I suspect low grade gas in the high test tanks.
I always run premium.
I just happened to put a few gallons of 89 octane in the car one day to see if the car would run ok on it, and it did not run as nice, so I put premium back in, and all was good. then I drove for a bit, used that tank, and I put in a new tank of premium, and the problem appeared again, which leads me to believe that gas is the culprit.
so I am thinking they either downmixed the 92 with 87, or they put 87 in the 92 tanks to rip us off. I've seen it on several news reports that stations are doing it here in los angeles.
I'm going to run some cleaner through it, techron probably, and change the fuel filter and see how it goes.
I'm going to check for a fouled plug too it could be something stupid.
The engine idles smooth, and the car's gas mileage has not decreased, so Thats why it seems strange. Like its not getting enough spark on startup only.
The rich mixture is because when I turn it over, it turns over more, then catches, then dies, then I turn it over again and it catches and holds. Its like its not getting enough fuel or the wrong grade. Because it showed a similar hard starting symptom with 89 octane, but not with premium, but it could be 87. I'll run some cleaner through. I have no idea how water could have gotten in there between fill ups, its been nice and sunny out.
Even after a spirited run of 80 + MPH on the freeway the car still shows the symptoms, and feels like its a little less powerful, which is why I think it might be bad gas?
Is that a possibility?
I don't mind changing some ignition/fuel components, but I'd rather try the cleaning approach first and see if thats the issue.
And I'd also like to try another station and see.
Or should I get the gas tested to see if its low grade, in which case, the gas station will need to be dealt with....
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.