1995 E420 poor performance with 92 octane - PeachParts Mercedes-Benz Forum

DuckMuck · #1 08-20-2003, 12:56 PM

Gas here in Vancouver, BC peaked at 88.6 cents Canadian/liter yesterday, and has been hovering in the mid-80's for some time...my low-fuel light came on a while ago, and this morning, I went to the station to get filled up...since the car was new, I have been using 94 octane consistently...but since gas prices were so high, I gave 92 octane a try...I didn't think it was a big deal, since the manual said anything about 91 octane was good enough...

Oddly enough, the car idled rough...and had odd hiccups ever so often (I am guessing this is knocking)...and when I put my feet down on the accelerator...it was not silky like before, but was harsh...and the engine lacked power...is some sensor off in the car, or do I have to wait a while for the car to adjust to the new grade of gas? I didn't see any lights come on...I was under the assumption that many states in the US only have 92 octane as max, and many of you guys are running in E420's with 92 octane...and I have not heard any complaints around here concerning odd behaviour...and you guys are using it daily...I am guessin' emissions is the same between Canada and US cars...I find it a little odd...the car was in for a major service at the dealership a little under 5000km ago and the odometer has a little under 49,000km right now...all fluids were changed and the car has been running well lately with no problems at all...thanx for any insight...

y2kimmel · #2 08-20-2003, 01:34 PM

I don't think that 92 octane should cause any of your problems. i use it regularly with my 1995 E420 and it runs great.

Some possible causes:

1) You ran your tank too low, and the fuel pump picked up crud that is clogging your fuel filter. Have you had the fuel filter changed on the car?

2) Perhaps your car needs rotors and caps early - and coincidentally decided to start acting funny now.

3) Engine Wiring harness?

These are listed in order of likelihood. By the way - the car should never knock - as it has knock sensors that will retard the timing to account for any gas quality. You could run 87 octane in the car with no knocking - the car would just adjust timing - and you'd get poor performance.

Troy
1995 E420 (living through an evaporator repair)

wjm · #3 08-20-2003, 06:09 PM

I agree with Troy. Here in metro detroit, there are few stations that carry 94 octane. Mose high octane gas here is 92.. unless you go to Shell and maybe others. I have never had a problem with 92.