reducing NOx as well as the EGR?
Stuart
Thread Starter
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Junior Member
Joined: Nov 2008
Posts: 17
From: Waterloo, Ontario
RE: High NOx
Thanks for the reply.
Yes, I supplied 12 volts independently to the valve solenoid and opens the valve causeing to run rough idle, lack of power, etc. There is vaccum going to the solenoid but does not get energised when engine is hot and reved at 2000-3000 rpm.. I also put vaccum to the EGR valve with a vaccum pump at idle and it opens causing rough idle. Just that the solenoid does not get power in that condition to open the EGR valve. Solenoid and EGR valve are fine but no power goes to the solenoid.
Yes, I supplied 12 volts independently to the valve solenoid and opens the valve causeing to run rough idle, lack of power, etc. There is vaccum going to the solenoid but does not get energised when engine is hot and reved at 2000-3000 rpm.. I also put vaccum to the EGR valve with a vaccum pump at idle and it opens causing rough idle. Just that the solenoid does not get power in that condition to open the EGR valve. Solenoid and EGR valve are fine but no power goes to the solenoid.
Senior Member
Joined: Dec 2004
Posts: 2,410
From:
RE: High NOx
Switching of the EGR valve is done by the engine ECU. Without actually looking at the installation and my WIS is not up and running at present, I'm not sure whether the ECU output is via a relay / fuse etc. If not and assuming no output signal exists then it looks as though the ECU is at fault.
Mmm. Running out of suggestions to help.
Stuart.
Mmm. Running out of suggestions to help.
Stuart.
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