The OVP has no influence in spark quality. Measure the resistance of that plug wire as it should have the correct resistance stamped on it.

If that proves successful then check rotor + cap for damage or arching.

A 190 2.6 does not have a MAS. It uses an airflow potentiometer which is a very simplistic version which only influence is fuel enchrichment adaptation on acceleration. There is, however, a cold air sensor at the front of the intake. I would start with the spark issue though.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

I did the repair on the upper timing cover about 3 weeks ago to fix the leakage. At that time I replaced the rotor, distributor cap, & wiring. I, also, put in the oe spec. plugs. I thought I had the issue solved till the other day on the cold snap & it failed to start again. I am in the process of getting a new over voltage relay on the way. I am not 100 percent positive it is the weak link, but I am optimistic it is the problem. The reason being the immediate change of no start to starting right up the instant I jostled it around & removed the fuse etc. I am not sure why they changed to the 2T on the relay? Like maybe the original has some issues or something?? Anyway, if it fixes the problem by replacing the relay, it will definitely be a cause to celebrate!

http://catalog.peachparts.com/ShopByVehicle.epc?q=1991-Mercedes--Benz-190e--.6-Body--Electrical&yearid=1991%40%401991&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6130%3AED%7C10000011%3ASM%7C847%3AMBC%7C1486%40%40190E+2%2E6&catid=241959%40%40Body+Electrical&subcatid=242017@@MAS+Control+Unit&mode=PD

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"