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Marty, I wanted to give you an update on our experiment with…

Hi Marty,I wanted to give...
Hi Marty,I wanted to give you an update on our experiment with the R16 Resistor on my 300E and then ask you a new question.The R16 resistor swap worked. I ended up installing the one that is 2 degrees retarded compared to the standard one. It seems to have eliminated the pinging problem. But, here is an interesting tidbit. There is actually no difference in timing measured by a timing light at idle or at higher RPM's with the vacuum line connected. You only see the difference with the vacuum line disconnected specially at higher RPM's. I think the R16 change doesn't just retard the ignition like older cars with an adjustable distributor. Rather, it puts the EZL on a different MAP. The resistor that was in the car was part no.(###) ###-####and the one I installed is(###) ###-#### I also had to get the car smogged (done on a dyno in California) last week. My 15 mile per hour NOX number stayed the same before and after the swap both on the high side, but within limits), but the NOX number at 25 miles per hour dropped substantially. So, it seems like you see the difference in timing only when the engine is under load.Now, my next question: My oil pressure at idle has suddenly dropped a lot. I first noticed it shortly after the resistor swap, although I don't think they are related. The pressure used to be at about 1.5 bars at idle and jump to 3 bars with a little gas, even after a long, fast drive on a hot day. It had always behave like that as far back as I can remember. Now, the weather has been in the mid-50's here and after about 15-20 minutes of driving at about 60-70 miles/hour it drops down to 1 bar and if you get the engine hot enough it even drops below 1 bar. I know Mercedes says it can drop down to .3 bar without causing problems, but the fact that the change happened from one day to the next, is a bit strange. Any ideas? If you'd like we can do a phone call. I don't know how to initiate it from my end, but I think you can. I look forward to it.Regards,
Massoud
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Answered in 11 minutes by:
1/19/2018
Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 54,750
Experience: Bosch Certified Master Tech. Over 35 years experience.
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Hi Massoud, thanks for the very enlightening update! I'm glad it worked out.

In regards ***** ***** oil pressure, I would first perform an oil pressure test using a mechanical gauge. Most of the problems that I see are with the pressure sensor itself. If the oil and filter have not been replaced recently I would recommend doing that as well. I would only be concerned if the pressure was below 10 psi at idle when hot. And yes, Mercedes does say the pressure can go as low as 0.3 bar but if it runs that low I would say you have internal bearing wear or a weak oil pump. 1 bar at idle is still pretty darn good. I'm inclined to think that you have a pressure sensor problem as opposed to an actual oil pressure problem.

Marty
Marty, Mercedes Technician
Category: Mercedes
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Customer reply replied 11 days ago
Hi Marty,
Just wanted to update you on our recent conversation about the recent oil pressure discussion we had about my 300E. I had the oil pressure sending unit replaced with a new genuine unit. The problem went away. It looked like the old unit was leaking internally as well as to the outside. The pressure sits at about 1.5 bars at idle after a hard run. Thanks again for everything.
Massoud
Fantastic! I’m glad everything worked out.
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