EGR crossover switch and engine miss
Folks on the benzworld g forum said perhaps someone over here could help on this. I have a 1996 G-320, LWB 463 with a M 104 engine with 156,000.
I have had an intermittent miss/power loss for some time now that motivated me to buy a retriever to pull fault codes. There is a fault (92 – ECR switchover valve Y27 open/short) which was not a faulty valve (replaced it, and old seem fine with one ohmmeter). This is located in the front of the engine under the plastic cover. The wire also seemed OK – good ground and other lead with high resistance. There is a second connector tie wrapped to one of the vacuum hoses which apparently goes to an air pump not fitted to this engine. This unused connector has a straight connector and longer wire then the right angle and shorter cable connected to Y27. If I connect the unused straight connector to the valve, the fault goes away. It seems rather obvious that at some point in the past this was connected wrong, but the shorter cable with the right angle connector is a much better fit. Can someone verify this on a similar engine?
It seems that if it was switched, it would have happened about 60,000 miles and 3 years ago when the head was pulled. It does not seem to me this would be causing my current miss.
The miss I have started about 7,000 miles ago as a significant loss of power – probable more then 1 cylinder – for about 10 seconds every 300 miles or so. It seemed that perhaps a coil was at fault and I replaced all three of them – no change. It has gradually gotten much worse, in that when it happens it lasts for minutes. It seems to never occur until after the engine has run 75-150 miles but does not seem to be related to temperature, and I recently discovered that it will go away as soon as the ignition is turned off and engine restarted. The fault it brings up is 55 – Ignition out stage or coil T1 misfiring and shuts down 2 cylinders associated with that coil.
Any help on this problem would be greatly appreciated.