Two excellent replies I did not think about! From experience, I know low engine vacuum is related to timing and I should have thought of that considering that exhaust sound at startups! I will remove the valve cover and check the alignment marks on the cam and crank. I will also use my timing light. I beleieve I have the specs.
About the EGR, I don't know how it could effect the low vacuum condition I have or drivebility! All I know is that it lowers NOx emissions buy redirecting some of exhaust gases back into the cylinders. The idea here is: If you lower the cylinder gases temperature, you will lower your NOx. The exhaust redirected by the EGR has H2O as a product of the combustion process and that what lowers the temperature in the cylinders. Anyways, How can I test it?
I will do some tests by this weekend and post results.
Thank you guys,
More suggestions are welcome..
1993 190E 2.6
Advanced Diesel Systems Test and Research Engineer