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CC2005
I have spent a lot of time looking over lots of forums and trying to work out ways to disable the egr system or trick the ecu into thinking that everything is fine.
Most EGR systems are monitored by the Maf sensor.
When the EGR valve opens and the throttle butterfly in the intake partially closes, there is a drop in the air flow through the sensor.
The ECU has an expected range that the the maf flow should drop.
With an egr blanking plate, there is almost no drop in maf flow because there is no exhaust gas entering the intake manifold, so all of the air into the engine is still coming through the MAF sensor.
A circuit can be made up that wires into the MAF flow sensor and the egr position sensor that will lower the maf flow voltage when the egr position sensor shows that the egr is open.
Some cars use a Map sensor to monitor the egr.
When the egr valve open and the intake butterfly partially closes there is a slight drop in manifold pressure.
That is if the Map sensor is positioned between the throttle butterfly and the engine.
With the EGR blanked off there is a no exhaust gas flowing into the intake manifold, so there is a larger drop in manifold pressure because the engine is trying to suck air past a partially closed throttle butterfly.
An answer for engines that use the Map sensor to monitor the egr is to drill a hole in the throttle butterfly.
That will allow enough air past the partially closed intake butterfly so the manifold pressure doesn't drop low enough for the ecu to see a problem.
The Problem with drilling a hole in the throttle butterfly is that is also used to completely close and choke the engine on shutdown.
This causes a smother shutdown but more importantly it will stop any engine run on, as rare as that may be.
The simple answer for most modern diesels is to stop the ecu activating the egr system at all.
This is done by finding the Intake Air Temp sensor wire in the MAF and cutting it and adding a resistor in line to lower the voltage the ecu sees.
The lower voltage makes the ecu think that the intake air temp is lower and below the point where it will activate the EGR system.
I would still Blank the egr off to be certain that there is no chance of exhaust entering the intake, but because the ecu does not activate the egr system there is no egr fault codes.
On my old Holden Rodeo with, an Isuzu commonrail engine in it, the temp the egr activated was at about 5 degrees C.
A 4K resistor was enough to make the ecu think it was a maximum of 2 degrees all the time.
An easier way to do it is to wire in a potentiometer and then adjust it until it has enough resistance to lower the intake temp voltage until the egr system is disabled.
This is easy to do if you have the Torque app on your phone and a Bluetooth obd reader.
You can monitor the commanded egr percentage and watch it drop to zero.
This has NO effect on engine tune because there is usually another intake air temp sensor in the MAP sensor.
This sensor is after the intercooler and is therefore the temp that the ecu uses for its fuel calcs.
EDIT:
After typing all of the above I realised that it looks like CC2005 already knows about the easy way to go about it and was just try to work out another way to do it just to keep his mind occupied.
Im glad its Friday because I clearly need a rest and maybe a beer or two.
I have spent a lot of time looking over lots of forums and trying to work out ways to disable the egr system or trick the ecu into thinking that everything is fine.
Most EGR systems are monitored by the Maf sensor.
When the EGR valve opens and the throttle butterfly in the intake partially closes, there is a drop in the air flow through the sensor.
The ECU has an expected range that the the maf flow should drop.
With an egr blanking plate, there is almost no drop in maf flow because there is no exhaust gas entering the intake manifold, so all of the air into the engine is still coming through the MAF sensor.
A circuit can be made up that wires into the MAF flow sensor and the egr position sensor that will lower the maf flow voltage when the egr position sensor shows that the egr is open.
Some cars use a Map sensor to monitor the egr.
When the egr valve open and the intake butterfly partially closes there is a slight drop in manifold pressure.
That is if the Map sensor is positioned between the throttle butterfly and the engine.
With the EGR blanked off there is a no exhaust gas flowing into the intake manifold, so there is a larger drop in manifold pressure because the engine is trying to suck air past a partially closed throttle butterfly.
An answer for engines that use the Map sensor to monitor the egr is to drill a hole in the throttle butterfly.
That will allow enough air past the partially closed intake butterfly so the manifold pressure doesn't drop low enough for the ecu to see a problem.
The Problem with drilling a hole in the throttle butterfly is that is also used to completely close and choke the engine on shutdown.
This causes a smother shutdown but more importantly it will stop any engine run on, as rare as that may be.
The simple answer for most modern diesels is to stop the ecu activating the egr system at all.
This is done by finding the Intake Air Temp sensor wire in the MAF and cutting it and adding a resistor in line to lower the voltage the ecu sees.
The lower voltage makes the ecu think that the intake air temp is lower and below the point where it will activate the EGR system.
I would still Blank the egr off to be certain that there is no chance of exhaust entering the intake, but because the ecu does not activate the egr system there is no egr fault codes.
On my old Holden Rodeo with, an Isuzu commonrail engine in it, the temp the egr activated was at about 5 degrees C.
A 4K resistor was enough to make the ecu think it was a maximum of 2 degrees all the time.
An easier way to do it is to wire in a potentiometer and then adjust it until it has enough resistance to lower the intake temp voltage until the egr system is disabled.
This is easy to do if you have the Torque app on your phone and a Bluetooth obd reader.
You can monitor the commanded egr percentage and watch it drop to zero.
This has NO effect on engine tune because there is usually another intake air temp sensor in the MAP sensor.
This sensor is after the intercooler and is therefore the temp that the ecu uses for its fuel calcs.
EDIT:
After typing all of the above I realised that it looks like CC2005 already knows about the easy way to go about it and was just try to work out another way to do it just to keep his mind occupied.
Im glad its Friday because I clearly need a rest and maybe a beer or two.
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