I've been reading threads on EGR valve issues, blanking and restrictors. While I have an '06 Croma, this is applicable to all 1.9 16V JTD engines. I don't like the idea of complete blanking as it increases emissions, is technically illegal in the UK and needs an ECU update on 16V engines to prevent a failure being detected. So I've got the official restrictor plate, the later 55225287 type with integral gaskets. This is a thin plate with 4 holes each about 7mm diameter. While this obviously reduces the open area of the outlet port, what does it do to the flow? According to eLearn the EGR valve solenoid is driven by a square wave "modulation" signal. Allowing for translation, this indicates a pulse width modulation (PWM) scheme that controls the average current through solenoid and thus the amount the EGR valve opens. The management system adjusts the pulse width to control the valve in a closed loop system. The mass airflow sensor provides feedback. If this is correct, putting a restrictor plate will not change the amount of gas recirculated, except for the EGR valve fully open case. If you just wanted to reduce the flow it could be done with an ECU update, no "spannering" required. I can see three possible effects of adding the plate.
1/ The EGR Valve will have to open further to get the required flow. This will probably reduce build-up and clogging in the valve as the opening will be bigger and the parts will move over a longer distance with more force applied.
2/ There will be more back pressure in the EGR valve. I can't see any advantage here but have not looked closely at the valve design.
3/ The exhaust gas will enter the inlet manifold in 4 high(er) velocity jets rather than a slow bulk flow. This may help mixing of exhaust and inlet flow due to turbulance etc.
Anyone else have any ideas on what is going on?
Out of interest I'm going to monitor the EGR valve signal before and after fitting the restrictor plate to see if it opens more with the restrictor installed.
1/ The EGR Valve will have to open further to get the required flow. This will probably reduce build-up and clogging in the valve as the opening will be bigger and the parts will move over a longer distance with more force applied.
2/ There will be more back pressure in the EGR valve. I can't see any advantage here but have not looked closely at the valve design.
3/ The exhaust gas will enter the inlet manifold in 4 high(er) velocity jets rather than a slow bulk flow. This may help mixing of exhaust and inlet flow due to turbulance etc.
Anyone else have any ideas on what is going on?
Out of interest I'm going to monitor the EGR valve signal before and after fitting the restrictor plate to see if it opens more with the restrictor installed.