Yes guys, my mom has been putting unleaded 87 Octane in her 2004 C-Class compressor for the past 8 months. For the past week shes says that when shes stops shes hears knocking in the engine, also it feels as if the car is going to die at times. She took the car to the mechanic. They have had it for 2 days hooked up to the computer and apparently there is nothing wrong with the car according to the computer. Im starting to think it has to do with the gas she has been putting in???


Any ideas??

Fuel Injectors dirty?

 

OMG NOT GOOD SORRY TO HEAR ABOUT THAT.

 

Lower octane gas in an engine that is designed for higher can ping which is an explosion rather than a controlled burn, it puts significant pressure on valves, pistons and so on. If the car seems fine just start using the higher octane gas and see if the noises vanish. If an engine is designed for higher octane gas, using lower octane can damage it. The inverse is not true, just a waste of money!

Lawrence

 

Yea, i remember back when I was 16 i worked for a Construction company and my boss told me to go get gas in his Chevy truck. I went and filled it up and then later that day he returned from where ever and he asked me what kind of gas i put in it. I said, regular un;eaded, he said you can't run low grade fuel in a HIgh performance engine. Apparently the motor was built and was knocking and pinging like crazy.
Definately have to run AT LEAST mid grade in a Forced induction engine. I have been running 89 octane in my Volvo C70 Turbo for a year and never had a issue but wouldn't try any lower than mid grade. I know I am pushing it by running mid grade as it is. But I don't hear any knocking at all and my performance is still the same. Best thing is to run premium for the mercedes, especially a kompressor

 

Thanks alot guys, great feedback. Im going to tell her to start using high octane.