EGR defeat for WG 2.7 CRD

[piper]

Dis-connecting the EGR will also possibly give the motor a rougher idle especially on cold
For the plug pins, if you could find some household 240v power cable single strand copper, strip the plastic off, maybe tight in the plug socket, so just roll it between 2 x pieces of steel till thinner then solder your wires on the end and it should stay there

[fester]

Yeah something like that would work ok as long as you are sure it's secure. Those solid wires could be bent over 180 degrees and put into the plug so they face back down the plug instead away from, then they could taped or heat shrinked to the body of the plug and the wiring run back down the original wiring.

Not sure about the idle, I would guess the opposite as I thought the exhaust gas would affect idle. When closed nothing would happen. I'm only going by the merc guys and they seen to suggest no ill effects. There was some talk that cold starting and warm up would be affected buy couple of the English guys have reported nothing to speak of so I would assume the impact to us would be negligible. Many of the 3.0 l guys have done the manifold clean and shunt and said idle quality improved greatly. Maybe the 3.0 l is more susceptible to tough running. Be interesting to see the reports here.

[SMBCJ]

Mine still idles quite smoothly but from what I gather the EGR is closed after 60 sec of idling (and at wide open throttle). It's mostly in use at part throttle (to varying degrees) according to the ECU control parameters (speed, throttle opening, engine temp, engine load, etc.).

I don't know whether it's my imagination, but it seems to have a bit more throttle response now, after the mod.

[fester]

Supposedly improves economy too but we'll see about that one. I plugged the line as well just in case. I did get carried away when the manifold was off and welded the outlet up to be 100% sure. The mercs appear to have a different type of EGR valve as some have to pull theirs out first and clean to make sure they shut properly, there is a bit of talk about locking the spring or adding tension. So maybe if you still have problems you could pull the valve out and put a spacer under the spring. I can't see ours would need it though as the spring seems pretty strong and it's hard to imagine exhaust pressure overpowering it.

[bodgie]

I've done the mod and so far I'm happy with the results. It did take a while for the ECU to learn about the changes but it seems to be getting better every day of driving.

I'm going to play with increasing the value of the 470ohm resistor, am going to add a little resistance as I think this value may be a little low. To me the engine at idle seems to "hunt" a little bit.

The one thing that amazes me is how the visible emissions out the exhaust have almost disappeared, much happier. Also I can't say warm-up time isn't any slower and as for economy it's to early to tell.

Jason

[piper]

Originally Posted by bodgie

I've done the mod and so far I'm happy with the results. It did take a while for the ECU to learn about the changes but it seems to be getting better every day of driving.

I'm going to play with increasing the value of the 470ohm resistor, am going to add a little resistance as I think this value may be a little low. To me the engine at idle seems to "hunt" a little bit.

The one thing that amazes me is how the visible emissions out the exhaust have almost disappeared, much happier. Also I can't say warm-up time isn't any slower and as for economy it's to early to tell.

Jason

the mod should work perfect nothing for the ecu to learn and the resistor 470ohm should be spot on

[fester]

Piper is right. The shunt is to trick the ECU into thinking nothing has changed therefore it should not have to learn anything so I'm not sure what it means in your case. The merc boys tested with voltage and oscilloscope to come up with that resistor. It was commented that the value was not super critical but 470 ohm was a good match to change the voltage. So other values may work but not sure if they will make any difference. If you think it can improve you could try testing the voltage change when the EGR is connected and working to come up with a different resistor value if needed. Even though we have a different ECU I suspect the signal voltages will be the same as we use the same EGR actuator and most importantly the same MAF.

Interesting to see your results and if anyone else is showing differing results. Not that it is overly critical given the timing when the EGR normally functions.