My 1990 300E failed emission on NoX and engine temperature does not go more than 80-85. Can some one help if it the ignition timing or EGR or EGR pipe blockage. Also how to adjust timing.

 

Have you replaced the thermostat?retard the timing a few degrees.Make sure the engine is up to operating temp before the test,even if you need to put a piece of cardboard in front of the radiator and pull it out before you go to the test station.
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Thanks olord. I will try that. As well I am going to get the EGR and the EGR pipe cleaned by a mechanic just to be safe. I had valve seal problems as it was burning oil and had the seals replaced by Mercedes dealer in Kitchener, Ontario for $840.00. I have heard that if the EGR pipe is blocked by oil residue, the engine may run colder. After the valve job, when I accelerate, the tappets are slightly noisy. Does this mean that the timing has changed?
Thanks.

 

He should have set the valves.New seals would not have lifters tapping.

 

How can you adjust the timing on a 1990 300E?