"Flat spots" in acceleration curve - PeachParts Mercedes-Benz Forum

pawoSD · #1 07-01-2009, 01:01 AM

I'll add some new info....I went cheapo and tried midgrade in my 300E, and well well well, it runs perfectly fine/the same on it. I got 22mpg going 74mph for 250 miles with the A/C on full blast and the car full of camping equipment last week. I won't use regular, but since Midgrade works, that's what I'll be using....engine runs/sounds/feels/performs exactly the same as on premium....in fact, I think it idles a bit better and starts a little easier. I still use the redline in it to keep it clean though.

mbzman · #2 07-01-2009, 01:36 AM

I had a similar problem with my M103 in my 300CE. It would hesitate at times, especially when cold. I too could feel a noticeable flat spot in the acceleration curve. I had recently done the head gasket and top end. All six injectors and seals were replaced as well as the fuel accumulator. Turns out that it was a defective fuel pressure regulator. The hesitation is gone and it starts without any problems now. By the way, I too have used mid and high grade fuels and have found that there is almost no difference in engine performance between the two.

Cal Learner · #3 07-01-2009, 07:52 AM

Thanks for the comments. The fuel pressure reg is original, so I'll put that on the to-do list. I think the first step will be pressure testing to see what's what in that area.

JamesDean · #4 07-01-2009, 12:23 PM

Quote:

Originally Posted by pawoSD

I'll add some new info....I went cheapo and tried midgrade in my 300E, and well well well, it runs perfectly fine/the same on it. I got 22mpg going 74mph for 250 miles with the A/C on full blast and the car full of camping equipment last week. I won't use regular, but since Midgrade works, that's what I'll be using....engine runs/sounds/feels/performs exactly the same as on premium....in fact, I think it idles a bit better and starts a little easier. I still use the redline in it to keep it clean though.

You got 22 with the ac on? Hmm. I must be doing something wrong. I have a m103 3L in my 190E and I got 17mpg with the ac on. I usually get around 21 with out a/c... I would love to get 22 with a/c on...